[stingraycharles]

But how would you run integration tests between multiple docker containers? We launch our services in these docker containers and do some integration / e2e tests, and this very much requires Gitlab CI to launch docker containers while inside a Docker container.

After using dind for some time we chose to just mount /var/run/docker.sock and keep using the host machine’s docker instance (mostly for the cache), but all in all dind was working fairly well.

To be honest, to say “you shouldn’t be doing that” is missing the point; one should be able to do anything they want. In my opinion, the root cause here is docker’s client/server model, which is fixed by other container runtimes such as podman and rkt (which unfortunately is deprecated). One should be able to just launch containers as if they were just another process.

[choeger]

To the contrary. You should never expect to be able to do what you want with a system provided by someone else. Gitlab has its design decisions in their default setup and you need to take control to cater your use case. This herd mentality of "everyone is doing it this way" is really fundamentally problematic.

[stingraycharles]

Nowhere in my post am I saying "everyone is doing it this way".

You started out with asserting "you're too far into Docker", we bring up valid use cases for docker-in-docker, and then you saying "This herd mentality [..] is really fundamentally problematic" is really not adding a lot to the discussion.

[choeger]

No one brought up valid use cases for docker-in-docker. They brought up the issue that gitlab mandates docker as an interface (which I totally understand, btw.).

For instance the "how do I compose multiple docker containers" is trivial when you can just execute a script that runs docker or podman. If you really want, you can use docker-compose.