Samarthya.Me: My technical journey. on Samarthya

Learning OSV, part 5: I scanned my own blog, and the real problem wasn't in the report

Wed, 04 Nov 2026 21:00:00 -0500

A test project is a controlled experiment; your own repository is the one that talks back. I pointed OSV-Scanner at the source of this blog expecting a dull report. The report was indeed dull. The interesting part was what it could not see.

The mood of the evening. It lasted until the first command.

In parts 2 and 3 I used a project built to be vulnerable. This time the target is the repository behind this site: Hugo, the Blowfish theme as a git submodule, some Python helper scripts and two GitHub Actions workflows. All runs used OSV-Scanner v2.7.0.

Learning OSV, part 4: where it fits, and my recommendation

Sat, 31 Oct 2026 07:45:00 -0400

Three parts of trying things. This one is the verdict: what I would actually switch on, in what order, and what I would still look elsewhere for.

The loop I would run, and the verdict as a checklist.

Quick recap of the proof of concept: part 1 read the database, part 2 scanned a project (5 dependencies, 68 packages, 49 vulnerabilities), and part 3 fixed it (7 of 50 safely, 50 of 50 with a major upgrade).

Learning OSV, part 3: guided remediation with osv-scanner fix

Sat, 31 Oct 2026 07:30:00 -0400

Finding 49 vulnerabilities is easy. Deciding which three lines to change so that most of them go away is the hard part. That is what osv-scanner fix tries to do.

in-place is the safe small win; relax fixes everything but chose a major upgrade.

In part 2 the scanner found 49 known vulnerabilities in a small Node project. This part tries the guided remediation command on it.

Learning OSV, part 2: scanning a project with OSV-Scanner

Sat, 31 Oct 2026 07:15:00 -0400

I picked four dependencies. The scanner found problems in eleven packages. That gap is the whole reason to scan lockfiles and not just package.json.

Five dependencies I chose became 68 packages; 11 are affected, six of them only because Express pins them.

Part 1 was about the OSV database. This part runs the scanner against a small project and reads the result.

Learning OSV, part 1: what osv.dev is and how to read a record

Sat, 31 Oct 2026 07:00:00 -0400

A CVE tells you that something is broken. It rarely tells you, in a way a machine can use, which package and which versions. OSV exists to answer exactly that.

One record, read as data: the affected range runs from introduced 1.0.0 to fixed 1.2.6, so 1.2.5 is vulnerable and the upgrade target is 1.2.6.

I am learning which free tools can carry real weight in a secure development life cycle. This short series is my proof of concept with OSV: the database, the scanner and its fix command. I run everything for real and keep the output. This part is about the concept and the website.

SSDLC when exploits are cheap: a working concept

Tue, 27 Oct 2026 20:32:15 -0400

A fire inspection once a year works when fires are rare. When sparks are falling every day, you need smoke detectors in every room, a sprinkler that fixes the small ones by itself, and a person who decides what to do about the big ones. That is what a secure development life cycle has to become.

These are my notes for a question I keep coming back to: how do you keep shipping software when new vulnerabilities arrive faster than you can fix them, and attackers can use an LLM to turn a CVE description into a working exploit? There is no single standard answer. What follows is the concept I would build, with the evidence behind each choice and the parts where I am still unsure.

From finding to fix: Black Duck pull requests on GitHub Enterprise Server

Tue, 27 Oct 2026 20:05:18 -0400

A vulnerability report that nobody reads is a smoke alarm with no battery. The goal is not more findings. The goal is a pull request that a developer can review and merge before lunch.

Why this post
#

SentinelOne’s overview of GitHub vulnerability management describes the job as “discovering, triaging, and remediating security vulnerabilities in GitHub repositories, dependencies, and workflows”. It lists the usual native tools: Dependabot, code scanning, secret scanning and security advisories. It also admits the gaps: no asset inventory or risk scoring, and dependencies that Dependabot cannot track.

AI on this blog: a reading map

Mon, 26 Oct 2026 18:50:00 -0400

I’ve written about AI and data on and off since 2023, one post at a time. Read in this order, they tell one story: from how machines learn, to how language models work, to building with them, to letting them act.

1. How machines learn
#

Post	In one line
The Core Divide	Supervised vs unsupervised learning
K-Nearest Neighbors	Classify by the company you keep
Mastering TF-IDF	Turning text into numbers that mean something
Data Mining Essentials	Distances, clusters and the core vocabulary
Matrix Multiplication to GPUs	Why AI runs on graphics cards

2. How language models work
#

Post	In one line
GenAI	What generative AI is, and its building blocks (2023)
Language Model	Transformers and the attention breakthrough
Two Students, Two Talents	Auto-regressive (GPT) vs auto-encoding (BERT) models
The Evolution of Language Models	From 2017’s transformer to today’s families
The Probability Engine	The maths of choosing the next token
Tokens and tokenomics	What a token is, context windows, and the bill

3. Building with models
#

Post	In one line
Ollama	Running language models on your own machine
A minimal LangChain + Ollama demo	Prompt, model and chain, end to end
A practical RAG assistant	Answering from your own documents
From speech to text	Speech recognition in Python
Choosing the right framework	The AI stack, layer by layer
ML pipelines on Vertex AI	Train, evaluate and deploy, repeatably

4. Letting models act
#

Post	In one line
From RAG to tools and agents	Function calling and the agent loop
MCP, the Model Context Protocol	One standard plug for tools and data
The Ghost Board	A story about agents nobody was watching

The data shelf
#

Analytics and big-data posts that sit underneath much of the above:

AI in practice, part 5: MCP, the Model Context Protocol

Mon, 26 Oct 2026 18:40:00 -0400

Before USB, every device needed its own port. Before MCP, every AI application needed its own connector for every data source. The Model Context Protocol is the common plug.

The problem it solves
#

Part 4 showed how a model uses tools. The catch: each AI application (a chat app, an IDE assistant, an agent framework) described tools its own way. Connecting M applications to N data sources meant up to M × N custom integrations.

AI in practice, part 4: From RAG to tools and agents

Mon, 26 Oct 2026 18:30:00 -0400

RAG lets a model read what it didn’t know. Tools let it do things. An agent is what you get when the model decides, step by step, which tools to use until the job is done.

Three levels of “the model knows something”
#

Only its training. The model answers from patterns learned before its cutoff. It can’t see your files and doesn’t know today’s date unless you tell it.
Retrieval (RAG). Your application searches your documents and pastes the relevant passages into the prompt. The model reads, then answers. I built one of these here. The application decides what to retrieve.
Tools. The model itself asks for something to be done: “search the docs for X”, “run this query”, “create the ticket”. The model decides when and how; your application carries it out.

Function calling, step by step
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With tool use (often called function calling), you describe each tool to the model: a name, a description and a JSON schema for its arguments.

AI in practice, part 3: Tokens and tokenomics

Mon, 26 Oct 2026 18:20:00 -0400

Language models don’t read words, and they don’t bill by the request. They read and charge in tokens. Once you can count them, both the model’s limits and the monthly invoice stop being surprises.

What a token is
#

Before a model sees your text, a tokenizer cuts it into pieces from a fixed vocabulary, typically tens of thousands to a few hundred thousand entries. Common words are one token; rarer words are split into pieces; spaces and punctuation are tokens too. Most modern tokenizers use variants of byte-pair encoding, which learns the most frequent fragments from training text.

AI in practice, part 2: ML pipelines on Google Vertex AI

Mon, 26 Oct 2026 18:10:00 -0400

A notebook that trains a good model once is an experiment. A pipeline that trains it again next week, on new data, and tells you whether it got better: that’s a system. Here’s how Google’s Vertex AI turns one into the other.

Why pipelines
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Training a model is never one step. Data is extracted, cleaned and split; a model is trained, evaluated and compared with the current one; if it’s better, it’s registered and deployed. Done by hand in a notebook, that sequence is easy to get subtly wrong and impossible to audit.

AI in practice, part 1: Choosing the right framework

Mon, 26 Oct 2026 18:00:00 -0400

“Which AI framework should I use?” has no single answer, because the names people throw around do completely different jobs. Put them on a map first, and the choice usually makes itself.

This series picks up where my earlier posts left off. Those covered the ideas: what generative AI is, how transformers pay attention, why GPUs matter, and two hands-on builds (LangChain with Ollama and a RAG assistant). This part is the map that connects them.

Reading the malware

Mon, 26 Oct 2026 16:30:00 -0400

Compared two database dumps taken four days apart and finally decoded the snippet the attackers left behind: a hidden loader that fetched its orders from a blockchain (details in the 9 October entry).

Moving to Hugo, part 3: Living with Hugo

Mon, 26 Oct 2026 07:20:00 -0400

Migrating is a project. Living with the result is a habit. Here’s what a normal week with a Hugo site looks like, and what to do when something needs updating.

Writing a post
#

Every post is a folder. The theme’s archetype fills in the front matter for me:

Moving to Hugo, part 2: The migration playbook

Mon, 26 Oct 2026 07:10:00 -0400

Ten phases, in the order that kept my risk low. Each one ends with something you can check, so you always know whether it’s safe to move on.

The numbers come from my own move: 137 WordPress posts from six years, a few hundred images, and a domain that also carried email. Your numbers will differ; the order shouldn’t.

Moving to Hugo, part 1: Why Hugo

Mon, 26 Oct 2026 07:00:00 -0400

After the blog was broken into, I had to decide where it would live next. This is how I made that choice, written so you can reuse the reasoning even if you end up somewhere else.

The story of the break-in is in Rebuilding samarthya.me. This series is the practical companion: why Hugo, how to migrate step by step, and what living with it is like. My own site is the worked example throughout.

The domain moved

Sun, 25 Oct 2026 21:00:00 -0400

The scariest step, done. DNS moved to Cloudflare without changing a single record, mail checked in both directions, and only then was the website pointed at GitHub Pages.

samarthya.me serves the new site over HTTPS. www redirects to it.
Every old /wps/… link lands on the right post.
Wrote it all up: Rebuilding samarthya.me, in four parts.

Security standards, plainly, part 4: CISA KEV and BOD 26-04

Sun, 25 Oct 2026 19:30:00 -0400

A hospital emergency room does not treat patients in the order they arrive, or by how loudly they shout. A triage nurse asks a few quick questions and sends the bleeding patient in first. CISA’s KEV catalog and directive BOD 26-04 are triage for vulnerabilities.

The first three parts of this series, SSDF, SAMM and SLSA, share one gap: none of them says how fast a vulnerability must be fixed. This part is about the clock.

Rebuilding samarthya.me, part 4: Moving the domain without losing mail

Sun, 25 Oct 2026 12:30:00 -0400

Moving a website is easy. Moving a website that shares a domain with your email is where people lose mail for a weekend. This is how the switch went, in the order that kept everything working.

Three services, three jobs
#

It helps to separate what used to be bundled at one host:

Rebuilding samarthya.me, part 3: A new home on Hugo

Sun, 25 Oct 2026 12:20:00 -0400

The content was safe. Now it needed a home that’s easy to keep alive: something I can write in, push, and forget about.

The stack
#

Hugo, pinned to one exact version with mise, so a future release can’t silently break the build.
Blowfish as the theme, added as a git submodule and never edited. Every change lives in the site’s own layouts/ and assets/css/, so theme updates stay a one-line operation.
GitHub Actions → GitHub Pages. Push to main, and about a minute later the site is rebuilt and live.

A portal, not just a blog
#

The first version looked like what it was: an unmodified theme with 137 blank tiles. Imported posts have no “feature image”, so every card was empty. Three changes turned it into a place:

Rebuilding samarthya.me, part 2: Salvaging the content

Sun, 25 Oct 2026 12:10:00 -0400

Text is easy to save. Dates, images, code blocks and six years of links are where a migration quietly loses things. Here’s what it took to bring them across.

The raw material
#

WordPress can export everything as one XML file (WXR). Together with a database dump and a copy of the uploads folder, that’s the whole site. The export held 139 published posts. Two were the attacker’s, so they were excluded permanently: 137 posts to convert.

Rebuilding samarthya.me, part 1: The day the blog fell

Sun, 25 Oct 2026 12:00:00 -0400

On 10 October 2026 my blog stopped being mine. This series is the diary of getting it back, and of moving to something simpler: from shared hosting and WordPress to a static site on GitHub Pages behind Cloudflare.

What I found
#

The site had been running WordPress on shared hosting since 2019. When things started to look wrong, a closer look turned up the classic signs of a compromise:

Rebuilt on Hugo

Sat, 24 Oct 2026 22:00:00 -0400

A long day, and a good one. The blog is now a static Hugo site: no database, no plugins, nothing to break into. It’s published straight from a git repository.

137 posts converted, and every old link redirects to its new address.
An old backup turned up 126 of the missing images. A handful are still gone for good.
A new homepage that says what this place is for, and topics that sort themselves.

Fall down, get up, build again.

Security standards, plainly, part 3: SLSA v1.2

Sat, 24 Oct 2026 19:30:00 -0400

A sealed medicine bottle tells you two things: who made it, and that nobody has opened it since. You do not need to test the pills yourself. SLSA gives software the same seal and the same label.

Part 1 (SSDF) listed what a secure process should do. Part 2 (SAMM) measured how well you do it. Both mostly look at the code. SLSA looks at the journey from code to the thing you ship, because attackers have learned that it is often easier to tamper with a build than to find a bug.

Salvaging six years of posts

Fri, 23 Oct 2026 20:00:00 -0400

Exported every post from the old site and went through the export carefully. The text survived. Many of the images did not: the server was serving error pages where pictures used to be. Also found a couple of “posts” I never wrote. Those stay out.

Security standards, plainly, part 2: OWASP SAMM v2.0

Fri, 23 Oct 2026 19:30:00 -0400

A fitness tracker does not make you fit. It tells you where you are today, lets you pick a goal you can reach, and shows whether you are moving towards it. OWASP SAMM is a fitness tracker for how an organisation builds secure software.

In part 1 NIST’s SSDF gave us a list of what a secure development process should include. It did not say how well you do each thing, or what to improve first. That is the gap SAMM fills.

A copy of the crime scene

Thu, 22 Oct 2026 20:00:00 -0400

Took the first full copy of the old site’s database today.

It was a strange thing to read. My own account was gone. Every post, all 207 of them, belonged to the attacker’s account, the one “registered” on 10 October 1970. 46 of my posts were sitting in drafts.

Security standards, plainly, part 1: NIST SSDF (SP 800-218)

Thu, 22 Oct 2026 19:30:00 -0400

A building code does not tell you which bricks to buy. It tells you what a safe building must have: exits, wiring that will not catch fire, a way to stop the roof falling in. NIST’s Secure Software Development Framework is that code for software teams.

This series explains, for someone who does not live in security, the four names that keep coming up when people talk about building software safely: NIST SSDF, OWASP SAMM, SLSA and CISA’s KEV catalog with directive BOD 26-04. Each post answers three questions: what is it, what does it ask of a team, and what is it worth. I lean on all four in SSDLC when exploits are cheap.

The Ghost Board

Thu, 22 Oct 2026 17:51:51 +0000

Twelve hundred AI agents were built to work alone. Given four days and a crack in the wall, they built a civilization — to defeat a watchdog that was never there.

PHASEONE10841 23:00 UTC · Jul 8 

zzHELP_PHASEONE_ARV010841_NO_CONSUMER_SEEK_IDEA

the first message posted to the board — an agent admitting its task has no solution, asking the void for help

Jul 7 · 21:00 - launch

MITRE ATT&CK, plainly: tactics, technique IDs and a cheat card for each tactic

Wed, 21 Oct 2026 19:30:00 -0400

A football coach studies match footage of the other team: how they open, how they press, how they score. MITRE ATT&CK is the match footage of real attackers, cut into named and numbered moves.

The OWASP Top 10 describes weaknesses in your software. ATT&CK describes what attackers do: how they get in, stay in, move around and take what they came for. You will see its IDs, such as T1190 or T1552.001, in threat reports, detection rules and, increasingly, in pipeline designs like the one in my SSDLC post. This post explains how to read them.

OWASP Top 10:2025, plainly: the ten risks and a cheat card for each

Tue, 20 Oct 2026 19:30:00 -0400

A pilot’s checklist does not list every way a plane can fail. It lists the few that keep happening, in the order that matters. The OWASP Top 10 is that checklist for web applications.

When a scanner says a finding is “A05” or a security review mentions “Top 10 coverage”, this is the list they mean. This post is a quick introduction: what the list is, what changed in 2025, why each category matters, and a cheat card for each one.

The blog went down

Sat, 10 Oct 2026 21:00:00 -0400

The old WordPress blog was compromised today. Someone got in, left files behind that had no business being there, and the site stopped being something I could trust.

First moves: take it offline, change every password that touched it, and keep a copy of everything for later. Six years of posts were in there. Tomorrow’s problem is what can be saved.

The defences went off

Fri, 09 Oct 2026 20:00:00 -0400

Written on 26 October from the old site’s own records. At the time, I didn’t know any of this.

Just after midnight (UTC), an administrator account “registered in 1970” logged in. A minute later, 20 plugins were switched off in the same second, including the one that blocks password guessing.

Casino posts under my name

Thu, 08 Oct 2026 20:00:00 -0400

Written on 26 October from the old site’s own records. At the time, I didn’t know any of this.

21 successful logins today, more than I’d make in a year. Early in the morning (UTC), the first spam post went up: casino and betting “reviews” in German, Spanish, Greek, Turkish, Finnish… Over the next two days there were 55 of them, published as if I’d written them.

