Accessing env variables within docker-compose.yml

[bentcoder]

Hi,

I am getting errors below when trying to run docker-compose up. The errors are related to the docker-compose.yml file not the Dockerfile though. How can I make docker-compose.yml access env variables as well?

Thanks

Versions

docker-compose version 1.17.0, build ac53b73
Docker version 17.09.0-ce, build afdb6d4

Errors

WARNING: The MY_IP variable is not set. Defaulting to a blank string.
ERROR: The Compose file 'docker-compose.yml' is invalid because:
services.php.ports is invalid: Port ranges don't match in length

variables.env

MY_IP=192.168.0.11
MY_PORT=9000

Dockerfile (vars work here)

FROM php:7.1-fpm
ENV MY_IP
ENV MY_PORT

docker-compose.yml

version: '3'
services:
    php:
        build: ./php
        ports:
            - ${MY_PORT}:80
        networks:
            public_net:
                ipv4_address: ${MY_IP}
        env_file:
            - variables.env
networks:
    public_net:
        ...

[thaJeztah]

The env_file option only sets environment-variables for the docker container that is started, but environment variable interpolation in the docker-compose file itself is done from actual environment variables set in your shell session.

For example;

export MY_IP=192.168.0.11
export MY_PORT=9000

Then running docker-compose up should work

I notice you're "baking" those values into the container's image; given that these values may change, it's probably better to set them at runtime (unless you really need them during build)

Assuming your php image does not need other build-steps than the ones you showed, you can use the upstream php:7.1-fpm image directly, and set the environment variables for the container at runtime;

version: '3'
services:
    php:
        image: php:7.1-fpm
        ports:
            - ${MY_PORT}:80
        networks:
            public_net:
                ipv4_address: ${MY_IP}
        environment:
            - MY_PORT
            - MY_IP
networks:
    public_net:

Notice that you don't add an = or =some value to the environment variables; omitting the = tells docker-compose to set those environment variables from actual environment variables on the host (if set).

If you don't want to export those environment variables before running, you can also create a .env file in the same directory as the compose-file, and docker compose will read that file when running commands (but be aware that this feature is not supported when deploying your compose file using docker stack deploy)

[docker-robott]

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