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.
# Lesson 1 - Using basic Dockerfile to compose an image
FROM alpine:3.7
# Using alpine 3.7 latest on the day.
CMD ["echo","Hello world!"]The file above uses two directives and an image
Format: directive#
Every directive you write in your docker file would follow a template
# INSTRUCTION arguments
FROM alpine:3.7FROM directive identifies the parent image
alpine#
This is a 5mb image small and convenient to get started in our case. You can find more details on how to use it here.
docker build -t samarthya/ahello:1.0 .Sending build context to Docker daemon 2.048kB
Step 1/2 : FROM alpine:3.7
---> 6d1ef012b567
Step 2/2 : CMD ["echo","Hello world!"]
---> Running in 4c96833eaeb6
Removing intermediate container 4c96833eaeb6
---> 460a990ca06c
Successfully built 460a990ca06c
Successfully tagged samarthya/ahello:1.0docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
samarthya/ahello 1.0 460a990ca06c About a minute ago 4.21MBdocker image history 460a990ca06c
IMAGE CREATED CREATED BY SIZE COMMENT
460a990ca06c About a minute ago /bin/sh -c #(nop) CMD ["echo" "Hello world!… 0B
6d1ef012b567 16 months ago /bin/sh -c #(nop) CMD ["/bin/sh"] 0B
<missing> 16 months ago /bin/sh -c #(nop) ADD file:aa17928040e31624c… 4.21MBA simple execution allows to see the desired output.
docker run --name hello samarthya/ahello:1.0
Hello world!