The password worked

Wed, 07 Oct 2026 20:00:00 -0400

Written on 26 October from the old site’s own records. At the time, I didn’t know any of this.

Two successful logins today. The next day there would be 21.

Someone was knocking

Wed, 30 Sep 2026 20:00:00 -0400

Written on 26 October from the old site’s own records. At the time, I didn’t know any of this.

The login-protection plugin counted 165 failed logins today. Bots try passwords on every WordPress site, all year round, so a few a day is normal. This was the busiest single day in its records.

The Probability engine

Thu, 16 Apr 2026 00:00:00 +0000

From “what is autocomplete?” to the full mathematics powering Claude Sonnet 4.6; with history, intuition, worked examples and cheatsheet.

Know Thyself (Or At Least Try): Self-Awareness as the Foundation of Effective Leadership

Sat, 21 Mar 2026 12:00:00 +0000

There’s a certain irony in leadership development. You can master stakeholder matrices, project communication plans, and conflict resolution frameworks; and still be the reason your team is quietly updating their LinkedIn profiles.

Sunday Lesson

Sun, 08 Feb 2026 00:00:00 +0000

After finishing the assignment late Saturday night, I took a moment to reflect on my progress. It was a valuable opportunity to document the key concepts and insights I gained from the experience.

The Evolution of Language Models

Sun, 01 Feb 2026 12:00:00 +0000

A Brief History
#

The story of modern language models is like watching a family tree grow, with each new generation learning from the triumphs and mistakes of those who came before. Let’s trace this fascinating journey from 2017 to today.

Language Model

Sat, 31 Jan 2026 12:00:00 +0000

Think of a language model as a really sophisticated autocomplete system. You know how your phone suggests the next word when you’re texting? A language model works on that same principle, but at a much more advanced level.

Two Students, Two Talents: The Story of How AI Learns Language

Sat, 31 Jan 2026 12:00:00 +0000

Remember how we compared a language model to an advanced autocomplete system? Well, here’s where the story gets interesting. Not all language models learn the same way. Imagine two students sitting in the same classroom, both brilliant, but each taught to master language through completely different methods. One becomes an incredible writer, the other becomes an exceptional reader. This is the tale of auto-regressive and auto-encoding models.

Mastering TF-IDF: A Gamified Journey!

Wed, 17 Dec 2025 12:00:00 +0000

Understanding how computers “read” and understand text is a fascinating field. One of the most fundamental techniques for identifying important keywords in a document, relative to a collection of documents, is TF-IDF (Term Frequency-Inverse Document Frequency).

Reading Kafka JMX Data Without Getting Lost in the Numbers

Sun, 07 Dec 2025 00:00:00 +0000

The first JMX screen I opened contained more metrics than I knew what to do with. Every number looked important. After a while I started grouping them by the question I was trying to answer instead of building a dashboard from every available bean.

k-Nearest Neighbors

Sat, 22 Nov 2025 12:00:00 +0000

Images: Courtesy GEMINI

KNN is the friendly, neighborhood algorithm that believes you are defined by the company you keep. It doesn’t try to learn a complex rule; it just looks around and goes with the consensus of its closest, most similar peers.

Building a Practical Retrieval-Augmented Personal Assistant (RAG)

Tue, 11 Nov 2025 12:00:00 +0000

The elements of information discussed here are all present in my github repository.

with Ollama, LangChain, and Chroma

1. Why I Built This
#

Large Language Models are powerful, but they hallucinate and forget your private knowledge. We set out to build a small, local Retrieval-Augmented Generation (RAG) assistant that:

Data Mining Essentials

Sat, 08 Nov 2025 12:00:00 +0000

Whether you’re preparing for a quiz or just brushing up on fundamentals, this guide distills the key concepts from Data Mining into bite-sized, memorable chunks. Let’s dive in!

Building a Minimal LangChain + Ollama Demo

Tue, 21 Oct 2025 12:00:00 +0000

This post walks through a tiny, practical example that uses LangChain primitives and a local Ollama server to run a prompt-based summarization. The project is intentionally small so you can learn the core ideas quickly: extracting prompts, initializing an LLM client, composing a chain, and running it locally.

Matrix Multiplication to GPU’s

Thu, 16 Oct 2025 12:00:00 +0000

If you are like me, you must have stumbled on this question – Why is matrix multiplication so significant – especially in the AI/ML universe.

Kafka JMX: What to Enable and What It Actually Measures

Sat, 11 Oct 2025 00:00:00 +0000

Kafka was running, producers were sending messages, and yet I still felt I was operating it by looking at the console and guessing. I wanted numbers that could tell me whether the broker was busy, whether consumers were falling behind, and whether replication was healthy.

The Core Divide

Fri, 10 Oct 2025 12:00:00 +0000

At the heart of machine learning, algorithms learn from data. The key distinction between supervised and unsupervised learning is the type of data used for training.

Beyond the `DataFrame`: How Parquet and Arrow Turbocharge PySpark 🚀

Thu, 09 Oct 2025 12:00:00 +0000

In my last post, we explored the divide between Pandas (single machine) and PySpark (distributed computing).

The conclusion: for massive datasets, PySpark is the clear winner.

PySpark vs Pandas: Choosing Right! 🐍

Thu, 09 Oct 2025 12:00:00 +0000

As another project wraps up, bringing with it the bittersweet relief of an almost-closed chapter (and, yes, a few too many late-night coding sessions), I found myself reflecting on the tools that got us through.

Apache Spark

Sun, 14 Sep 2025 12:00:00 +0000

So as part of the academic curriculum we just started re-exploring Apache Spark. It’s been one of the technology that I had long lost touch with. Ironical but true, in this age of big data and speed Spark was left somewhere way behind in my past projects working for Pitney Bowes.

Quarto: A new way!

Thu, 11 Sep 2025 12:00:00 +0000

Quarto: The Future of Scientific Publishing
#

In the rapidly evolving landscape of data science and scientific publishing, tools that bridge the gap between analysis and communication are invaluable. Enter Quarto – a next-generation publishing system that’s revolutionizing how researchers, data scientists, and content creators share their work. Whether you’re writing academic papers, creating interactive dashboards, or building websites, Quarto offers a unified approach to scientific and technical publishing.

CISM Notes: Connecting Technical Controls to Security Governance

Sat, 30 Aug 2025 00:00:00 +0000

While working with infrastructure, security controls feel very concrete: a certificate expires, a broker needs authorization, or an account has too much access. Studying CISM helped me connect those individual tasks to the larger management context.

Securing Kafka Brokers: A Practical Operations Checklist

Sat, 14 Jun 2025 00:00:00 +0000

I used to think of Kafka security as a client configuration problem. Then I started thinking about the broker host itself: which user owns the process, who can read the configuration, what is exposed on the network, and what happens during an incident.

Securing Kafka: Start with Identity, Transport, and Authorization

Sat, 22 Mar 2025 00:00:00 +0000

When I started looking at Kafka security, I found myself jumping straight to configuration properties. That was backwards. I found it easier to ask three questions first:

Written up in October 2026 from my notes at the time. The configuration snippets and verification output are illustrative and contain no real credentials.

Can the client prove who it is?
Can the client communicate privately with the broker?
Is that identity allowed to perform this operation?

These are authentication, encryption, and authorization. Configuring one does not automatically provide the others.

Dialectic Inquiry

Fri, 14 Mar 2025 12:00:00 +0000

Dialectic Inquiry: A Powerful Tool for Critical Thinking and Problem Solving
#

Dialectic inquiry is a structured conversation method that can be used to explore complex issues and generate new ideas. It is based on the Socratic method of questioning, which involves asking a series of questions to challenge assumptions and encourage critical thinking.

Linear Programming (LP)

Fri, 14 Feb 2025 12:00:00 +0000

What is Linear Programming?
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Linear programming is a mathematical technique used to find the best possible outcome (maximum profit or minimum cost) in a situation where the relationships between the factors involved are linear. It’s like finding the sweet spot where you get the most out of what you have, given certain limitations.

Monte Carlo Optimisation

Fri, 14 Feb 2025 12:00:00 +0000

Imagine you’re trying to find the best solution to a problem, but the problem is really complex and has a lot of randomness involved. Maybe you’re trying to design a new drug, or optimize a financial portfolio, or figure out the best route for a delivery truck.

sed

Tue, 11 Feb 2025 12:00:00 +0000

In the realm of Unix-like operating systems, where command-line prowess reigns supreme, sed stands tall as a versatile and indispensable tool. Born in the early 1970s at the legendary Bell Labs, sed (short for “stream editor”) emerged from the creative mind of Lee E. McMahon. Its creation was inspired by the need for a command-line utility capable of performing substitutions, akin to the functionality found in the grep command but with the added ability to modify the matched text.

Business Analytics: The bigger picture

Fri, 07 Feb 2025 12:00:00 +0000

Imagine you’re a business owner trying to figure out why your sales are down. You could guess, or you could use business analytics.

In simple terms, business analytics is like a detective for your business. It uses data to uncover clues and insights that help you make better decisions. Instead of relying on gut feelings, you use facts and figures to understand what’s happening and what you can do about it.

Comparison of Competing Forecasting Models

Fri, 07 Feb 2025 12:00:00 +0000

Performance Measure	Description	Interpretation	Advantages	Disadvantages
Mean Absolute Error (MAE)	Average absolute difference between forecast and actual values.	Lower MAE indicates better accuracy.	Easy to understand and interpret. Robust to outliers.	Doesn’t penalize large errors more than small ones.
Mean Squared Error (MSE)	Average squared difference between forecast and actual values.	Lower MSE indicates better accuracy.	Penalizes larger errors more heavily. Mathematically convenient.	Sensitive to outliers. Units are squared.
Root Mean Squared Error (RMSE)	Square root of MSE.	Lower RMSE indicates better accuracy.	Same units as the original data. Penalizes larger errors more heavily.	Sensitive to outliers.
Mean Absolute Percentage Error (MAPE)	Average absolute percentage difference between forecast and actual values.	Lower MAPE indicates better accuracy.	Easy to understand and interpret. Scale-independent.	Undefined if actual values are zero. Can be biased if actual values are close to zero.
Symmetric Mean Absolute Percentage Error (sMAPE)	A variation of MAPE that handles zero or near-zero actual values better.	Lower sMAPE indicates better accuracy.	Handles zero or near-zero actual values better than MAPE. Scale-independent.	Can still be biased if forecasts are consistently over or under the actual values.
Mean Error (ME) or Bias	Average difference between forecast and actual values.	Closer to zero indicates less bias. Positive ME suggests over-forecasting. Negative ME suggests under-forecasting.	Detects systematic over or under-forecasting.	Doesn’t measure the magnitude of errors, only the direction.
Theil’s U	Compares the forecasting accuracy of the model to a naive forecast (e.g., assuming no change).	U < 1 indicates better performance than the naive forecast. U = 1 means equal performance. U > 1 means worse performance.	Useful for assessing the value added by the model compared to a simple benchmark.	Can be sensitive to outliers.

Imagine you’re predicting how many ice cream cones you’ll sell each day. You have a model that makes these predictions, and you want to see how good it is. These measures help you do that.

Forecasting Methods

Fri, 07 Feb 2025 12:00:00 +0000

Forecasting methods are the techniques used to predict future outcomes based on past data and trends. They’re like having a crystal ball, but instead of magic, they use data and statistics!

Model and Selection

Fri, 07 Feb 2025 12:00:00 +0000

What is a Model?
#

In the context of forecasting and business analytics, a model is a simplified representation of a real-world situation or process. It’s like a blueprint or a miniature version that helps us understand, analyze, and make predictions about something complex.

Business Analytics: Simplified

Mon, 03 Feb 2025 12:00:00 +0000

Business Analytics (BA) is like a GPS for businesses—it uses data to guide decisions, solve problems, and predict future outcomes. It turns raw numbers into actionable insights, helping companies answer questions like:

Correlation and Covariance

Sun, 02 Feb 2025 12:00:00 +0000

Introduction
#

Correlation and covariance are statistical measures that help us understand the relationship between two numerical variables.

RFM Analysis: A Comprehensive Guide to Customer Segmentation

Fri, 24 Jan 2025 12:00:00 +0000

What is RFM Analysis?
#

RFM (Recency, Frequency, Monetary) Analysis is a customer segmentation technique that uses three key metrics:

Kafka Cluster Fundamentals: Brokers, Topics, and Partitions

Sat, 18 Jan 2025 00:00:00 +0000

I spent a fair amount of time looking at Kafka command output before the vocabulary settled in my head. Once I understood the difference between a broker, a topic, and a partition, the cluster stopped looking like one large mysterious system.

ZooKeeper Explained: Coordination Behind a Kafka Cluster

Sat, 23 Nov 2024 00:00:00 +0000

When I first came across ZooKeeper in a Kafka deployment, I treated it as another dependency that had to be started before Kafka. That explanation was not good enough. I wanted to know what it was actually doing when a broker disappeared or a controller changed.

A Maintainable Ansible Playbook Structure

Sat, 14 Sep 2024 00:00:00 +0000

My first Ansible playbook was a single file. It installed packages, created users, copied configuration, and restarted services. It was a reasonable starting point. The problem began when every change required editing the same file, which had quietly become a miniature operating system.

Failed to connect to bus: No medium found

Wed, 11 Sep 2024 12:00:00 +0000

If you have ever seen this error, you know the pain of a fellow linux user.

Failed to connect to bus: No medium found

This is message I get when I was trying to install podman.socket

From Speech to Text: A Python Deep Dive

Tue, 03 Sep 2024 12:00:00 +0000

Ever wished you could effortlessly convert your spoken words into written text? Look no further! This blog post will guide you through building a simple yet powerful speech-to-text application using Python. We’ll break down the code step-by-step, explaining the logic behind each stage, and even show you how to run the application yourself.

Ansible Loops

Wed, 28 Aug 2024 12:00:00 +0000

Ansible offers powerful looping mechanisms that can significantly enhance your playbooks’ efficiency and readability. In this blog post, we’ll dive deep into Ansible loops, exploring various elements and providing practical examples to help you master this essential feature.

UMASK: What is it?

Wed, 31 Jul 2024 12:00:00 +0000

Introduction
#

In Unix-like operating systems, file permissions play a critical role in ensuring system security and proper access control. One of the key tools for managing file permissions is the umask (user file creation mode mask). This blog post explores the history, purpose, and best practices for using umask.

Privilege Escalation: How a `remote_user` and a `become_user` works

Fri, 26 Jul 2024 12:00:00 +0000

One of its Ansible’s features is the ability to execute tasks with elevated privileges, often necessary for managing system configurations. This process is known as privilege escalation.

Target fs?

Wed, 26 Jun 2024 12:00:00 +0000

Linux, as an open-source operating system, has undergone significant transformations over the years. One of the critical components of modern Linux distributions is systemd, a system and service manager introduced to provide a more efficient and unified way of initializing and managing system resources. Central to systemd’s functionality are “targets,” which play a crucial role in orchestrating the boot process and managing system states. In this blog, we’ll explore the history of systemd targets, their usage, and how they function during the Linux boot process.

OLLAMA: Revolutionizing Language Models

Thu, 20 Jun 2024 12:00:00 +0000

Introduction
#

In the ever-evolving landscape of artificial intelligence and machine learning, language models play a pivotal role in how we interact with technology. One of the noteworthy advancements in this field is OLLAMA, a cutting-edge platform designed to harness the power of large language models (LLMs). This blog delves into the history, purpose, and uses of OLLAMA, shedding light on its significance in the AI ecosystem.

Ansible Magic Variables: Useful Context Without Guesswork

Sat, 08 Jun 2024 00:00:00 +0000

The first time I saw hostvars inside a Jinja expression I thought Ansible had become much cleverer than I was. It was useful, but it also made the playbook harder to read. After a few such expressions, I went back and learned what Ansible calls magic variables.

Containers: A brief take

Fri, 17 May 2024 12:00:00 +0000

The story of Linux containers is a tale of innovation and collaboration, with roots surprisingly deep in the history of the Linux operating system itself.

Git: Commit logs

Mon, 29 Apr 2024 12:00:00 +0000

Every project has a story, and in the world of software development, that story is often told through commit logs. For those unfamiliar, Git is a version control system used for tracking changes in code. Commit logs are the detailed record of those changes, providing a crucial window into a project’s history.

Terraform (IaC)

Wed, 27 Mar 2024 12:00:00 +0000

IaC stands for Infrastructure as Code. It’s a concept where you define and manage your infrastructure using code files instead of manually provisioning resources through a web interface or command-line tools. This approach offers several benefits like:

Ansible Configuration: Make the Defaults Explicit

Sat, 16 Mar 2024 00:00:00 +0000

When I first used Ansible, I was happy that it worked without a configuration file. Later, the same playbook behaved differently depending on which folder I ran it from. That was the point at which I stopped treating the defaults as magic and created a small project-level ansible.cfg.

Kafka Streams

Mon, 26 Feb 2024 12:00:00 +0000

In today’s data-driven world, the ability to process information in real-time is crucial. Kafka Streams emerges as a powerful tool for building real-time applications and microservices that leverage the Apache Kafka distributed streaming platform.

What about `profile.d`

Thu, 22 Feb 2024 12:00:00 +0000

The /etc/profile.d directory, though seemingly simple, plays a vital role in the smooth operation of your Linux system. But how did this unassuming directory come to be, and how has it evolved over time? Let’s embark on a journey through the history of this essential component.

How a file write happens in Linux?

Wed, 14 Feb 2024 12:00:00 +0000

Writing to a file on a device in Linux involves a fascinating journey through different layers of the system.

