programming-basics-2022/10_docker/lesson06/README.md

Lesson 6: Environment variables and configuration

1. Change directory into lesson06.

2. A popular way to provide configuration information to a docker container is via environment variables.

3. Let's try it:

    $ docker build . -t demo
    $ docker run -it --rm --name fuzzle demo
   

4. Does the output make sense?

5. Let's pass in a value for the environment variable HELLO_WORLD:

    $ docker run -it --rm --name fuzzle -e HELLO_WORLD='Hello, world.' demo
   

6. You can also pass in environment variables via a file:

    $ cat file.env
    # We define two environment variables (you CAN comment!)
    HELLO_WORLD="Hello, world."
    ENV_VAR2="another environment variable"
   
    $ docker run -it --rm --name fuzzle --env-file=file.env demo
   

7. If your Docker application does not have many configuration options configuring via environment variables is a good method. However, if the application has complicated or extnesive configuration this may not be feasible.

8. Don't forget to clean up:

    $ docker rmi demo:latest (removes the image demo:latest)