docker-compose container name use dash (-) instead of underscore (_)

Question

I always used docker-compose on Ubuntu, in this environment containers are named with underscore:

• <project>_<service>_<replica>

But now, I switched to Windows 10 (using Docker Desktop) and naming convention has changed:

• <project>-<service>-<replica>

I don't know if this is OS dependent but it's a problem. My scripts are failing because they rely on containers named with underscores.

Is there a way to customize this and use underscore instead of dashes?

Answer 1

This naming convention difference appears to be a difference between Docker Compose versions v1 (Python) and v2 (Go). The latest docker/compose repo that is packaged with Docker Desktop is the golang version in the docker/compose v2 branch. Looking at the source code here in this branch:

// Separator is used for naming components
var Separator = "-"

The python branch source code is using the _ naming convention for components, here for example:

    def rename_to_tmp_name(self):
        """Rename the container to a hopefully unique temporary container name
        by prepending the short id.
        """
        if not self.name.startswith(self.short_id):
            self.client.rename(
                self.id, '{}_{}'.format(self.short_id, self.name)
            )

As to solving this, you may want to uninstall the compose included with Docker Desktop and revert to a 1.28.x version. The compose readme says you can use pip install docker-compose to install. The compose docs have a section about upgrading this and commands to migrate to v2: https://docs.docker.com/compose/install/#upgrading but your question suggests you want to stay with the _ v1 naming convention.

As mentioned in comments, the following options retain the compose compatibility:

1. use --compatibility flag with docker-compose commands
2. set COMPOSE_COMPATIBILITY=true environment variable

Other doc links:

• Backward compatibility is discussed here: https://github.com/docker/compose#about-update-and-backward-compatibility
• Docs/Readmes suggest installing compose-switch for translating docker-compose commands
• If you instead want to upgrade to v2 on Ubuntu and modify scripts: https://docs.docker.com/compose/cli-command/#install-on-linux