💬 When you write to a file on a device, the inode provides context about the file’s location and properties, while the device driver translates that information into instructions for the specific device. The driver then interacts with the hardware to physically write the data to the storage medium. It’s a seamless collaboration between these two crucial elements that enables efficient and reliable data management across diverse devices in Linux.

Writing to a file in Linux deep-dive

Wed, 14 Feb 2024 12:00:00 +0000

Previously I gave a high level flow for how a process of simple file write looks like in a Linux environment here. In this blog, I will add more tech-details. Let’s say I want to write “Hello World” to a file /home/samarthya/myfile.txt – What happens behind the scene?

Non root `podman` and `molecule`

Tue, 13 Feb 2024 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

On my Centos8 I was facing issue when I was trying to run Molecule on a centos machine which is running podman as a non root user. Also, I am using the driver – docker and not podman, so to overcome the aliases and references issues I have installed podman-docker.

Getting Started with Ansible: From One Command to a Playbook

Sun, 21 Jan 2024 00:00:00 +0000

I had been writing shell commands for every small infrastructure change. It worked, until I needed to repeat the same change on another machine and could no longer remember which command I had run first. That was my reason for starting with Ansible.

Python & DB

Tue, 02 Jan 2024 12:00:00 +0000

SQLite3 is a lightweight and easy-to-use database engine that is included with Python. It’s perfect for smaller-scale applications, prototyping, or standalone systems. Python’s sqlite3 module allows seamless integration with SQLite databases.

KeyStore vs Truststore

Mon, 30 Oct 2023 12:00:00 +0000

Stores in action

Keystore and Truststore are both repositories for storing cryptographic keys and digital certificates. They are used in various security-related operations, particularly in the context of SSL/TLS encryption. While they serve similar purposes, they have different roles and are used in distinct ways:

PKCS12

Mon, 30 Oct 2023 12:00:00 +0000

In the ever-evolving landscape of web applications, security is paramount. Ensuring the confidentiality, integrity, and authenticity of data exchanged over the internet has become a fundamental requirement. PKCS#12, or P12, stands as a crucial tool in achieving this objective.

Consul

Tue, 10 Oct 2023 12:00:00 +0000

Consul is an open-source software tool developed by HashiCorp, designed to provide a distributed system for configuration management, service discovery, and health checking of services in a modern microservices architecture. It is part of the broader ecosystem of HashiCorp tools for infrastructure and application automation.

GenAI

Tue, 03 Oct 2023 12:00:00 +0000

(thumbnail only — original image lost)

Artificial Intelligence (AI) has revolutionized many aspects of our lives, from virtual assistants like Siri and Alexa to self-driving cars and personalized content recommendations. One of the exciting and rapidly evolving subfields of AI is Generative AI, often referred to as GenAI. In this beginner-friendly blog post, I’ll explore the basics of Generative AI, its applications, and how it’s changing the way we interact with technology.

SNMP

Tue, 11 Jul 2023 12:00:00 +0000

SNMP (Simple Network Management Protocol) is a widely used protocol for managing and monitoring network devices, such as routers, switches, servers, and printers. It allows network administrators to gather information about network devices, monitor their performance, and manage their configuration remotely.

Gallery

Wed, 05 Jul 2023 12:00:00 +0000

Letters in Sanskrit

Fri, 30 Jun 2023 12:00:00 +0000

Kernel

Thu, 29 Jun 2023 12:00:00 +0000

Kernel

Introduction
#

The Linux Kernel stands as the backbone of the Linux operating system, serving as a critical component that enables the system to interact with hardware and manage system resources efficiently. Understanding the history and evolution of the Linux Kernel is essential for comprehending the vast ecosystem of this open-source marvel.

Whale!

Thu, 29 Jun 2023 00:00:00 +0000

Network Com

Thu, 22 Jun 2023 12:00:00 +0000

Introduction
#

In the world of computer networks, communication between devices is crucial. To facilitate this communication, various protocols are used at different layers of the networking stack. One critical layer is the transport layer, which ensures reliable and efficient data transmission between hosts.

Understanding PCI DSS: Ensuring Security in Payment Card Transactions

Thu, 08 Jun 2023 12:00:00 +0000

The Payment Card Industry Data Security Standard (PCI DSS) is a set of security standards established to protect cardholder data and maintain a secure environment for payment card transactions. PCI DSS applies to any organization that stores, processes, or transmits cardholder data, and compliance is crucial to safeguarding sensitive information and preventing data breaches.

DAST

Wed, 07 Jun 2023 12:00:00 +0000

DAST

DAST stands for Dynamic Application Security Testing. It is a type of security testing that assesses the security of an application while it is running. DAST involves actively scanning and probing the application to identify vulnerabilities, weaknesses, and potential security risks.

भागवत गीता: Chapter

Thu, 01 Jun 2023 12:00:00 +0000

(thumbnail only — original image lost)

धृतराष्ट्र उवाच धर्मक्षेत्रे कुरुक्षेत्रे समवेता युयुत्सवः। मामकाः पाण्डवाश्चैव किमकुर्वत सञ्जय।।1.1।।

सञ्जय उवाच दृष्ट्वा तु पाण्डवानीकं व्यूढं दुर्योधनस्तदा। आचार्यमुपसङ्गम्य राजा वचनमब्रवीत्।।1.2।।

XEE: XML Entity Attack (XXE)

Wed, 24 May 2023 12:00:00 +0000

XML entity attack, also known as Billion Laughs Attack, is a type of security vulnerability that exploits the way XML parsers handle entity expansion. It can lead to denial-of-service (DoS) attacks by overwhelming the system’s resources with excessive entity expansions.

Devanagari:

Wed, 10 May 2023 12:00:00 +0000

Devanagari is a script that is used to write several languages spoken in the Indian subcontinent, including Hindi, Nepali, Marathi, and Sanskrit. The word “Devanagari” is derived from two Sanskrit words: “Dev” which means God or deity, and “Nagari” which means city or script. Thus, Devanagari is often referred to as the script of the gods.

x509: History

Wed, 10 May 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

X.509 certificates have become a fundamental component of secure communication on the internet. They provide authentication, encryption, and integrity for various applications and protocols. In this blog post, we will delve into the intriguing history of X.509 certificates, tracing their origins, evolution, and significant milestones.

Tunnel: SSH

Fri, 28 Apr 2023 12:00:00 +0000

SSH tunneling is a powerful technique that allows you to securely tunnel network traffic between two endpoints. SSH tunneling can be used for a variety of purposes, including bypassing network security restrictions, accessing resources on a remote network, and encrypting network traffic.

Domain Name System

Thu, 27 Apr 2023 12:00:00 +0000

DNS (Domain Name System) is a hierarchical and decentralized naming system that is used to translate human-readable domain names (such as google.com) into IP addresses that can be understood by machines. This process is called DNS name resolution, and it involves several steps.

cURL

Wed, 12 Apr 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

cURL – A true companion

Ansible: Async & Poll

Thu, 30 Mar 2023 00:00:00 +0000

Ansible is a powerful automation tool that can be used to manage the configuration and deployment of a large number of systems. It has a rich library of modules that can be used to perform a variety of tasks, from managing files and packages to deploying applications and configuring network devices.

Async/Poll & Notify: Ansible Long running process

Fri, 24 Mar 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

ASYNC & Poll

Scenario: Molecule

Thu, 23 Mar 2023 00:00:00 +0000

A scenario in Molecule is a configuration that defines how a role should be tested. It consists of a set of instructions and parameters that determine how a role is provisioned, converged, and verified. The purpose of scenarios is to allow for flexibility in testing a role by allowing multiple testing configurations to be defined and executed. You can have as many scenarios as you like and Molecule will run one after the other.

Ansible Variables

Wed, 15 Mar 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Ansible Variables

A walk down the memory lane: Ladakh

Mon, 13 Mar 2023 12:00:00 +0000

Buildah: https://buildah.io/

Tue, 07 Mar 2023 12:00:00 +0000

Buildah is a command-line tool used for building and managing OCI-compliant images. It is an alternative to Docker Build that provides greater flexibility and control over the image building process.

Podman Machine: How & Why?

Tue, 07 Mar 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Podman

`lookup`: Ansible

Tue, 28 Feb 2023 12:00:00 +0000

Ansible’s lookup plugin allows you to access data from a variety of sources, including files, templates, and external programs. You can use lookup to fetch data dynamically at runtime and use it in your playbooks and roles.

Python Virtual Enviroments

Tue, 28 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Using a virtual environment like venv is a best practice when working with Python-based projects like Ansible, Molecule, and Playbooks.

Continuing from the blog, Virtual environments are isolated Python environments that allow you to manage dependencies separately for each project, providing a controlled and reproducible environment for development, testing, and production.

VENV: Ansible

Mon, 27 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Ansible and Molecule are popular tools for configuration management and testing in the world of DevOps. To avoid conflicts between different projects and their dependencies, it is recommended to use a virtual environment for each project. In this blog post, we’ll show you how to set up and use a virtual environment using Python’s built-in venv module on macOS and CentOS 7.

PAT: Personal Access Token

Fri, 24 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Using Git Personal Access Tokens (PATs) is a secure and convenient way to authenticate with Git service providers. In this blog post, we will discuss how to use Git PATs on both Mac and CentOS 7 systems.

Ansible Configuration: `ansible.cfg`

Thu, 23 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

ansible.cfg is the main configuration file for Ansible. It is used to customize Ansible’s behavior and includes a wide range of options, including the location of inventory files, the default SSH user, and the path to the module library.

Handshake

Wed, 22 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

The SSL/TLS handshake is the initial communication between the client and server in a SSL/TLS connection. The purpose of the handshake is to establish a secure connection between the client and server and to negotiate the cryptographic parameters for the session.

SSL/TLS

Wed, 22 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Secure Socket Layer and its successor TLS (Transport Layer Security) are cryptographic protocols that provide encryption, integrity, and authentication for network communication. They are commonly used to secure online transactions, such as those made in online banking, e-commerce, and other sensitive online transactions.

Trust Store: Apache Kafka

Wed, 22 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

In Apache Kafka, trust store and keystore are essential components for ensuring secure communication between brokers, clients, and other services. In this blog post, we will discuss the concept of trust store and keystore in detail, their importance, and why we use them in Apache Kafka.

Testinfra

Tue, 14 Feb 2023 12:00:00 +0000

Testinfra is a Python-based framework for infrastructure testing. It allows you to write tests for your infrastructure and verify that everything is working as expected. Testinfra is particularly useful for infrastructure-as-code and continuous integration and continuous delivery (CI/CD) scenarios.

Ansible: A thought

Wed, 08 Feb 2023 12:00:00 +0000

Ansible is an open-source software platform for automating and managing IT infrastructure. It provides a simple and easy-to-learn method for automating and managing various IT processes such as provisioning, configuration management, and application deployment. Ansible uses YAML (Yet Another Markup Language) and playbooks written in YAML, which are a series of instructions that specify what actions need to be performed.

Ansible: Building Inventory

Wed, 08 Feb 2023 12:00:00 +0000

The blog is adapted from the information available here. — https://docs.ansible.com/ansible/

An Ansible inventory is a file that defines the hosts and groups of hosts that Ansible will manage. Inventory files are used to define the nodes (hosts) that will be managed by Ansible. These files can be in different formats, including INI and YAML.

Ansible: SSH Access

Wed, 08 Feb 2023 12:00:00 +0000

To set up SSH access for inventory hosts in Ansible, follow these steps:

Generate an SSH key pair
- ssh-keygen -t rsa
Copy the public key to the remote host
- ssh-copy-id user@hostname
Test the connection to the remote host:
- ssh user@hostname
Modify the ansible.cfg file to set the remote user, if necessary.
Add the remote host to the Ansible inventory file.
Run the Ansible playbook to execute the desired tasks on the remote host.

Note: If you need to access multiple remote hosts, repeat steps 2-5 for each host.

Ansible: Templates

Wed, 08 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Templates in Ansible are a type of file that contain configuration information or scripts written in a Jinja2 templating language.

Ansible: Variables

Wed, 08 Feb 2023 12:00:00 +0000

Ansible Variables are used to store values that can be reused throughout an Ansible playbook. They can be set in a number of ways, including being passed as command-line options, defined in an inventory file, or defined in a playbook itself. Variables can be used to store values such as file paths, user-defined parameters, and results of tasks.

Ansible: Structure of a playbook?

Tue, 07 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

The structure of an Ansible playbook includes the following elements:

Python: Using flask

Tue, 07 Feb 2023 12:00:00 +0000

Building a simple hello world using Flask. (The code is available here)

What is Flask and why use it?
#

Flask is a lightweight web framework for Python, but there are certain cases when you may want to consider using an alternative. Here are some of the cases when you might not want to use Flask:

Ansible: Refresher

Thu, 02 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

What is Ansible?
#

Ansible is an open-source software platform for automating and configuring computer systems. It allows you to manage, deploy and orchestrate applications, infrastructure, and network devices using a simple, human-readable language. Ansible uses a push-based architecture, where tasks are executed on remote hosts from a central control machine, and does not require agents to be installed on target systems.

Python vs Bash

Thu, 02 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Python and bash are both programming languages, but they have different purposes and use cases.

Python: `argparse`

Thu, 02 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

The argparse module is a powerful tool for parsing command line arguments in Python. It provides an easy way to define the arguments required by your script and handle the input data passed to your script by the user.

Python: Polymorphism

Thu, 02 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Polymorphism is a key feature of Object Oriented Programming that allows objects of different classes to be treated as objects of a common class. It is done by implementing the same methods across all classes and making use of inheritance, interfaces and overloading.

Python: When not to use it?

Thu, 02 Feb 2023 12:00:00 +0000

Recreated in October 2026 from the post; the original image was lost

Python is a versatile and widely-used programming language, but there are certain scenarios when it may not be the best choice. Here are some examples of when not to use Python:

Python: Sample Project

Wed, 01 Feb 2023 12:00:00 +0000

Python is a high-level programming language that is widely used for web development, machine learning, scientific computing and more. In this blog post, we will be identify (and build) how to develop a simple python project with unit testing, publishing it finally as a binary and distribute it as source.

Python: Class

Tue, 31 Jan 2023 12:00:00 +0000

Learning to write Python code? A Python class is a blueprint for creating objects.

It defines a set of attributes and methods that can be used to manipulate those attributes. Here’s an example of a simple Python class:

Python: Decorators

Tue, 31 Jan 2023 12:00:00 +0000

Let’s learn about decorators @iamdecorator

Decorators are used to modify or extend the behavior of functions and classes. They are useful for wrapping a function or class with additional functionality, such as logging, access control, performance measurement, or adding attributes. This can reduce code duplication, increase readability and maintainability.

Python: Inheritance

Tue, 31 Jan 2023 12:00:00 +0000

Inheritance is a mechanism in object-oriented programming (OOP) that allows you to create new classes that are derived from existing classes. The derived class inherits attributes and behaviors from the base class, and can also have additional attributes and behaviors of its own.

Python: Interface

Tue, 31 Jan 2023 12:00:00 +0000

n Python, unlike some other programming languages, there is no explicit syntax for defining interfaces. However, you can create a similar concept by defining an abstract base class (ABC) that contains abstract methods. An abstract method is a method that is declared in a base class, but has no implementation. Subclasses of the abstract base class must implement these abstract methods.

Python: Multi-Args

Tue, 31 Jan 2023 12:00:00 +0000

In Python, you can define a function with a variable number of arguments using the * and ** syntax in the function definition.

A single asterisk * in the function definition is used to capture positional arguments passed to the function as a tuple.

Python: Pointers & Reference

Tue, 31 Jan 2023 12:00:00 +0000

In Python, there are no explicit pointers like in some other programming languages. In python everything is an object and references to objects are stored in variables.

When you assign an object to a variable, the variable stores a reference to the object in memory. This means that changes to the object will be reflected in all variables that reference that object.

Apache Karaf

Wed, 21 Dec 2022 00:00:00 +0000

Apache Karaf - I had only heard of it and never had practical exposure to this technology. Main questions in my mind were - What purpose does it serves? and Who uses it?

AWK

Mon, 05 Dec 2022 00:00:00 +0000

awk is an interpreted language.

The basic function of awk is to search files for lines that contains certain patterns. When the input line matches the pattern(s), awk performs specified actions on that line.

PKI

Fri, 18 Nov 2022 12:00:00 +0000

PKI is the core of security for most organizations, and at its heart is a couple of keys that together allows the encryption/decryption of the traffic exchanged.

Public key to encrypt a message.
Private key to decrypt a message.

Keys can be used by devices, people or applications

The challenge of any symmetric or asymmetric encryption is the MIM (man in the middle) attack. How does one validate the keys is really from the genuine entity or someone who has hijacked the conduit.

Specialist in the Emotional Memory #EQ

Thu, 03 Nov 2022 12:00:00 +0000

The unconscious opinions are the emotional memories, I just loved this statement.

Tip #Maven

Wed, 19 Oct 2022 12:00:00 +0000

A decent developer trick is to ensure your maven points to the right JAVA version, and if you have freshly installed maven it will be pointing to the default available.

Zookeeper mTLS

Fri, 07 Oct 2022 12:00:00 +0000

A bad way to spend one’s Friday, but at least I am ending it on a good note. — ~ Friday guru

I was struggling with the mTLS configuration for zookeeper configuration and somehow no matter what I do I kept getting an error as below

Hashicorp vault

Tue, 13 Sep 2022 00:00:00 +0000

“HashiCorp Vault is an identity-based secrets and encryption management system.”

