Docker compose does not take into account .dev.env file

[NerijusNoreika]

I've setup .env.dev for custom configuration, but it seems to be ignored - only the confiuration from .env file is used.

For example, I set SERVER_NAME on .env.dev to be different from the one in .env, but docker seems to use only the value from .env.

I thought perhaps I need to explicitly define the APP_ENV environment variable:

  php:
    restart: unless-stopped
    environment:
      APP_ENV: dev

but that does not help.

However when I check with command bin/console env I see correct values, both inside the container and outside of it. So to me it seems, like the compose.yaml file just picks the value from .env and ignores all other environment files?

[7-zete-7]

Hi @NerijusNoreika!

The .env.dev, .env.prod, .env.test, and other files are used by Symfony. Docker Compose only use the .env file by default.

If you want these files to be used by Docker Compose as well, use the following command:

docker compose --env-file=.env --env-file=.env.dev ...

See docker compose options.

[NerijusNoreika]

@7-zete-7 Thanks for the clarification.

I wonder then if using fallback .env files would be an interesting improvement for docker compose files. https://docs.docker.com/compose/how-tos/environment-variables/set-environment-variables/#additional-information-1

For example for prod yaml, it could look like this:

env_file:
  - path: ./.env
    required: true
 - path: ./env.local
    required: false
   - path: ./.env.prod
    required: false
  - path: ./.env.prod.local
    required: false

The later .env files overwrite the data from previous ones. Perhaps that would make .env configuration more flexible, since we would not need to write env variables directly on docker compose command. For dev it would look similar, just that we would use .env.dev variants.

What do you think?

[7-zete-7]

@NerijusNoreika I agree with you. It would be more convenient if Docker Compose offered the ability to configure something like this. But I'm not sure it will ever be possible to do this through configuration files.

For example, I solve this problem by using a Taskfile or a Makefile. In both solutions, you can define your own logic for building the docker compose ... command.

To clarify (to avoid misleading those reading this thread): the --env-file option is not the same as the env_file attribute. The --env-file option will allow the use of envs from the specified .env file in the Docker Compose configuration file, while the env_file attribute will only forward the envs to the container. Using the env_file attribute will generally achieve the same effect as Symfony already does.