Why is docker-compose downloaded when I have docker WITH compose installed already?

[func0der]

Hey,

I have been wondering since I started using ddev, why it would install docker-compose. docker-compose is basically a dead or better migrated product at this point.
It has been replaced with docker compose (v2 or whatever you may call it).

I could not find documentation, an issue or similar info about this behaviour. I only know it does download it (not even from where xD).

Can somebody please explain?

[rfay]

Hi @func0der - docker-compose is by no means a dead product. It's actually a docker plugin that can be run either as docker compose (if correctly installed in ~/.docker/cli-plugins) or as docker-compose (if in the PATH or if explicitly pathed). If you look at the project releases, you'll see they're all docker-compose. https://github.com/docker/compose/releases

DDEV has used docker-compose v2 for a number of years. We currently use v2.29.7.

DDEV downloads its own tested and verified private docker-compose so that you do not have to install one. Unfortunately, docker-compose periodically introduces new bugs and so we don't change the version on it until it has been verified. In the early days of docker-compose v2, nearly every release had a new problem. These days it's not such a serious problem, but since we can't control what people may have installed, we test each one before specifying it for use in DDEV (where the private version in ~/.ddev/bin/docker-compose is used).

We do not use any docker-compose except the private one for DDEV, and in fact no docker-compose or docker compose needs to be installed on your system to use DDEV, because DDEV downloads its own.

You can see the version in use on your DDEV installation with ddev version

If we were to use the docker plugin approach (docker compose), then everybody would have to install the same compose plugin in their ~/.docker/plugins directory, and we wouldn't be able to control the version at all. And no benefit would be derived.