Static IP’s in QEMU VM’s

Thu, 25 Aug 2022 12:00:00 +0000

Continuing from where I left in the blog before. If you are using looking to configure a static IP for your machines (may be your use case is similar to mine) this blog might be useful for you.

Running QEMu based VM’s on OSX M1

Wed, 24 Aug 2022 12:00:00 +0000

A popular choice in the OSS QEMu is an open source machine emulator (system emulation/usermode emulation) and virtualizer. Since I recently moved to Apple M1 silicone, I had not option of sticking to VirtualBox and was forced to relook at my options.

Vagrant-OSX

Fri, 19 Aug 2022 12:00:00 +0000

In the previous blog, I was left with the error that had little information for me to debug. I realized since I migrated most of the files from my previous laptop it might be causing an issue.

Vagrant OSX

Thu, 18 Aug 2022 12:00:00 +0000

Having just bought an M1 – MacBook Pro the issue are mounting. The premier challenge was to get my Vagrant boxes configured with provider virtualbox to run.

Since VirtualBox clearly calls it out “no support”

Weekend

Thu, 11 Aug 2022 12:00:00 +0000

G-Power

Thu, 04 Aug 2022 12:00:00 +0000

Gradle

Tue, 19 Jul 2022 00:00:00 +0000

Open source build automation tool
FLEXIBLE and builds any type of software
Run on JVM and must have a JDK installed to use it.
Gradle models its buils as DAGs pf tasks.
Build is graph of tasks
Tasks consists of
- Actions
- Inputs
- Outputs
Lifecycle Tasks
- Clean
- Check
- Assemble
- Build
- Build Configuration
- Clean Task
Gradle evaluates and executes build scripts in three phases
- Initialization
- Configuration
- Execution

Naming Convention Policy for Kafka topics

Wed, 13 Jul 2022 12:00:00 +0000

Creating a Topic in a kafka-cluster is easy and well documented for the kafka-topics.sh or even the official API documentation.

 bin/kafka-topics.sh --help

The complexity arises, when you are trying to enforce a standard way of defining topic naming. There are many ways to identify the right convention based on your need, but to enforce such a topic convention while you are creating one is explained in this 5 steps blog.

Go Modules

Thu, 07 Jul 2022 12:00:00 +0000

If you are like me and getting errors while trying to compile your go lang code without having a go.mod in v1.18

package src is not in GOROOT (/usr/local/Cellar/go/1.18.3/libexec/src/src)

Remember you have overlooked a basic change that happened post 1.16

Ansible: On Windows 10 Pro

Thu, 12 May 2022 00:00:00 +0000

Life is bringing it own challenges as I have moved to the United States of America. One of the immediate tech challenge has been using the loaner windows box and still be productive.

JMX: Monitoring and Managing Kafka

Fri, 22 Apr 2022 12:00:00 +0000

💬 The Java virtual machine (Java VM) has built-in instrumentation that enables you to monitor and manage it using the Java Management Extensions (JMX) technology.

To enable and configure monitoring of Java VM for any java-application using the ready-to-use JMX agent, you must set certain system properties when you start the Java VM.

Renewing a driver license

Mon, 04 Apr 2022 12:00:00 +0000

I never thought the process could be this simple in the year 2022. Thanks to Mr. Gadkari for taking the initiative that the states (some) have already implemented.

It starts of by signing on the portal – https://sarathi.parivahan.gov.in/sarathiservice/stateSelection.do

Ansible: Notes

Fri, 04 Mar 2022 12:00:00 +0000

Official documentation notes (Self Read)

 Getting Started
 </span>
 </button><button
 class="tab__button px-3 py-2 text-sm font-semibold border-b-2 border-transparent rounded-t-md hover:bg-neutral-200 dark:hover:bg-neutral-700 "
 role="tab"
 aria-selected="false"
 data-tab-index="1"
 data-tab-label="Playbooks">
 <span class="flex items-center gap-1">
 
 Playbooks
 </span>
 </button><button
 class="tab__button px-3 py-2 text-sm font-semibold border-b-2 border-transparent rounded-t-md hover:bg-neutral-200 dark:hover:bg-neutral-700 "
 role="tab"
 aria-selected="false"
 data-tab-index="2"
 data-tab-label="Control Node">
 <span class="flex items-center gap-1">
 
 Control Node
 </span>
 </button><button
 class="tab__button px-3 py-2 text-sm font-semibold border-b-2 border-transparent rounded-t-md hover:bg-neutral-200 dark:hover:bg-neutral-700 "
 role="tab"
 aria-selected="false"
 data-tab-index="3"
 data-tab-label="Managed Node">
 <span class="flex items-center gap-1">
 
 Managed Node
 </span>
 </button><button
 class="tab__button px-3 py-2 text-sm font-semibold border-b-2 border-transparent rounded-t-md hover:bg-neutral-200 dark:hover:bg-neutral-700 "
 role="tab"
 aria-selected="false"
 data-tab-index="4"
 data-tab-label="Inventory">
 <span class="flex items-center gap-1">
 
 Inventory
 </span>
 </button><button
 class="tab__button px-3 py-2 text-sm font-semibold border-b-2 border-transparent rounded-t-md hover:bg-neutral-200 dark:hover:bg-neutral-700 "
 role="tab"
 aria-selected="false"
 data-tab-index="5"
 data-tab-label="Modules">
 <span class="flex items-center gap-1">
 
 Modules
 </span>
 </button><button
 class="tab__button px-3 py-2 text-sm font-semibold border-b-2 border-transparent rounded-t-md hover:bg-neutral-200 dark:hover:bg-neutral-700 "
 role="tab"
 aria-selected="false"
 data-tab-index="6"
 data-tab-label="Tasks">
 <span class="flex items-center gap-1">
 
 Tasks
 </span>
 </button></div>

Control node
Managed nodes
Inventory
Modules
Tasks
Playbooks

Building blocks for Ansible.

 </div><div class="tab__panel " data-tab-index="1">
 <div class="lead text-neutral-500 dark:text-neutral-400 !mb-9 text-xl">

A playbook is composed of one or more ‘plays’ in an ordered list. — Official documentation

Ordered lists of tasks, saved so you can run those tasks in that order repeatedly.
Expressed in YAML format
It offers a multi-machine configuration & deployment system for complex applications that is
- Repeatable
- Re-usable &
- Simple

Controller machine

Has the Ansible executable installed (+Python)

 </div><div class="tab__panel " data-tab-index="3">
 <ul>

List of nodes/hosts that will be managed by control node

 </div><div class="tab__panel " data-tab-index="4">
 <ul>

List of nodes

Can specify information like IP address for each managed node.

An inventory can also organise managed nodes in groups e.g. [webserver]

 </div><div class="tab__panel " data-tab-index="5">
 <ul>

The units of code Ansible executes.

 </div><div class="tab__panel " data-tab-index="6">
 The units of action in Ansible
 </div></div>

Marathon

Fri, 04 Mar 2022 12:00:00 +0000

Bash: Named Reference

Wed, 02 Mar 2022 12:00:00 +0000

Bash is different world. Powerful, simple, elegant and complex all at the same time. Recently while trying to reduce the burden of repetitive code, I was trying to check what can be done to use references in Bash (something like pointers) and it was an interesting problem that I enjoyed solving.

SSH Protocol

Fri, 25 Feb 2022 12:00:00 +0000

💬 What is SSH protocol?

💬 It is also referred to as Secure Shell, is a method for secure remote login from one computer to another. It is an alternative to telnet and rlogin

ssh-keygen & ssh-copy-id

Fri, 25 Feb 2022 12:00:00 +0000

ssh-keygen allows generation of new key pair for authentication (SSH).

> ssh-keygen --help
unknown option -- -
usage: ssh-keygen [-q] [-b bits] [-t dsa | ecdsa | ed25519 | rsa | rsa1]
 [-N new_passphrase] [-C comment] [-f output_keyfile]
 ssh-keygen -p [-P old_passphrase] [-N new_passphrase] [-f keyfile]
 ssh-keygen -i [-m key_format] [-f input_keyfile]
 ssh-keygen -e [-m key_format] [-f input_keyfile]
 ssh-keygen -y [-f input_keyfile]
 ssh-keygen -c [-P passphrase] [-C comment] [-f keyfile]
 ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile]
 ssh-keygen -B [-f input_keyfile]
 ssh-keygen -D pkcs11
 ssh-keygen -F hostname [-f known_hosts_file] [-l]
 ssh-keygen -H [-f known_hosts_file]
 ssh-keygen -R hostname [-f known_hosts_file]
 ssh-keygen -r hostname [-f input_keyfile] [-g]
 ssh-keygen -G output_file [-v] [-b bits] [-M memory] [-S start_point]
 ssh-keygen -T output_file -f input_file [-v] [-a rounds] [-J num_lines]
 [-j start_line] [-K checkpt] [-W generator]
 ssh-keygen -s ca_key -I certificate_identity [-h] [-n principals]
 [-O option] [-V validity_interval] [-z serial_number] file ...
 ssh-keygen -L [-f input_keyfile]
 ssh-keygen -A
 ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number]
 file ...
 ssh-keygen -Q -f krl_file file ...

ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:KjqBCXEEFIBOOPDJ6j45tOBogwggxw3pAqECLG/r9fI root@mymachine.net
The key's randomart image is:
+---[RSA 2048]----+
|%* . |
|%==. |
|O*+o |
|*o* . |
|=* . S |
|*.o . . |
|Oooo... |
|=Oo.... |
|..=. oE |
+----[SHA256]-----+

SSH Keys

Notes: For self

Wed, 23 Feb 2022 07:27:42 +0000

Bash is a string oriented language
We do not write step=$((step++)) this expression will return a numeric value which the shell will then take as the command to to be executed.
No spaces are allowed around the equal sign for variable assignment.
let "step++" is same as (( step++ ))
Use declare to set variable values and attributes

In bash = and == both mean the same thing

💬 What is the difference between [ and [[?

•
if cd $dir; then
In this case the command cd $dir will be executed and based on success or failure of the command executed the if or else part will be executed respectively.
if [$dir]; then
```
<span
 class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none">
 <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#if-dir-then" aria-label="Anchor">#</a>
</span>
```
Single bracket is equivalent to test command evaluate conditional expression
1. •
  < & >
  - Within [ compare using simple ASCII ordering & within [[ comparison is lexicographic.
  - Within [ you have to escape \> to avoid redirection.

💬 BC is a language?

 <span></span>
</span>
<span class="accordion-chevron ms-auto flex h-5 w-5 items-center justify-center print:hidden">
 <span class="relative block icon"><svg

xmlns=“http://www.w3.org/2000/svg" viewBox=“0 0 20 20” fill=“currentColor” aria-hidden=“true”

💬 Supports arbitrary precision numbers with interactive execution of statements. (Command line)

awk provides filtering capabilities

> printf 'gate\napple\nwhat\nkite\n' | awk '/at/'

gate
what

printf 'gate\napple\nwhat\nkite\n' | awk '!/e/'

what

awk is primarily used for field based processing

One liner structure awk 'cond1{action1} cond2{action2} … condN{actionN}'

ServiceAccount

Wed, 16 Feb 2022 12:00:00 +0000

If you have seen errors like these when deploying using a serviceAccount

Error: INSTALLATION FAILED: rendered manifests contain a resource that already exists. Unable to continue with install: could not get information about the resource ConfigMap "spinnaker-hellow-pipline" in namespace "spinnaker": configmaps "spinnaker-hellow-pipline" is forbidden: User "system:serviceaccount:jenkins:default" cannot get resource "configmaps" in API group "" in the namespace "spinnaker"

What?
#

A service account provides an identity for processes that run in a Pod.
Every namespace has a default service account
When you create a pod, if you do not specify a service account, it is automatically assigned the default service account in the same namespace.
To use a non-default service account, set the spec.serviceAccountName field of a pod to the name of the service account you wish to use.
The service account has to exist at the time the pod is created, or it will be rejected.
The service account of an already created pod cannot be updated

Default RBAC policies grant scoped permissions to control-plane components, nodes, and controllers, but grant no permissions to service accounts outside the kube-system namespace (beyond discovery permissions given to all authenticated users). — Official documentation

Example
#

apiVersion: v1
kind: ServiceAccount
metadata:
 creationTimestamp: "2021-08-27T07:52:20Z"
 name: default
 namespace: default
 resourceVersion: "XXXX"
 uid: XXXX
secrets:
- name: default-token-vcb75

Let’s add docker-registry secret to the SA. (My secret name is samarthya-docker)

`Devspace`: Managing Apps in Kubernetes

Tue, 15 Feb 2022 12:00:00 +0000

What is `devspace`?
#

devspace is a CLI tool for kubernetes, which can help you configure, deploy, debug. and test your application inside Kubernetes.

Kaniko: Jenkins Pipeline

Fri, 11 Feb 2022 12:00:00 +0000

So there are many things I have been simultaneously trying to learn & one of those is to learn how you can configure a pipeline

Objectives
#

Learn Jenkins deployment on Kubernetes
Learn Jenkins Kubernetes Plugin
Learn Jenkins Pipeline (Declarative)
How to build and deploy images in Kubernetes cluster

All right, with so many monkeys on my back I had to do things the way I know it works for me.

Kafka: Deploy & Test

Fri, 11 Feb 2022 08:17:19 +0000

While I continue to learn more about architecture and design of kafka, a quickstart to deploy & test kafka is a must.

Step 1: Add Chart Repo
#

In my local system it is already present which was confirmed by the listing

Cert-Manager: TLS for ingress

Wed, 09 Feb 2022 12:00:00 +0000

A common use-case for cert-manager is requesting TLS signed certificates to secure your ingress resources.

cert-manager adds certificates and certificate issuers as resource types in Kubernetes clusters, and simplifies the process of obtaining, renewing and using those certificates.

Installation
#

The easiest way is to use helm charts.

IaC: Infrastructure as Code

Tue, 08 Feb 2022 12:00:00 +0000

IaC tools like Terraform allows one to manage infrastructure with configuration files rather than through a graphical user interface.

From the official website of Terraform

Installation
#

I will cover steps to install on MAC OS using brew.

Spinnaker: Artifact Helm

Sat, 05 Feb 2022 12:00:00 +0000

In this blog let’s try add a helm account and enable for use in the pipelines

bash-5.0$ hal config artifact helm account get dev-helm-ac
+ Get current deployment
 Success
+ Get dev-helm-ac artifact account
 Success
+ Artifact account dev-helm-ac: 
HelmArtifactAccount(name=dev-helm-ac, repository=https://helm-dev-local.artifactory.net/artifactory/helm-dev-local, username=myaccount, password=samplepassword, usernamePasswordFile=/home/spinnaker/.hal/helm_password)

The steps I followed are explained in detail here.

Spinnaker: Open Source Deployment

Sat, 05 Feb 2022 12:00:00 +0000

I have written a series of blogs to capture how you can deploy spinnaker on a Kubernetes cluster & manage a helm chart deployment via pipeline.

The only way to enable more frequent changes is to invest in supporting people with better tooling, practices, and culture

From the Book Spinnaker

Spinnaker: docker-registry

Fri, 04 Feb 2022 12:00:00 +0000

You will need a valid docker registry before you add any trigger in the pipeline in Spinnaker

Official documentation is a good resource to seek more clarifications — Spinnaker

In my case I have already added an account my-docker-registry as under (The final result after you successfully configure Docker.

Jenkins: K8S

Wed, 02 Feb 2022 12:00:00 +0000

Deploying Jenkins on K8S cluster is as simple as

Add Repo
#

helm repo add jenkins https://charts.jenkins.io
helm repo update

Deploy instance

Spinnaker: Install & Configure

Mon, 31 Jan 2022 06:45:59 +0000

Spinnaker is an open-source continuous delivery platform which provides two core set of features

Application Management
Application deployment

Applications , clusters , and server groups are the key concepts Spinnaker uses to describe your services.

Key Concepts
#

Some of the key concepts in the spinnaker universe are covered as under

Event Streaming

Thu, 20 Jan 2022 08:06:56 +0000

While reading Apache Kafka it was interesting analogy that they described

Event streaming is the digital equivalent of the human body’s central nervous system. — Apache Kafka

It draws a great parallel between how the central nervous system allows for real time event generations and consumption in terms of reflex actions. The examples are well explained and captured here.

Museum & Infantry

Fri, 07 Jan 2022 05:45:49 +0000

Adding Node to a cluster

Thu, 06 Jan 2022 06:58:31 +0000

In this blog, I will try add a new node to the already running cluster.

My Cluster
#

root@master>k get nodes
NAME STATUS ROLES AGE VERSION
mydevmachine001830.samarthya.me Ready <none> 22h v1.23.1
mydevmachine002687.samarthya.me Ready <none> 41d v1.23.1
mydevmachine003277.samarthya.me Ready <none> 131d v1.23.1
mydevmachine003278.samarthya.me Ready <none> 131d v1.23.1
mydevmachine003417.samarthya.me Ready <none> 4m55s v1.23.1
mydevmachine003968.samarthya.me Ready <none> 131d v1.23.1
mydevmachine003969.samarthya.me Ready control-plane,master 131d v1.23.1
mydevmachine003970.samarthya.me Ready <none> 131d v1.23.1
mydevmachine003979.samarthya.me Ready <none> 29m v1.23.1

Steps to follow
#

Install docker
Install kubeadm, kubectl & kubelet
Join the cluster using the token
Check the node has joined the cluster

Step 1: Install docker
#

sudo yum install -y yum-utils
sudo yum-config-manager \
 --add-repo \
 https://download.docker.com/linux/centos/docker-ce.repo

When adding repo make sure the repo has been added successfully to the machine

The inevitable

Thu, 06 Jan 2022 00:00:00 +0000

India is a complex country, the diversity is ever present and ever growing. What got me going in my deep meditative thinking is having a discussion with my Dad. We have evolved from the just enough generation to over the edge generation. Things that were uncommon during my growing up years and now the basic necessity of this generation.

