docker stack config

Swarm This command works with the Swarm orchestrator.

Description

Outputs the final Compose file, after doing the merges and interpolations of the input Compose files.

Options

Examples

The following command outputs the result of the merge and interpolation of two Compose files.

$ docker stack config --compose-file docker-compose.yml --compose-file docker-compose.prod.yml

The Compose file can also be provided as standard input with --compose-file -:

$ cat docker-compose.yml | docker stack config --compose-file -

Skipping interpolation

In some cases, it might be useful to skip interpolation of environment variables. For example, when you want to pipe the output of this command back to stack deploy.

If you have a regex for a redirect route in an environment variable for your webserver you would use two $ signs to prevent stack deploy from interpolating ${1}.

  service: webserver
  environment:
    REDIRECT_REGEX=http://host/redirect/$${1}

With interpolation, the stack config command will replace the environment variable in the Compose file with REDIRECT_REGEX=http://host/redirect/${1}, but then when piping it back to the stack deploy command it will be interpolated again and result in undefined behavior. That is why, when piping the output back to stack deploy one should always prefer the --skip-interpolation option.

$ docker stack config --compose-file web.yml --compose-file web.prod.yml --skip-interpolation | docker stack deploy --compose-file -