Proposal: support for args_file

[mbontemps]

Motivation for this proposal

• build args have been introduced in Docker 1.9.0.

• 2163 proposes a new build: section in your Compose service

• builds args can be used to provide secret tokens (ssh key to clone a repository, github token...) during the build phase. These tokens should however not appear in your docker-compose.yml file but rather in a separate file.

  Proposal

Introduce a args_file: section working the same way that env_file: works - but in the build phase.

Proposed documentation

args_file

Add build arguments from a file. Can be a single value or a list.

If you have specified a Compose file with docker-compose -f FILE, paths in args_file are relative to the directory that file is in.

Environment variables specified in args override these values.

build:
 args_file: .args

build:
  args_file:
    - ./common.env
    - ./apps/web.env
    - /opt/secrets.env

Compose expects each line in an env file to be in VAR=VAL format. Lines beginning with # (i.e. comments) are ignored, as are blank lines.

# Set the secret token necessary to clone the dependencies
SECRET_TOKEN=yNxbjX

[aanand]

Makes sense to me.

[marcellodesales]

:+1:

[thaJeztah]

Nice idea

I'm not sure we should use /opt/secrets.env as an example in our documentation, given that we discourage people to use build-time args for secrets (the args are included in the history of an image, so would be visible to others)

[daef]

i'd really love args_file, i kinda expected it to be there - but i am disappoint now i've found it just got proposed

[marcellodesales]

@thaJeztah Is this planned for the next release?

[schmunk42]

These tokens should however not appear in your docker-compose.yml file

A workaround is to use a .env file and ENV variables (compose 1.7+ AFAIR)

version: '2'
services:
  php:
    build:
      dockerfile: Dockerfile-7.0-fpm
      context: .
      args:
        - GITHUB_API_TOKEN=${GITHUB_API_TOKEN}
    image: local/dmstr/php-yii2
    environment:
      - GITHUB_API_TOKEN=${GITHUB_API_TOKEN}

[yangm97]

@schmunk42 that workaround didn’t work for me.

[schmunk42]

@yangm97 Did you try with a recent docker-compose version? Can you set build args in docker-compose (without variables)?

[yangm97]

docker-compose version 1.9.0, build 2585387

Setting args on docker-compose.yml work fine.

  bot:
    build:
      args:
        - LUA=5.2 # this works
        - NATIVE=${NATIVE} # these don't
        - ROCKS=${ROCKS}
      context: .
    command: $BOT
    depends_on:
      - db
      - redis
    env_file:
      - .deps
      - .env
    environment:
      - NATIVE=${NATIVE}
      - ROCKS=${ROCKS}
      - REDIS_HOST=redis
      - DB_HOST=db
    privileged: true
    restart: always

[yangm97]

So far, the only ways I got to read build time arguments from a file were:

1. Source the args file on host and then run docker-compose with build args;
2. Copy the args file on the Dockerfile and then source the file using the RUN command.

[schmunk42]

These have to be in your .env file

NATIVE=${NATIVE}
ROCKS=${ROCKS}

Double check it with docker-compose config

[yangm97]

These have to be in your .env file

I have multiple env files:

    env_file:
      - .deps
      - .env

Do I need to explicitly set these variables on .env or it should work when I set these using the .deps file?

My .deps file looks like this:

LUA=5.2

NATIVE="libreadline-dev libssl-dev lua$LUA luarocks liblua$LUA-dev curl libcurl4-gnutls-dev figlet deborphan git make unzip"
ROCKS="luasec luasocket redis-lua lua-term serpent dkjson Lua-cURL lanes luautf8”

[schmunk42]

Do I need to explicitly set these variables on .env or it should work when I set these using the .deps file?

Yes, it has to be in .env - which is the default for docker-compose. I've written about this in the docs for our application framework. I won't recommend using .env as an application environment file, btw.

It's a bit confusing, because docker-compose has "hijacked" this filename, when a lot of people were already using it for applications. I'd call it "control-environment" file now.

[jvitor83]

Any ETA for that?

[stephan-henningsen]

Add the env_file already! 4 years have passed since this was first proposed here.

[ndeloof]

I think it would make perfect sense if docker build had support for some --args-file option, and then compose to align with it. As compose offers option to run the build using the plain docker CLI, transposing arg_file option to the CLI would require extra efforts and potential bugs.

[joshua-hester]

Whats the resolution on this?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[peabnuts123]

Is there a label that can be added to this to prevent it from going stale? It's a feature request.

[stale[bot]]

This issue has been automatically marked as not stale anymore due to the recent activity.

[maciekgrochowicz]

So 5.5 years after this issue was opened: any plans to actually implement that?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[daef]

⚡⚡ issue: activate! ⚡⚡

[stale[bot]]

This issue has been automatically marked as not stale anymore due to the recent activity.

[ndeloof]

As noted on https://github.com/docker/compose/issues/2545#issuecomment-543099520, this feature would only make sense if aligned with other docker commands, i.e. if docker build --args-file .. is a thing, then obviously docker compose should support this as well. For this reason, I'm closing this issue as "not planned", in a sense "not planned as a standalone docker compose feature" - if docker CLI or buildx evolves to offer this feature, we'll be happy to de the same.

[daef]

env-file is not aligned enough?