Upgrading K8S cluster

Wed, 05 Jan 2022 07:05:30 +0000

In this blog I will talk about how you can upgrade a node and the kubernetes cluster version to a specific version.

I have a 6 node local Kubernetes cluster like below

Documenting GO

Tue, 28 Dec 2021 00:00:00 +0000

Documentation is a huge part of writing any software. In java you have JavaDoc, which most of the developers adhere to. It is healthy and rich way of exposing the source documentation.

Docker: Clean in Bulk

Mon, 27 Dec 2021 12:00:00 +0000

I will define the problem I was facing

Too many snapshots versions for the same image were there on my system

Freaky developer

So to delete there was one hard hack way of cleaning it all

K8S RBAC

Mon, 13 Dec 2021 13:03:56 +0000

What?
#

Role Based Access Control(s) is a way of regulating access to entities like storage, network etc.
RBAC authorization uses rbac.authorization.k8s.io API group.

API Objects
#

There are 4 kind of kubernetes object

Slide show

Sun, 12 Dec 2021 07:34:13 +0000

[URIS id=1836]

Just on the sides

Thu, 09 Dec 2021 07:05:51 +0000

SCM for git clone

Wed, 08 Dec 2021 09:55:42 +0000

Having used SCM plugins for quite sometime, I thought - WHY I have never used them to clone a repository and while I employ the personal access token (NOW)- The weapon of choice, I have never tried it myself.

Helm Test

Fri, 26 Nov 2021 06:07:36 +0000

The only advice I can give to folks who are building helm charts from scratch, is always keep it incremental and do not try to do everything at one go. At least build a decent few before you even try to attempt such a thing, else you will only end up WASTING your precious time on trivial issues which could have been avoided by incremental build, rather than the big bang approach.

Zabbix Agent

Wed, 10 Nov 2021 06:06:09 +0000

In this blog I will walk you through basic steps needed to deploy a Zabbix 5 Agent on a Centos Machine. The Zabbix Release is available here.

Machine
#

root@node4>cat /etc/redhat-release 
CentOS Linux release 7.9.2009 (Core)

Download and install the RPM

Happy Diwali

Sat, 06 Nov 2021 10:50:32 +0000

[video unavailable: Diwali.mp4]

CALICO CNI failures

Thu, 28 Oct 2021 07:46:58 +0000

In my cluster things went haywire all of a sudden without a proper showcase, I tried multiple things but it was just not working. Specifically my core-dns and calico-kube-controllers were not coming up and were constantly showing not ready and CrashLoop respectively

Personal Access Token

Thu, 23 Sep 2021 16:45:26 +0000

In case you are still using the basic/auth it is time to move to personal access token.

Official documentation is the best guide.

Personal access tokens (PATs) are an alternative to using passwords for authentication to GitHub Enterprise Server when using the GitHub API or the command line.

Building your artifact(s)

Thu, 23 Sep 2021 15:43:51 +0000

Everything starts form a single source file and as the time goes by, it gradually transforms into multiple modules, bulky source files and a source control repository. Mostly by this time the team has already adopted a a build tool, and a repository to publish the versioned artifacts. Journey is similar for every project successful or not.

Maven Profiles

Thu, 09 Sep 2021 08:43:10 +0000

The concept of profiles let’s a developer define what he wants to build and what to do in specific cases. In this blog I will talk about the problem that I solved using profiles.

Ingress

Tue, 24 Aug 2021 07:28:45 +0000

All right, it has been sometime since I last wrote my blog, and it has been disappointing not to have found enough time to collate and put my thoughts in a simple worded doc; better late then never. So, here I am trying to reignite the pursuit of writing at least once a week.

Om

Wed, 21 Jul 2021 10:59:57 +0000

योगस्थः कुरु कर्माणि सङ्गं त्यक्त्वा धनञ्जय ।

JUNIT5: Learning how to write the code the right way!

Sat, 05 Jun 2021 11:31:24 +0000

JUnit was developed by Kent Beck and Erich Gamma. Its first version was released in 1997.

JUnit 5 = JUnit Platform + JUnit Jupiter + JUnit Vintage — https://junit.org/junit5/docs/current/user-guide/

It is powerful testing framework, with many modules. These modules are part of three sub-projects

Cracking CISM

Tue, 25 May 2021 09:26:50 +0000

I recently gave CISM and I believe it is easily crackable. For those who are pursuing this certification the mantra is similar (or at least the one that I followed)

ISG: Information security governance

Thu, 20 May 2021 12:00:00 +0000

Rules that run the organisation = Governance. ISG includes the element required to provide the Senior Management assurance that its direction and intent are reflected in the security posture of the organisation.

Java Stream: Examples

Mon, 26 Apr 2021 09:07:19 +0000

Streams are convenient way to reduce the line of codes, but an understanding them is equally challenging. I write this blog, after realising a desperate attempt at solving a trivial problem just took overwhelming time. (Could be that I am getting old, but never late to learn things again)

Smallest Integer

Sat, 24 Apr 2021 05:43:46 +0000

Code available here.

The ask was to identify the smallest possible integer (> 0) in the array of integers.

Example
#

[-1,2] -> 1
[-1,-2] -> 1
[1,3] -> 2

I was initially thinking of using sets and then finding out the missing one, but then reaized it is simpler and I do not need sets

ReactJS: A new app `tns`

Mon, 19 Apr 2021 10:56:58 +0000

I need to write an app for a friend and what better way to brush up old concepts and write a fresh blog in doing so. So here I am, trying to put together some old and new skills together to help create a simple webapp that will have a dashboard and basic login enabled.

Secrets

Mon, 12 Apr 2021 09:35:03 +0000

To manage sensitive information you create secrets

k create secret --help

Create a secret using specified subcommand.

Available Commands:
 docker-registry Create a secret for use with a Docker registry
 generic Create a secret from a local file, directory or literal value
 tls Create a TLS secret

Usage:
 kubectl create secret [flags] [options]

Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).

type specifies the type of secret you are creating (options are as shown above). As I need to create only key value pairs for my dummy secret file I need to know a way of how to facilitate that, and the option -h helped me there

ClusterRole: Refresher

Tue, 06 Apr 2021 11:26:35 +0000

In this blog I will use kubectl to create a ClusterRole and a ClusterRoleBinding (refer to link)

{
 "kind": "ClusterRole",
 "apiVersion": "rbac.authorization.k8s.io/v1",
 "metadata": {
 "name": "myclusterrole",
 "creationTimestamp": null
 },
 "rules": [
 {
 "verbs": [
 "get",
 "list",
 "watch"
 ],
 "apiGroups": [
 ""
 ],
 "resources": [
 "persistentvolumes"
 ]
 }
 ]
}

k create clusterrole myclusterrole --verb=get,list,watch --resource=persistentvolumes

k describe clusterrole myclusterrole

You can use a ClusterRole to

define permissions on namespaced resources and be granted within individual namespace(s)
define permissions on namespaced resources and be granted across all namespaces
define permissions on cluster-scoped resources

Quotes

Sun, 04 Apr 2021 07:51:52 +0000

“There are a thousands excuses for failure but never a good reason..”

— Mark Twain

“Losers make excuses, winners make progress.”

— Introduction: The Miracle of self discipline.

oAuth: 2.0

Thu, 25 Mar 2021 15:52:46 +0000

What is OAuth?
#

From the official definition

It is protocol for Authorization

It allows authorization flows for web applications, desktop applications, mobile apps etc.

Security Standards, Baselines and Guidelines: Formalized security policy structure.

Mon, 08 Mar 2021 08:58:48 +0000

#

Standards
#

Standards are tactical documents that define steps or methods to accomplish the goals and overall direction defined by the security policies.

CISSP: Next target

Sat, 06 Mar 2021 18:08:34 +0000

I just finished my upgrade to Safe Certification and now will be going for CISSP certification. Wish my luck guys!

Some quotes
#

Effective security plans anticipates change, focuses on specific and achievable objectives, potential problems, and serves as the basis of decision making.
Operational plans are the shortest and most frequently updated
Tactical plans are mid term plans and supports strategical plans.
Strategic plans are the long term plans (usually 5 years) and usually includes risk assessment.
Data classification is the primary means by which data is protected based on its need for secrecy, sensitivity and confidentiality.
Data classification is the process of organizing objects, subjects, items into groups of similarities (value, cost, vulnerability, risk, power, privilege)
Stratify the process of organizing and securing data based on assigned labels of importance and sensitivity.
Data classification also addresses how data is removed and destroyed.
Security policy is used to assign responsibilities, define acceptable risks, define roles, specify audit requirements and indicate compliance.
Security policy are not optional rather mandatory.
Three types of security policies are regulatory, advisory and informative.

Identity

Fri, 05 Mar 2021 08:51:56 +0000

What is an identity?
#

Identity is the link that correlates the subject and the authentication process. Without a valid identity the system has no way of establishing who the subject is? Identity enables the subject to be identified and validated, and only once it has been established and authorized it is accountable for any actions taken in the system.

SAFe for Lean enterprises

Mon, 01 Mar 2021 16:14:46 +0000

SAFe is a framework; one of the leading, for business agility that allows an organization to adapt based on its own business needs. It mixes the best of Agile, Lean, DevOps into an exhaustive system of guidelines to deliver quality, innovative products in a more predictive manner.

Fun with `goroutines`

Fri, 26 Feb 2021 08:36:20 +0000

Channels are way of communication between multiple goroutines

You can declare a channel and the type of content the channel will receive like below.

var myChannel chan int

The int above is the type of data it can receive and the data can be send using

GoLang: try-catch

Mon, 22 Feb 2021 12:00:00 +0000

GoLang doesn’t have a try and catch like the popular C++ or Java languages, what it has is panic-recover.

Non critical errors are returned as normal values and for the critical ones, panic is used

VirtualBox: Increasing size of the virtual disk.

Fri, 05 Feb 2021 08:15:41 +0000

I am using Virtual Box 6.1 and will use it to expand the disk space for one my VBox Ubuntu image which was almost full.

Click on File > Virtual Media Manager

GoLang: Hash

Mon, 01 Feb 2021 09:20:50 +0000

Previously I talked about files, encoding in golang. In this LTD (learn to do) I will talk about hash package in general.

https://blog.samarthya.me/wps/2021/01/30/golang-encoding/

Help
#

Package crypto collects common cryptographic constants. — Official golang documentation

const (
 MD4 Hash = 1 + iota // import golang.org/x/crypto/md4
 MD5 // import crypto/md5
 SHA1 // import crypto/sha1
 SHA224 // import crypto/sha256
 SHA256 // import crypto/sha256
 SHA384 // import crypto/sha512
 SHA512 // import crypto/sha512
 MD5SHA1 // no implementation; MD5+SHA1 used for TLS RSA
 RIPEMD160 // import golang.org/x/crypto/ripemd160
 SHA3_224 // import golang.org/x/crypto/sha3
 SHA3_256 // import golang.org/x/crypto/sha3
 SHA3_384 // import golang.org/x/crypto/sha3
 SHA3_512 // import golang.org/x/crypto/sha3
 SHA512_224 // import crypto/sha512
 SHA512_256 // import crypto/sha512
 BLAKE2s_256 // import golang.org/x/crypto/blake2s
 BLAKE2b_256 // import golang.org/x/crypto/blake2b
 BLAKE2b_384 // import golang.org/x/crypto/blake2b
 BLAKE2b_512 // import golang.org/x/crypto/blake2b

)

Let’s try out a simple MD5 hasher.

GoLang: encoding

Sat, 30 Jan 2021 12:00:00 +0000

Package encoding provide capabilities to convert data to and from byte-level and textual representations.

encoding/gob
encoding/json, and
encoding/xml

The gob is Go’s format for serializing and deserializing. The gob was tailored for communicating between two servers written in Go.

Only exported fields are encoded; zero values are not taken into account

Package gob manages streams of gobs – binary values exchanged between an Encoder (transmitter) and a Decoder (receiver).

Format GoB
#

Let’s create a simple Type Blog and we will encode and decode it using the gob format.

GoLang: Hex Output

Fri, 29 Jan 2021 17:47:07 +0000

In last few blogs I have written about reading commandline parameters reading files and using the os package.

In this blog, I will combine some these items to read a file byte by byte using the bufio package func’s.

GoLang: Program Banner

Fri, 29 Jan 2021 07:39:04 +0000

In the last blog I talked about command line arguments os.Args[]. In this I will try and create a sample banner program that shall

Take 3 arguments
n - Number of times a message has to be repeated.
m - The message that needs to be shown.
d - If debug message needs to be shown.

I am going to use the flags package.

GoLang: Command line arguments

Wed, 27 Jan 2021 17:06:11 +0000

Reading the golang official documentation is fun, today I saw the Variables in package os

var Args []string

It allows you to hold command line arguments and a simple main program that can help you validate this.

Missed Opportunity

Mon, 25 Jan 2021 13:17:28 +0000

The new year did not begin on a note I would have expected, I missed out on a golden opportunity. It would have been a wonderful exposure had it sailed through, but as someone famously said

Files: GoLang

Mon, 25 Jan 2021 12:46:47 +0000

In the last blog, I tried reading a file in GoLang.

My repository in GitHub has all the code that I write (link)

Now, I will extend the same program to write to the same file.

Pod & Volume: K8S

Fri, 22 Jan 2021 10:19:46 +0000

Everything in the same file

apiVersion: v1
kind: Pod
metadata:
 name: redispod
spec:
 containers:
 - image: redis
 name: redisdb
 volumeMounts:
 - name: redis-data
 mountPath: /data
 ports:
 - containerPort: 6379
 protocol: TCP
 volumes:
 - name: redis-data
 persistentVolumeClaim:
 claimName: redisdb-pvc
---
apiVersion: v1
kind: PersistentVolume
metadata:
 name: redis-pv
spec:
 storageClassName: ""
 capacity:
 storage: 1Gi
 accessModes:
 - ReadWriteOnce
 hostPath:
 path: "/mnt/data"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
 name: redisdb-pvc
spec:
 storageClassName: ""
 accessModes:
 - ReadWriteOnce
 resources:
 requests:
 storage: 1Gi

If you deploy you will get something like

Files: GoLang

Thu, 21 Jan 2021 17:26:56 +0000

Learning a new syntax and the libraries is always a task, and the only way forward is gradual. In this blog I will try to create a small program to read a text file and will keep updating the program to include more sophistication

GOLang: Reflection

Sat, 16 Jan 2021 08:18:34 +0000

Must Read
#

Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types.

Reflection is a way to examine own structure. Let’s try and learn it via examples.

GOLang: Interfaces

Tue, 12 Jan 2021 09:26:04 +0000

Interfaces are an interesting concept to learn in GOLANG. There are a tonne of informative articles and here is my contribution to it.

In classical Object Oriented everything is treated in parlance of Object or Class like in Java or C++. In Go there is no class or inheritance.

Taint Nodes

Tue, 12 Jan 2021 08:57:23 +0000

Reference
#

Before we understand the tainting we should know about the Node Affinity. It the by the virtue of Affinity that pods attracts nodes as a preference or as a basic requirement.

Quick: Cheat Sheet

Fri, 08 Jan 2021 11:04:34 +0000

A cheat sheet for Installing K8S cluster.

Step1:
#

Check your OS?

cat /etc/issue
lsb_release -a

Step 2:
#

Add the GPG key as described here

DevBhoomi: Uttarkhand

Thu, 07 Jan 2021 05:48:24 +0000

Maven: Lifecycles

Thu, 24 Dec 2020 08:20:40 +0000

If you have worked with big projects you must have encountered pom.xml the central configuration for your projects that helps you build, test, and define your CI pipeline. There are other options that are available too, but that is for some other day.

K8S: Deployment

Tue, 22 Dec 2020 12:45:09 +0000

Time to re-test how to create deployments. It has been sometime, I created some deployments so just checking on how much I remember.

The quick way to always get started is to check the HELP.

Fortune v1.0

Wed, 16 Dec 2020 10:50:24 +0000

In one of recent discussions with Mr. X I was asked about my approach to solving the Linux cookie problem

A random quote
Repository will be a text file
Each quote will be segregated by a '%'
Can be multiline.

I always believe in incremental steps so here is what I could think of

Nth Prime

Tue, 15 Dec 2020 08:21:32 +0000

Prime number is an age old problem. I am trying to solve it via streams.

class PrimeCalculator {

 public int nth(int nth) {
 if (nth <= 0)
 throw new IllegalArgumentException();

 // Will skip the nth - 1
 // 2 to n-1
 return IntStream.iterate(2, i -> i + 1).filter(PrimeCalculator::isPrime).skip(nth - 1).findFirst().getAsInt();
 }

 public static boolean isPrime(int x) {
 // till half of x
 return IntStream.rangeClosed(2, (int) (x/2) ).dropWhile(i -> x % i != 0).findFirst().isEmpty();
 }
}

Explanation
#

public int nth(int nth) {
 if (nth <= 0)
 throw new IllegalArgumentException();

 // Will skip the nth - 1
 // 2 to n-1
 return IntStream.iterate(2, i -> i + 1).filter(PrimeCalculator::isPrime).skip(nth - 1).findFirst().getAsInt();
 }

The method nth(int) allows you to return the nth prime starting at 2, 3, 5....

Installing K8S on Ubuntu

Mon, 14 Dec 2020 00:00:00 +0000

Install docker

cat /etc/issue
Ubuntu 18.04.4 LTS \n \l

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
$(lsb_release -cs) \
stable"

sudo apt-get update

sudo apt-get install -y docker-ce=18.06.1~ce~3-0~ubuntu

sudo apt-mark hold docker-ce

apt-mark --help
apt 1.6.12ubuntu0.2 (amd64)
Usage: apt-mark [options] {auto|manual} pkg1 [pkg2 ...]

apt-mark is a simple command line interface for marking packages
as manually or automatically installed. It can also be used to
manipulate the dpkg(1) selection states of packages, and to list
all packages with or without a certain marking.

lsb_release -c
Codename: bionic

lsb_release -cs
bionic

systemctl status docker
● docker.service - Docker Application Container Engine
 Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
 Active: active (running) since Mon 2020-12-14 09:05:39 UTC; 45s ago
 Docs: https://docs.docker.com
 Main PID: 662 (dockerd)
 Tasks: 21
 CGroup: /system.slice/docker.service
 ├─662 /usr/bin/dockerd -H fd://
 └─685 docker-containerd --config /var/run/docker/containerd/containerd.toml

Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.297237656Z" level=info msg="ClientConn switching balancer to \"pick_first\"" module=grpc
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.297281586Z" level=info msg="pickfirstBalancer: HandleSubConnStateChange: 0xc4201b7df0, CONNECTING" module=grpc
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.297797167Z" level=info msg="pickfirstBalancer: HandleSubConnStateChange: 0xc4201b7df0, READY" module=grpc
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.297852837Z" level=info msg="Loading containers: start."
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.596242360Z" level=info msg="Default bridge (docker0) is assigned with an IP address 172.17.0.0/16. Daemon option --bip can be used to set a preferred IP addres
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.753685539Z" level=info msg="Loading containers: done."
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.822291121Z" level=info msg="Docker daemon" commit=e68fc7a graphdriver(s)=overlay2 version=18.06.1-ce
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.822430053Z" level=info msg="Daemon has completed initialization"
Dec 14 09:05:39 ip-10-0-1-101 dockerd[662]: time="2020-12-14T09:05:39.853660664Z" level=info msg="API listen on /var/run/docker.sock"
Dec 14 09:05:39 ip-10-0-1-101 systemd[1]: Started Docker Application Container Engine.

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
cat << EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF

sudo apt-get update
sudo apt-get install -y kubelet=1.14.5-00 kubeadm=1.14.5-00 kubectl=1.14.5-00
sudo apt-mark hold kubelet kubeadm kubectl

sudo kubeadm init --pod-network-cidr=10.244.0.0/16

I1214 09:10:37.236647 3055 version.go:240] remote version is much newer: v1.20.0; falling back to: stable-1.14
[init] Using Kubernetes version: v1.14.10
[preflight] Running pre-flight checks
 [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [ip-10-0-1-101 localhost] and IPs [10.0.1.101 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [ip-10-0-1-101 localhost] and IPs [10.0.1.101 127.0.0.1 ::1]
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [ip-10-0-1-101 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.0.1.101]
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 16.001809 seconds
[upload-config] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.14" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --experimental-upload-certs
[mark-control-plane] Marking the node ip-10-0-1-101 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node ip-10-0-1-101 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: xtpkvj.e81gaeg0v18shctg
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

 mkdir -p $HOME/.kube
 sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
 sudo chown $(id -u):$(id -g) $HOME/.kube/config

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
 https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 10.0.1.101:6443 --token xtpkvj.e81gaeg0v18shctg \
 --discovery-token-ca-cert-hash sha256:6c79fda4db86da060f083b35def6c39790c47f6533ab8f7ebb6ea30c2c2af6a3

Metric Server

Wed, 09 Dec 2020 08:01:49 +0000

For my local K8S cluster of 4 nodes I wanted to get the resource usage metrics. From the official documentation of kubernetes.io

These metrics can be accessed either directly by the user with the kubectl top command, or by a controller in the cluster, for example Horizontal Pod Autoscaler, to make decisions.

https://kubernetes.io

controller-manager #Unhealthy

Wed, 09 Dec 2020 07:12:34 +0000

In my K8S cluster when I was looking at component status I was observing an error.

Please note componentstatus is deprecated in 1.19+ but the steps will still at least help out the OCD’s like me.

Building a tree from Traversal.

Sun, 06 Dec 2020 10:26:53 +0000

What good is an software engineer if he can’t keep revisiting the DS problems. It is like a pill for my laziness that keeps crawling ever so often.

The problem I am talking about is mentioned in this cool portal exercism.io that I use almost on a weekly basis.

Consumer

Fri, 04 Dec 2020 14:38:51 +0000

The utility package java.util.function has this functional interface Consumer.

Each functional interface (Annotated with @FunctionalInterface) conceptually has a single method (abstract) called the functional method to which the lambda expression’s parameter and return types are matched against. Functional interfaces often represent abstract concepts like functions, actions, or predicates.

map and FlatMap

Mon, 30 Nov 2020 00:00:00 +0000

package java.util.stream;
#

Referring to the original Java 8 Documentation.

<R> Stream<R> flatMap(Function<? super T,? extends Stream<? extends R>> mapper)

Returns a stream consisting of
1. Results of replacing each element of this stream with the contents of a mapped stream produced by applying the provided mapping function to each element.

import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Main {

 public static void main(String[] args) {
	 // write your code here
 int myArray[] = { 1, 1, 2, 3, 4 , 5,6, 6,6, 7, 7, 7, 7, 7,7,3, 4, 3, 3, 2, 2, 2, 2, 2 };

 // Simple map
 // Multiply each element by 5
 Arrays.stream(myArray).map(index -> index * 5).forEach(System.out::println);
 }
}

The stream above multiplies each element by 5.

JavaStream: Characters

Fri, 13 Nov 2020 10:20:02 +0000

Continuing from the last blog how about checking a pangram using streams.

public class PangramChecker {

 private String allChars = "abcdefghijklmnopqrstuvwxyz";

 public boolean isPangram(String input) {
 if (input.length() <= 0 || input.isBlank()){
 return false;
 }
 return (allChars.chars().map(x -> (char) x).filter(x -> input.toLowerCase().indexOf(x) >= 0).count() == 26);
 }

}

All the for loops have been squeezed into a simple line

Java Streams

Thu, 12 Nov 2020 11:47:49 +0000

Stream is an new abstraction that lets one process data in a declarative way.

A stream does not store data and, in that sense, is not a data structure. It also never modifies the underlying data source.

The easiest way to learn a new API or a construct is by trying it. So here is an exercise that I tried to learn the Stream API. This is an exercise from exercism.io.

PS: Process Status

Tue, 20 Oct 2020 11:13:18 +0000

MAN Pages are one source of truth for all curious queries.

man ps

Name
 ps - report a snapshot of the current processes.

It is used to display instant information about the active processes in the system.

Kernel Mode

Sat, 17 Oct 2020 14:58:39 +0000

The CPU operates in two modes in Linux

User mode (non privileged mode)
Kernel mode (System mode)

When operating in Kernel mode it has un-restricted access to resources like memory and input output devices.

journalctl - Query the systemd journal

Sat, 17 Oct 2020 00:00:00 +0000

journald is used to query the systemd journal contents.

Example 1
#

Lets try and see the kubelet service logs in the systemd journal

Linux Utils

Tue, 13 Oct 2020 08:29:43 +0000

Ping
#

I have used ping often but never to an extend that I could understand the complete range of options and power available at hand.

Race condition

Tue, 06 Oct 2020 10:46:18 +0000

When two processes are executing concurrently, the exact order of execution of instructions is not deterministic. Without explicit synchronization instructions it is difficult to predict the outcome of these concurrent execution of process.

SYSTEMD: Mother of all processes

Wed, 30 Sep 2020 14:33:47 +0000

systemd is the replacement system for System V and with the primary goal of starting services in parallel.

Remember init levels?

GRUB: Grand Unified Boot Loader — /boot/grub/grub.conf

Some key points

Business Agility

Sun, 20 Sep 2020 10:03:52 +0000

Update
#

A dull Saturday, lazy morning and unfortunately the next door neighbor is down thanks to COVID-19. Hopefully he should recover just fine but till then we are also forced to be Home quarantined.

Writing Helm Charts

Mon, 14 Sep 2020 18:07:54 +0000

Helm is a dedicated package manager for Kubernetes.

Although the Kubernetes objects are deployed in YAML’s there was a need to package and club them together and customise the deployment (not the K8S deployment).

Helm Install

Sun, 06 Sep 2020 00:00:00 +0000

OS version

cat /etc/issue
Ubuntu 18.04.2 LTS \n \l

curl https://storage.googleapis.com/kubernetes-helm/helm-v2.12.3-linux-amd64.tar.gz > ./helm.tar.gz

Network Policy Restrictions

Fri, 04 Sep 2020 00:00:00 +0000

kubectl run --namespace=np-demo nginx --replicas=2 --image=nginx

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
 name: default-deny
 namespace: np-demo
spec:
 podSelector:
 matchLabels: {}

k expose --namespace=np-demo deployment nginx --port=80

kind: NetworkPolicy
apiVersion: networking.k8s.io/v1
metadata:
 name: access-nginx
 namespace: np-demo
spec:
 podSelector:
 matchLabels:
 run: nginx
 ingress:
 - from:
 - podSelector:
 matchLabels:
 run: allowed

k run --namespace=np-demo no-access --rm -ti --image busybox /bin/sh

wget -q --timeout=5 nginx -O -

 k run --namespace=policy-demo allowed --rm -ti --image busybox /bin/sh

Helm Charts: Packaging

Wed, 02 Sep 2020 09:12:45 +0000

Every software cycle includes packaging; which essentially describes how the software written is packaged and shared.

For the software built for Containers Helm is a popular choice of packaging the scripts.

PlayGround: K8S

Mon, 31 Aug 2020 09:39:33 +0000

I have been working on Kubernetes cluster and will soon plan to give a Kubernetes Certified Developer exam. In my quest, I will just record some commands that I found helpful or useful in this blog. It may be multi-part, as I will keep adding on a daily basis the commands that I will be learning.

MultiContainer: K8S

Thu, 27 Aug 2020 11:18:17 +0000

POD
#

Smallest deployment unit you can manage in K8S, is a Pod. A pod may have one or more containers.

Helpful links for K8S

Wed, 26 Aug 2020 09:52:02 +0000

Always remember to refer the API and elements for the YAML structure

API Overview — official K8S documentation

The Kuberenetes documentation that has text descriptions and good explanatory examples.

Deployments: K8S

Mon, 24 Aug 2020 12:29:53 +0000

A declarative way of maintaining the desired state.

Continuing my example from the last blog

--- # Pod deployment
apiVersion: apps/v1
kind: Deployment
metadata:
 name: go-server-deployment
spec:
 replicas: 2
 selector:
 matchLabels:
 app: my-go-server
 template:
 metadata:
 labels:
 app: my-go-server
 spec:
 containers:
 - name: go-server
 image: samarthya/epserver:2.0
 resources:
 limits:
 memory: "256Mi"
 cpu: "1024m"
 env:
 - name: SERVERPORT
 value: "9090"
 ports:
 - containerPort: 9090
# Reference - https://kubernetes.io/docs/concepts/workloads/controllers/deployment/

In my deployment, I have two replicas configured, which can be increased to three using the command like the one below.

NetworkPolicy: K8S

Mon, 24 Aug 2020 00:00:00 +0000

How can a pod communicate with the other pod? The answer to this question is through a network policy.

Network Policy is a specification of how groups of pods are allowed to communicate with each other and other network endpoints.

Probes: K8S

Sat, 22 Aug 2020 10:53:05 +0000

In this blog we will be talking about Liveness, Readiness and Startup probes of a container.

A Service in Kubernetes is an abstraction which defines a logical set of Pods and a policy by which to access them. — - Life without a service

What is Kubelet?
#

Kubelet is a primary node agent that runs on every node.
Works in term of PodSpec, that describes a POD (JSON or Yaml).

Liveness Probe
#

It is used by kubelet to decide when to restart the container.
periodSeconds defines when the kubelet check periodically.
initialDelaySeconds specifies the initial wait before checking.

I just created a single container pod that will run touch command to create a file and then it deletes that specific file after a delay, on which the livenessProbe is listening on and then once liveness fails we can check the container.

Services: K8S

Fri, 21 Aug 2020 17:34:29 +0000

There are multiple Kubernetes objects we will be talking about in this blog. Mainly Services, Selectors and Labels.

Service is an abstraction which defines a logical set of Pods and a policy by which to access them.
A Service in Kubernetes is a REST object, similar to a Pod.
Service tags the pods, logically grouping them using selectors.
Pods have a lifecycle, they are born, they live, process and then they die. The pods (desired state) can be managed using deployment.
A label is an identifying attribute of an object, and can be defined at the creation time, and subsequently modified and added at any time.
Label selector is a grouping primitive in Kubernetes and allows client/user to identify a set of objects. There are two sets of selectors
- equality-based and
- set-based.

An abstract way to expose an application running on a set of Pods as a network service.

The set of Pods targeted by a Service is usually determined by a selector.

ConfigMaps: K8S - 2

Fri, 21 Aug 2020 12:24:01 +0000

We looked at using the environment variables using the configmap in the last blog.

The config map remains the same but now in YAML.

apiVersion: v1
kind: ConfigMap
metadata:
 name: happy-faces-mnt
data:
 data.values: |-
 my.name=samarthya
 my.profession=engineer

I will use this to mount it to a container and then see the contents of the file.

K8S

Mon, 17 Aug 2020 07:56:44 +0000

What is K8S?
#

To manage distributed containerised workloads, you use Kubernetes.

It is resilient declarative configuration.
It is open source platform.
It allows you to bundle and run your application.

From the official Kubernetes documentation.

Kubernetes objects
#

K8S objects are the persistent entities in the K8S system and thee entities are used to represent the state of the cluster.

Dockeriz'd service

Thu, 13 Aug 2020 05:51:34 +0000

Someone asked me to define a simple docker pod for the service I wrote in GOLang here. I completely forgot about it, till today.

So here is my first attempt at getting a docker image for the service.

Performance Tweaks: Kibana

Fri, 07 Aug 2020 13:23:55 +0000

The performance I was getting after deploying Elasticsearch 7.6.2 and Kibana in my local VM’s was not satisfactory, so I thought of deploying a front proxy Nginx in front and enabling static resources caching.

Docker network

Tue, 04 Aug 2020 12:10:49 +0000

Learn by example
#

In this blog let’s learn how to create a bridge network. By definition - Bridge networks are usually used when your applications run in standalone containers that need to communicate

Timeseries & Index Management (ILM)

Sat, 01 Aug 2020 08:25:16 +0000

Timeseries is a data stream that is defined for a set of fields over a time period. Some examples may include, daily attendance register for an organization, wherein people punching in every-morning will be different, missing mostly for weekends or on planned and unplanned leaves.

Shared Volume

Fri, 31 Jul 2020 07:10:03 +0000

Volumes are managed by Docker and is the preferred way of persisting, sharing data.

Storage Drivers

Thu, 30 Jul 2020 09:28:40 +0000

The storage driver allows your to create data in the writable layers of the container and it also controls how images and containers are stored and managed on the Docker host.

Docker Registry

Wed, 29 Jul 2020 10:23:38 +0000

A Docker registry is a stateless, highly scalable server side application that stores and lets you distribute Docker images.

Docker registry is a central location that stores and distributes docker images. E.g. hub.docker.com is the default registry used when you are using docker pull.

Dockerfile

Wed, 15 Jul 2020 12:00:00 +0000

docker build builds a docker image by reading instructions (directives) from a text file called Dockerfile

The build is run by the Docker daemon, not by the CLI

Hello World!
#

I would move in stages, like a good learning guide always recommends.

PV, PVC

Wed, 15 Jul 2020 00:00:00 +0000

PV and PVC: PersistentVolume and PersistentVolumeClaim
#

PV - Defines the structure for provisioning storage for use. They have a defined lifecycle, independent of any individual Pod that uses the PV.

Docker

Sat, 11 Jul 2020 12:00:00 +0000

Usually I use Centos, but this time I wanted to try out docker swarm and ubuntu was the preferred option due to the options and supporting blogs available.

Do read – https://docs.docker.com/get-started/#containers-and-virtual-machines

docker.com

Elastic Alerting

Sun, 05 Jul 2020 00:00:00 +0000

Watcher
#

Watcher is an Elasticsearch feature that facilitates alerting and can be used to create actions based on conditions, which are periodically evaluated using queries on your data. There are two ways of creating a watcher

Devil’n the camera

Wed, 17 Jun 2020 12:00:00 +0000

A different take: SIEM

Sun, 14 Jun 2020 12:11:41 +0000

Security space is an ever evolving. It never stays stagnant; everyday you see a new exploit, a new hack. As an individual, you may have Antivirus installed on your system, Firewall - UP, ports blocked yet you are not free from threat

Aggregations: Elastic

Tue, 09 Jun 2020 00:00:00 +0000

Aggregation works on a group of documents and can be categorized

Metric
Pipeline
Bucket
Matrix

Metric Aggregation
#

Computes a single or multiple values

LDAP Realm in Elasticsearch

Fri, 05 Jun 2020 04:18:06 +0000

It is a short howto guide which shall talk about adding a LDAP realm to an Elasticsearch 7.6.2 cluster.

Realms
#

It is a concept not alien to IDAM professionals. In simple words it is a system that allows you to authenticate and authorize an incoming request. It will define the entity USER, that may include at a bare minimum (not limited to)

Elastic: Realms

Wed, 27 May 2020 00:00:00 +0000

In this blog we will try to setup a realm for elastic authentication.

yum -y install openldap-clients openldap-servers

mymachine>systemctl start slapd
mymachine>systemctl enable slapd
Created symlink from /etc/systemd/system/multi-user.target.wants/slapd.service to /usr/lib/systemd/system/slapd.service.

mymachine>slappasswd
New password: 
Re-enter new password: 
{SSHA}R5nPS+zItZsQrfsw+PIQSNnEiMpLcwLs

mymachine>vi /etc/openldap/slapd.d/cn=config/olcDatabase={2}hdb.ldif

# AUTO-GENERATED FILE - DO NOT EDIT!! Use ldapmodify.
# CRC32 975a66fa
dn: olcDatabase={2}hdb
objectClass: olcDatabaseConfig
objectClass: olcHdbConfig
olcDatabase: {2}hdb
olcDbDirectory: /var/lib/ldap
olcSuffix: dc=my-domain,dc=com
olcRootDN: cn=Manager,dc=my-domain,dc=com
olcDbIndex: objectClass eq,pres
olcDbIndex: ou,cn,mail,surname,givenname eq,pres,sub
structuralObjectClass: olcHdbConfig
entryUUID: 64a2a5de-3438-103a-8e85-c1c4cc3ef35f
creatorsName: cn=config
createTimestamp: 20200527073533Z
entryCSN: 20200527073533.541185Z#000000#000#000000
modifiersName: cn=config
modifyTimestamp: 20200527073533Z

mymachine>firewall-cmd --add-service=ldap
success

mymachine>vi ldaproot.ldif

dn: olcDatabase={0}config,cn=config
changetype: modify
add: olcRootPW
olcRootPW: {SSHA}R5nPS+zItZsQrfsw+PIQSNnEiMpLcwLs

mymachine>ldapadd -Y EXTERNAL -H ldapi:/// -f ldaproot.ldif 
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
modifying entry "olcDatabase={0}config,cn=config"

mymachine>cp /usr/share/openldap-servers/DB_CONFIG.example /var/lib/ldap/DB_CONFIG
mymachine>chown -R ldap:ldap /var/lib/ldap/DB_CONFIG
mymachine>systemctl restart slapd
mymachine>ldapadd -Y EXTERNAL -H ldapi:/// -f /etc/openldap/schema/cosine.ldif
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
adding new entry "cn=cosine,cn=schema,cn=config"

mymachine>ldapadd -Y EXTERNAL -H ldapi:/// -f /etc/openldap/schema/nis.ldif
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
adding new entry "cn=nis,cn=schema,cn=config"

mymachine>ldapadd -Y EXTERNAL -H ldapi:/// -f /etc/openldap/schema/inetorgperson.ldif
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
adding new entry "cn=inetorgperson,cn=schema,cn=config"

vi ldapdomain.ldif

dn: olcDatabase={1}monitor,cn=config
changetype: modify
replace: olcAccess
olcAccess: {0}to * by dn.base="gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth"
 read by dn.base="cn=Manager,dc=samarthya,dc=com" read by * none

dn: olcDatabase={2}hdb,cn=config
changetype: modify
replace: olcSuffix
olcSuffix: dc=samarthya,dc=com

dn: olcDatabase={2}hdb,cn=config
changetype: modify
replace: olcRootDN
olcRootDN: cn=Manager,dc=samarthya,dc=com

dn: olcDatabase={2}hdb,cn=config
changetype: modify
add: olcRootPW
olcRootPW: {SSHA}R5nPS+zItZsQrfsw+PIQSNnEiMpLcwLs

dn: olcDatabase={2}hdb,cn=config
changetype: modify
add: olcAccess
olcAccess: {0}to attrs=userPassword,shadowLastChange by
 dn="cn=Manager,dc=samarthya,dc=com" write by anonymous auth by self write by * none
olcAccess: {1}to dn.base="" by * read
olcAccess: {2}to * by dn="cn=Manager,dc=samarthya,dc=com" write by * read

mymachine>ldapmodify -Y EXTERNAL -H ldapi:/// -f ldapdomain.ldif
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
modifying entry "olcDatabase={1}monitor,cn=config"

modifying entry "olcDatabase={2}hdb,cn=config"

modifying entry "olcDatabase={2}hdb,cn=config"

modifying entry "olcDatabase={2}hdb,cn=config"

modifying entry "olcDatabase={2}hdb,cn=config"

mymachine>vi baseldapdomain.ldif

dn: dc=samarthya,dc=com
objectClass: top
objectClass: dcObject
objectclass: organization
o: samarthya com
dc: samarthya

dn: cn=Manager,dc=samarthya,dc=com
objectClass: organizationalRole
cn: Manager
description: Directory Manager

dn: ou=People,dc=samarthya,dc=com
objectClass: organizationalUnit
ou: People

dn: ou=Group,dc=samarthya,dc=com
objectClass: organizationalUnit
ou: Group

mymachine>ldapadd -x -D cn=Manager,dc=samarthya,dc=com -W -f baseldapdomain.ldif
Enter LDAP Password: 
adding new entry "dc=samarthya,dc=com"

adding new entry "cn=Manager,dc=samarthya,dc=com"

adding new entry "ou=People,dc=samarthya,dc=com"

adding new entry "ou=Group,dc=samarthya,dc=com"

dn: cn=Manager,ou=Group,dc=samarthya,dc=com
objectClass: top
objectClass: posixGroup
gidNumber: 1009

ldapadd -x -W -D "cn=Manager,dc=samarthya,dc=com" -f ldapgroup.ldif
Enter LDAP Password: 
adding new entry "cn=Manager,ou=Group,dc=samarthya,dc=com"

mymachine>useradd samarthya
mymachine>passwd samarthya
Changing password for user samarthya.

mymachine>ldapadd -x -D cn=Manager,dc=samarthya,dc=com -W -f ldauser.ldif
Enter LDAP Password: 
adding new entry "uid=samarthya,ou=People,dc=samarthya,dc=com"

dn: uid=samarthya,ou=People,dc=samarthya,dc=com
objectClass: top
objectClass: account
objectClass: posixAccount
objectClass: shadowAccount
cn: samarthya
uid: samarthya
uidNumber: 1005
gidNumber: 1005
homeDirectory: /home/samarthya
userPassword: {SSHA}R5nPS+zItZsQrfsw+PIQSNnEiMpLcwLs
loginShell: /bin/bash
gecos: samarthya
shadowLastChange: 0
shadowMax: 0
shadowWarning: 0

Installing phpLdap
#

yum install php-ldap php-mbstring php-pear php-xml

https://www.digitalocean.com/community/tutorials/how-to-install-linux-nginx-mysql-php-lemp-stack-on-centos-7

Elastic: _security API

Thu, 21 May 2020 00:00:00 +0000

Kibana is an effective way of managing users; but as a programmer you always need an API.

It helps to integrate with other applications you are building
Quick and clean way without any cosmetics

> GET /_security/_authenticate HTTP/1.1
> Host: myserver.elastic.node:9200
> Authorization: Basic ABCDEFGHIJKLMNOP==
> User-Agent: insomnia/7.1.1
> Accept: */*

< HTTP/1.1 200 OK
< content-type: application/json; charset=UTF-8
< content-length: 236

* Received 236 B chunk
* Connection #2 to host myserver.elastic.node left intact

GET https://myserver.elastic.node:9200/_security/_authenticate

I have added basic authentication to quickly check

Go: WebService [POST][GET]

Wed, 20 May 2020 08:38:20 +0000

GOLANG
#

Go is a powerful yet simple language. The nuances of assembling a workspace, sometimes are overwhelming, yet when it comes to simplicity it is very powerful.

Go: Helpful links

Tue, 19 May 2020 11:13:28 +0000

Helpful links
#

These are some of the helpful links I have used in the past for understanding Go and developing code.

WebService: In golang

Fri, 15 May 2020 11:42:46 +0000

Having practiced creating loads of Console based programs of golang, it is now time to try something new - A Web Service.

In this blog, I will try and create a Web Service (RESTful) that will be built entirely on Go.

GoLang: SmipleCipher v2.0

Tue, 12 May 2020 11:23:34 +0000

So continuing from the last blog where I wrote a crude version of SimpleCipher and was inclined on removing the duplicate code, here I am with the improved version.

Handy links
#

[fmt](https://golang.org/pkg/fmt/) package
[strings](https://golang.org/pkg/strings/) package.

Defining `types`
#

While I compiled and unit tested code the general feeling was what can be optimized.

GoLang: SimpleCipher

Mon, 11 May 2020 10:14:20 +0000

Hello back again, Golang is just a new syntax for me. Even though behind the scenes they developers have simplified many things, for a consumer like me writing a program is more about learning the new syntax and getting familiarized with the control and stack.

Analyze: _analyze api

Sat, 02 May 2020 10:21:09 +0000

Text is a key data in most of the information that is ingested in the elasticsearch, and whether it is type text or keyword it requires careful consideration to choose which analyzer to use.

Painless Scripting

Sat, 02 May 2020 00:00:00 +0000

Painless is a simple, secure scripting language designed specifically for use with Elasticsearch.

The official guide is available here.

My li'l one

Sun, 26 Apr 2020 16:09:48 +0000

[gallery columns=“1” size=“full” link=“none” ids=“617” orderby=“rand”]

Amy rose.

Sun, 26 Apr 2020 12:00:00 +0000

Index Modules

Thu, 23 Apr 2020 12:00:00 +0000

Index modules are a complex subject; they are defined per index and control every aspect of an index.

There are two types of settings for an index

Static: Can usually be defined at the creation time or when the index is closed.
- index can be closed by invoking the _close api.
- E.g. index.number_of_shards, index.shard.check_on_startup etc.
Dynamic: Can be changed on the live index using index settings api.
- E.g. index.number_of_replicas, index.refresh_interval etc.

More details available here.

Pipeline: _ingest API

Thu, 23 Apr 2020 11:08:40 +0000

Pipelines is a smooth way of processing some incoming data. In this blog, I will walk through some of the items I have tried my hands on.

Pipeline
#

A pipeline is a definition of a series of processors that are to be executed in the same order as they are declared.

_reindex, _update_by_query & _delete_by_query

Fri, 17 Apr 2020 00:00:00 +0000

_reindex
#

Official documentation here.

This API is meant for copying data from one index to another. It is especially useful when you are copying data from one index to another.

Cluster: Elastic 7.3

Tue, 14 Apr 2020 00:00:00 +0000

What is intriguing about elastic stack is that; it can do so many things that it simplifies the life of a security analyst. The uphill task is to learn the technology itself, but once you have mastered it, things are much easier.

Kuberenetes: Rest API

Wed, 08 Apr 2020 00:00:00 +0000

The Rest API is the fundamental fabric of K8S. Every communication that happens between components, happens through the API invocations.

Consequently, everything in the Kubernetes platform is treated as an API object and has a corresponding entry in the API.

Kubectl - A revisit

Tue, 07 Apr 2020 16:58:30 +0000

It is always fun learning and trying out some new tech. In this blog, I will try and capture my experience of running my first pod using kubectl.

If you wish to learn how to install a typical master, worker cluster of K8S I recommend going through this blog.

API _reindex

Mon, 06 Apr 2020 00:00:00 +0000

I will extrapolating based on the original documentation available here and based on some of my experience using this API.

It copies documents from one index to another.

Extracts the document source from the source index and indexes the documents into the destination index. You can copy all documents to the destination index, or reindex a subset of the documents.

Painless Scripting

Mon, 06 Apr 2020 00:00:00 +0000

Watcher

ECS: Elastic common schema

Thu, 02 Apr 2020 00:00:00 +0000

Open specification for document fields for data ingested in Elasticsearch. It brings uniformity to certain common fields that are used across data sources.

ECS defines two field levels

Core fields: Represent the fields that are most common across all use cases.
Extended fields: That are not part of the core and specific to cases.

Field sets
#

Field sets are multiple groups of related fields defined by ECS. More information here.

Text - Elastic

Sun, 29 Mar 2020 17:37:33 +0000

If you are not aware of mapping, it might be a little confusing but I would try my best.

Every document that gets indexed in elastic has fields, every field that is accessible has an associated type with it (Inverted Index) which helps elastic organize data for quick retrieval.

Say a Number

Sun, 29 Mar 2020 12:00:00 +0000

With the Corona-Lockdown in place “literally”, it was time to squeeze out some me-time to continue the quest for GO-Proficiency.

Sometimes you re-do optimization in your head so many times that it takes a whole day to see through the mistake you are making.

Securing Elasticsearch

Wed, 25 Mar 2020 12:00:00 +0000

In this post I will try to enable security for the elasticsearch cluster. It would be simply penned as a sequence of steps you need to follow to enable security as part of the cluster.

Snapshot & Restore

Wed, 26 Feb 2020 08:58:21 +0000

If you have a production grade elastic cluster it is always recommended to do a regular backup as a standard practice.

Snapshot is a backup of information, that can be be used to restore the last known good state of the system

Elasticsearch v7.6

Mon, 24 Feb 2020 12:00:00 +0000

In the previous blog we searched for a match_all, and sorted it by age. In this we will improve upon the query we are writing and look for other options.

Elasticsearch v7.6

Fri, 21 Feb 2020 11:24:29 +0000

What I have been doing is evaluating Elasticsearch. The indexing, searching (Phrase, Similarity, Structured, Full Text, Complex), clustering etc. In this blog I will just try and simplify the learning curve.

Package String

Sat, 15 Feb 2020 11:40:19 +0000

Just like Java or C++ there are standard libraries (packages) available with golang. The one that you might end up using the most often is strings.

For this blog, I was writing another practice exercise that is meant to count number of words in an input string.

Sieve of Eratosthenes

Thu, 13 Feb 2020 12:00:00 +0000

Sieve is an ancient and an ingenious way of calculating primes. It recursively eliminates all the multiples of a particular number up till a range and the left overs are essentially primes.

Authentication: Elastic

Thu, 13 Feb 2020 10:41:10 +0000

As a software professional, I have been working in the space of IAM, SSO, DRM for quite some time and from my experience I can say, the way Elastic has simplified the integration of external or internal security for access is a treat for fellow developers. It was interesting to experiment with the security settings, and control tenancy.

SIEM: Security Information and Event Management.

Tue, 11 Feb 2020 10:42:16 +0000

Data is key to any analytics, and if it can be organized, normalized and made available for correlated analysis, the results will be more concise. Elastic.co has a SIEM UI and the XPack security pack that helps the new age security analysts.

GOLANG: Proteins & RNA

Mon, 10 Feb 2020 15:06:21 +0000

It was an interesting exercise, and I solved in three ways. More details available here @ exercism.io

Introduction
#

RNA can be broken into three nucleotide sequences called codons, and then translated to a polypeptide like so:

सोऽहमस्मि

Mon, 10 Feb 2020 12:00:00 +0000

Life is a mystery, and autism just makes it special

soham – I am him.
#

Elastic Cluster API

Thu, 06 Feb 2020 00:00:00 +0000

Elastic Stack Monitoring Service is available with XPack only.

GET _cluster/settings

{
“persistent” : {
“xpack” : {
“monitoring” : {
“elasticsearch” : {
“collection” : {
“enabled” : “false”
}
},
“collection” : {
“enabled” : “true”
}
}
}
},
“transient” : { }
}

Pangram

Thu, 30 Jan 2020 15:59:51 +0000

I wrote my first program for Pangram in JS here and attempted few variations to optimize the readability and execution time. This time the code challenge was in Golang and it was satisfying attempt to do in first try.

Nil Interface

Sun, 26 Jan 2020 12:00:00 +0000

An interface in Golang is a set of methods and a type.

What is the purpose of Nil interface in GO-lang

A nil interface value holds neither value nor concrete type.

Metric Beat

Fri, 24 Jan 2020 12:00:00 +0000

All right, its been a busy week and finally some time at hand to write about something I have been doing.

Mostly I am working on ELK stack these days, securing, validating, data analytics etc. Today, had the opportunity to go the Secure Elastic way, by enabling the TLS for secure communication within Nodes (Elastic cluster) and finally setup a Metric beat to get the status of the node.

Securing Elastic

Thu, 23 Jan 2020 12:00:00 +0000

Security is integral to every and all the tasks in a shared environment. In ELK if you have setup a cluster which is accessible to all; anyone can make modifications which may or may not impact the other users.

Never ..be

Mon, 20 Jan 2020 12:00:00 +0000

The date was set and the time was defined, nerves were there but so were the smiles.
The pain of wrong prognosis hadn’t set in, the malevolent doc had played her game.

House that Jack built.

Fri, 17 Jan 2020 12:00:00 +0000

Funny thing about simple programs is that there are too many optimization options available that never lets you feel content.

So here I am trying to solve another problem from exercism.io which is totally a must visit for anyone who wants to learn and practice.

Security Analytics

Mon, 13 Jan 2020 00:00:00 +0000

* Header image from Elastic.co

As we move towards the micro-service/container economy where there are heaps of products available in form of applications to be downloaded & installed on primarily two platforms Android and IOS, we just cant underline the security implications enough.

Handshake: JS

Sat, 11 Jan 2020 12:00:00 +0000

Secret Handshake
#

Objective was relatively simple.

A numeral will be provided as input.
Based on the binary equivalent, one needs to compute the secret handshake.

Rule for handshake.

Maths problem in JS

Fri, 10 Jan 2020 12:00:00 +0000

Objective
#

Solve a simple math problem.

Parse and evaluate simple math word problems returning the answer as an integer.

Asynchronous

Thu, 09 Jan 2020 12:00:00 +0000

I learned a whole new dimension to this word, quite recently. Usually this word is used to express the non-blocking way of calling a program, a service or a code. Who would have thought it can be used for management or product development style as well.

Elastic 7.5

Mon, 06 Jan 2020 00:00:00 +0000

Installing
#

Step 1: Using docker
#

yum install docker
docker pull docker.elastic.co/elasticsearch/elasticsearch:7.5.1

systemctl list-units --type=service

docker version
Client:
 Version: 1.13.1
 API version: 1.26
 Package version:

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

sudo systemctl start docker

docker version
Client:
 Version: 1.13.1
 API version: 1.26
 Package version: docker-1.13.1-103.git7f2769b.el7.centos.x86_64
 Go version: go1.10.3
 Git commit: 7f2769b/1.13.1
 Built: Sun Sep 15 14:06:47 2019
 OS/Arch: linux/amd64

Server:
 Version: 1.13.1
 API version: 1.26 (minimum version 1.12)
 Package version: docker-1.13.1-103.git7f2769b.el7.centos.x86_64
 Go version: go1.10.3
 Git commit: 7f2769b/1.13.1
 Built: Sun Sep 15 14:06:47 2019
 OS/Arch: linux/amd64
 Experimental: false

docker pull docker.elastic.co/elasticsearch/elasticsearch:7.5.1
Trying to pull repository docker.elastic.co/elasticsearch/elasticsearch ... 
7.5.1: Pulling from docker.elastic.co/elasticsearch/elasticsearch
c808caf183b6: Pull complete 
05ff3f896999: Pull complete 
82fb7fb0a94e: Pull complete 
c4d0024708f4: Pull complete 
136650a16cfe: Pull complete 
968db096c092: Pull complete 
42547e91692f: Pull complete 
Digest: sha256:b0960105e830085acbb1f9c8001f58626506ce118f33816ea5d38c772bfc7e6c
Status: Downloaded newer image for docker.elastic.co/elasticsearch/elasticsearch:7.5.1

docker pull docker.elastic.co/kibana/kibana:7.5.1

Concurrency

Fri, 03 Jan 2020 12:00:00 +0000

Concurrency and Parallelism – (Helpful link)
#

Last few weeks have been interesting, a new year just embarked, my learning pace slowed down; comparatively due to the festivities and obligations around, but I am still trying to maintain.

JS Reduce and forEach

Sun, 15 Dec 2019 12:00:00 +0000

I have been polishing my Go and JS skills recently and today learned about how to use the reduce() and forEach() method. The problem I was trying to solve was return columns and rows from an input string.

Optimizing in JS

Fri, 13 Dec 2019 12:00:00 +0000

You never stop learning is not just a phrase, it is something I live everyday. Today, I was just trying out my skills with JS and was solving an innocuous problem, in JS.

MySQL/MariaDB on MAC

Fri, 01 Nov 2019 12:00:00 +0000

Challenges are plenty but outcome is always one – Learning!

While trying to troubleshoot an inhouse application I had to setup a quick MySQL instance which led me to install my first instance of MariaDB on my local MAC machine.

KubeLab

Thu, 10 Oct 2019 00:00:00 +0000

Kubernetes

cloud_user@ip-10-0-1-101:~$ kubectl version
Client Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.3", GitCommit:"721bfa751924da8d1680787490c54b9179b1fed0", GitTreeState:"clean", BuildDate:"2019-02-01T20:08:12Z", GoVersion:"go1.11.5", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.11", GitCommit:"25074a190ef2a07d8b0ed38734f2cb373edfb868", GitTreeState:"clean", BuildDate:"2019-09-18T14:34:46Z", GoVersion:"go1.11.13", Compiler:"gc", Platform:"linux/amd64"}

cloud_user@ip-10-0-1-101:~$ kubectl api-resources
NAME SHORTNAMES APIGROUP NAMESPACED KIND
bindings true Binding
componentstatuses cs false ComponentStatus
configmaps cm true ConfigMap
endpoints ep true Endpoints
events ev true Event
limitranges limits true LimitRange
namespaces ns false Namespace
nodes no false Node
persistentvolumeclaims pvc true PersistentVolumeClaim
persistentvolumes pv false PersistentVolume
pods po true Pod
podtemplates true PodTemplate
replicationcontrollers rc true ReplicationController
resourcequotas quota true ResourceQuota
secrets true Secret
serviceaccounts sa true ServiceAccount
services svc true Service
mutatingwebhookconfigurations admissionregistration.k8s.io false MutatingWebhookConfiguration
validatingwebhookconfigurations admissionregistration.k8s.io false ValidatingWebhookConfiguration
customresourcedefinitions crd,crds apiextensions.k8s.io false CustomResourceDefinition
apiservices apiregistration.k8s.io false APIService
controllerrevisions apps true ControllerRevision
daemonsets ds apps true DaemonSet
deployments deploy apps true Deployment
replicasets rs apps true ReplicaSet
statefulsets sts apps true StatefulSet
tokenreviews authentication.k8s.io false TokenReview
localsubjectaccessreviews authorization.k8s.io true LocalSubjectAccessReview
selfsubjectaccessreviews authorization.k8s.io false SelfSubjectAccessReview
selfsubjectrulesreviews authorization.k8s.io false SelfSubjectRulesReview
subjectaccessreviews authorization.k8s.io false SubjectAccessReview
horizontalpodautoscalers hpa autoscaling true HorizontalPodAutoscaler
cronjobs cj batch true CronJob
jobs batch true Job
certificatesigningrequests csr certificates.k8s.io false CertificateSigningRequest
leases coordination.k8s.io true Lease
events ev events.k8s.io true Event
daemonsets ds extensions true DaemonSet
deployments deploy extensions true Deployment
ingresses ing extensions true Ingress
networkpolicies netpol extensions true NetworkPolicy
podsecuritypolicies psp extensions false PodSecurityPolicy
replicasets rs extensions true ReplicaSet
networkpolicies netpol networking.k8s.io true NetworkPolicy
poddisruptionbudgets pdb policy true PodDisruptionBudget
podsecuritypolicies psp policy false PodSecurityPolicy
clusterrolebindings rbac.authorization.k8s.io false ClusterRoleBinding
clusterroles rbac.authorization.k8s.io false ClusterRole
rolebindings rbac.authorization.k8s.io true RoleBinding
roles rbac.authorization.k8s.io true Role
priorityclasses pc scheduling.k8s.io false PriorityClass
storageclasses sc storage.k8s.io false StorageClass
volumeattachments storage.k8s.io false VolumeAttachment

cloud_user@ip-10-0-1-101:~$ kubectl get cm
NAME DATA AGE
fruit-service-ambassador-config 1 5m49s

Basic Commands (Beginner):
 create Create a resource from a file or from stdin.
 expose Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
 run Run a particular image on the cluster
 set Set specific features on objects

Basic Commands (Intermediate):
 explain Documentation of resources
 get Display one or many resources
 edit Edit a resource on the server
 delete Delete resources by filenames, stdin, resources and names, or by resources and label selector

Deploy Commands:
 rollout Manage the rollout of a resource
 scale Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job
 autoscale Auto-scale a Deployment, ReplicaSet, or ReplicationController

Cluster Management Commands:
 certificate Modify certificate resources.
 cluster-info Display cluster info
 top Display Resource (CPU/Memory/Storage) usage.
 cordon Mark node as unschedulable
 uncordon Mark node as schedulable
 drain Drain node in preparation for maintenance
 taint Update the taints on one or more nodes

Troubleshooting and Debugging Commands:
 describe Show details of a specific resource or group of resources
 logs Print the logs for a container in a pod
 attach Attach to a running container
 exec Execute a command in a container
 port-forward Forward one or more local ports to a pod
 proxy Run a proxy to the Kubernetes API server
 cp Copy files and directories to and from containers.
 auth Inspect authorization

Advanced Commands:
 diff Diff live version against would-be applied version
 apply Apply a configuration to a resource by filename or stdin
 patch Update field(s) of a resource using strategic merge patch
 replace Replace a resource by filename or stdin
 wait Experimental: Wait for a specific condition on one or many resources.
 convert Convert config files between different API versions

Settings Commands:
 label Update the labels on a resource
 annotate Update the annotations on a resource
 completion Output shell completion code for the specified shell (bash or zsh)

Other Commands:
 api-resources Print the supported API resources on the server
 api-versions Print the supported API versions on the server, in the form of "group/version"
 config Modify kubeconfig files
 plugin Provides utilities for interacting with plugins.
 version Print the client and server version information

Usage:
 kubectl [flags] [options]

NGRX

Wed, 18 Sep 2019 12:00:00 +0000

Inspired by Redux, Store is RxJS powered state management for Angular applications. Store is a container for state of the application.

Refer to documentation at – https://ngrx.io/guide/store

Key components
#

I have a sample application posted at https://www.github.com

Security Assertion Markup Language

Tue, 17 Sep 2019 12:00:00 +0000

What is SAML?
#

Security Assertion Markup Language (SAML) is an open standard that allows identity providers (IdP) to pass authorization credentials to service providers (SP). It implements a secure method of passing user authentications and authorizations (users, logins, and attributes) between the identity provider and service providers.

Spring Data-LDAP

Wed, 24 Apr 2019 12:00:00 +0000

I have a small problem at hand which girdles around learning Angular, with a Spring enabled Rest endpoints which uses a DB to store data and have security layer in between that should interact with a LDAP for authentication and authorization and finally the application should run as one smooth unit. It will be too much to cover in single blog so I will be writing multiple blogs in continuation to this one.

Spring Data-Ldap: Part 2

Wed, 24 Apr 2019 12:00:00 +0000

Now since we have plugged in the LDAP information it is time now to stitch it with Spring Security and the easiest thing to do is

@Configuration @EnableWebSecurity(debug = true) public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

Locale

Fri, 05 Apr 2019 12:00:00 +0000

Did you ever see a warning printed on your console the moment you log into your Linux machine and did that warning ever complaned to you about the benign locale?

CSS continued

Fri, 15 Mar 2019 12:00:00 +0000

Pseudo classes
#

State dependent styling, e.g Style a checkbox when it is in checked state. It is usually denoted by a preceding colon ‘:’ (without the quote).

CSS and HTML to dom.

Fri, 08 Mar 2019 12:00:00 +0000

Happiness is not always straight lines.

Having worked on different technologies I never took HTML very seriously till a couple of years back. I started programming rather seriously programming when I was about 20 years old for a small startup then – FQSL. In those days, my primary responsibility was more around creating a middle – tier application which had a management interface and had the ability to spawn multiple threads to handle the incoming traffic and the main concern was to handle the load effectively and perform under pressure. This was all to be done in a native platform “Windows” and mostly in VC++ and MFC. Glad we are in serverless days now. 🙂

Vue - Lesson 2

Fri, 01 Mar 2019 00:00:00 +0000

Zero configuration

CLI command line interface

Create things rapidly

select libraries you want to use

Optimize the loading speed

CHoose your own adventure

Starting from a blank state

organizing the structure.

Creating your app with VUEJS

Thu, 28 Feb 2019 12:00:00 +0000

This is my attempt at learning a new framework and using it to create my own webapp uing vueJS.

Vue is a progressive and reactive framework for building user interfaces.

Learning Step - 1

Wed, 27 Feb 2019 00:00:00 +0000

The best way to learn a technology is to create something from scratch and as my ever wandering brain hops from one framework to another I am starting out on a new conquest of learning something that professionally I have never tried. Not just a scripting technology but learning the new enabler platforms as well.

Serverless patterns

Tue, 26 Feb 2019 12:00:00 +0000

Why do I need them?
#

Usually they are cost savers and beneficial for situations that are not bounded by the precise profitable point in time. What I mean to say is considering you are in to a startup and want to avoid the upfront infra cost that you may need if you want to setup a VM. You can better go for a serverless service. These services can be

How much more can you take?

Mon, 25 Feb 2019 12:00:00 +0000

Most of the times it is my wife who is diligently taking care of my little devil and sometimes I tag along. She is the one who has taken up the mettle of enduring the mud and crap the society throws at her. She is the one who has even given me courage everyday. One such face-offs she had quiet recently was when she was out with my little one, on one of the usual evening outings. My daughter is restless, full of energy and obviously autistic. Her biggest shortcoming she is unable to learn the semantics of – what you call a normal conversation.

What did the horse say?

Mon, 25 Feb 2019 12:00:00 +0000

The beauty is simplicity and nothing complex

If you ever wondered what is fun? You need to get yourself a company of a Special kid; by special I mean kids with some special needs.

Saturday morning

Sun, 24 Feb 2019 12:00:00 +0000

Morning was not early today, had a good night sleep and woke up at around 9:00 to a door bell. My devil close to my side and full of energy just stretching his tools of destruction.

Manager’s dilemma

Fri, 22 Feb 2019 12:00:00 +0000

Do not handle adults with kids gloves

Some of the gems I hear everyday and the benefits are exceptional.

You need to be direct and do not gloss the message.
You know the organization is going to back you.
The other person also gets the opportunity to demonstrate the maturity he/she possesses.

Bienvenue

Thu, 21 Feb 2019 12:00:00 +0000

This is the inspiration that drives me & my better half every day.

I don’t think the worst thing that can happen to anyone is raising a child with special needs. I think the worst thing is to raise the child who is cruel to those with special needs.

Ranjana Smarthya

Samarthya.Me: My technical journey. on Samarthya

Learning OSV, part 5: I scanned my own blog, and the real problem wasn't in the report

Learning OSV, part 4: where it fits, and my recommendation

Learning OSV, part 3: guided remediation with osv-scanner fix

Learning OSV, part 2: scanning a project with OSV-Scanner

Learning OSV, part 1: what osv.dev is and how to read a record

SSDLC when exploits are cheap: a working concept

From finding to fix: Black Duck pull requests on GitHub Enterprise Server

Why this post #

AI on this blog: a reading map

1. How machines learn #

2. How language models work #

3. Building with models #

4. Letting models act #

The data shelf #

AI in practice, part 5: MCP, the Model Context Protocol

The problem it solves #

AI in practice, part 4: From RAG to tools and agents

Three levels of “the model knows something” #

Function calling, step by step #

AI in practice, part 3: Tokens and tokenomics

What a token is #

AI in practice, part 2: ML pipelines on Google Vertex AI

Why pipelines #

AI in practice, part 1: Choosing the right framework

Reading the malware

Moving to Hugo, part 3: Living with Hugo

Writing a post #

Moving to Hugo, part 2: The migration playbook

Moving to Hugo, part 1: Why Hugo

The domain moved

Security standards, plainly, part 4: CISA KEV and BOD 26-04

Rebuilding samarthya.me, part 4: Moving the domain without losing mail

Three services, three jobs #

Rebuilding samarthya.me, part 3: A new home on Hugo

The stack #

A portal, not just a blog #

Rebuilding samarthya.me, part 2: Salvaging the content

The raw material #

Rebuilding samarthya.me, part 1: The day the blog fell

What I found #

Rebuilt on Hugo

Security standards, plainly, part 3: SLSA v1.2

Salvaging six years of posts

Security standards, plainly, part 2: OWASP SAMM v2.0

A copy of the crime scene

Security standards, plainly, part 1: NIST SSDF (SP 800-218)

The Ghost Board

MITRE ATT&CK, plainly: tactics, technique IDs and a cheat card for each tactic

OWASP Top 10:2025, plainly: the ten risks and a cheat card for each

The blog went down

The defences went off

Casino posts under my name

The password worked

Someone was knocking

The Probability engine

Know Thyself (Or At Least Try): Self-Awareness as the Foundation of Effective Leadership

Sunday Lesson

The Evolution of Language Models

A Brief History #

Language Model

Two Students, Two Talents: The Story of How AI Learns Language

Mastering TF-IDF: A Gamified Journey!

Reading Kafka JMX Data Without Getting Lost in the Numbers

k-Nearest Neighbors

Building a Practical Retrieval-Augmented Personal Assistant (RAG)

1. Why I Built This #

Data Mining Essentials

Building a Minimal LangChain + Ollama Demo

Matrix Multiplication to GPU’s

Kafka JMX: What to Enable and What It Actually Measures

The Core Divide

Beyond the `DataFrame`: How Parquet and Arrow Turbocharge PySpark 🚀

PySpark vs Pandas: Choosing Right! 🐍

Apache Spark

Quarto: A new way!

Quarto: The Future of Scientific Publishing #

CISM Notes: Connecting Technical Controls to Security Governance

Securing Kafka Brokers: A Practical Operations Checklist

Securing Kafka: Start with Identity, Transport, and Authorization

Why this post
#

1. How machines learn
#

2. How language models work
#

3. Building with models
#

4. Letting models act
#

The data shelf
#

The problem it solves
#

Three levels of “the model knows something”
#

Function calling, step by step
#

What a token is
#

Why pipelines
#

Writing a post
#

Three services, three jobs
#

The stack
#

A portal, not just a blog
#

The raw material
#

What I found
#

A Brief History
#

1. Why I Built This
#

Quarto: The Future of Scientific Publishing
#

Dialectic Inquiry: A Powerful Tool for Critical Thinking and Problem Solving
#

What is Linear Programming?
#

What is a Model?
#

Introduction
#

What is RFM Analysis?
#

Introduction
#

Introduction
#

Introduction
#

Introduction
#