Bug: Error while fetching server API version

[Goldziher]

Describe the bug

The library is raising a DockerException when trying to fetch the server version. I saw multiple older issues related to this issue, but it's now repeating.

To Reproduce

def create_container():
    container = PostgresContainer("pgvector/pgvector:pg17", driver=None)
    container.start()

Runtime environment

• M1 Pro
• Python 3.12.8
• Docker Desktop 4.37.2 (179585)
• Testcontainers 4.9.0 installed via uv

Results of running docker context ls:

NAME              DESCRIPTION                               DOCKER ENDPOINT                                          ERROR
default           Current DOCKER_HOST based configuration   unix:///var/run/docker.sock
desktop-linux *   Docker Desktop                            unix:///Users/naamanhirschfeld/.docker/run/docker.sock

[techanfa]

Same issue for
M3 chip,
Docker desktop 4.37.1
testcontainers 4.9.0 installed via poetry.
Same output from docker context ls

[alexanderankin]

My guess is that this is happening with one of the components maintained by docker, either docker desktop or the python docker client, we don't really have docker desktop in the cicd, it's not so easy to install there. I'll try to take a look if it's that, see if upgrading the python docker client helps, in case it's not the latest or something. There have been instances of python requests library causing issues as well

[Goldziher]

My guess is that this is happening with one of the components maintained by docker, either docker desktop or the python docker client, we don't really have docker desktop in the cicd, it's not so easy to install there. I'll try to take a look if it's that, see if upgrading the python docker client helps, in case it's not the latest or something. There have been instances of python requests library causing issues as well

Thank you. I reinstalled docker desktop, cleaned everything up, and restarted, and... It magically resolved.

I hate it when things are so obscure, but at least my tests are passing again.

I imagine it is something in docker desktop that is fucking things up.

Weirdly though, I was able to communicate with docker normally even when the test container library was not.

[jacobmiller22]

Same issue, had to reinstall docker desktop after macos Sequoia update.

[laurens-teirlynck]

I've also managed to fix the same issue by re-installing Docker after a Mac update. Maybe this issue can be closed since it doesn't seem to be caused by testcontainers itself.

[levrik]

I compared the locations of the .sock files of both pre-configured contexts between my system and the one of a colleague who doesn't have this issue. For him there's a symbolic link from /var/run/docker.sock (default context) to ~/.docker/run/docker.sock (linux-desktop context) which is missing from my system.

I manually created it on my machine via sudo ln -s ~/.docker/run/docker.sock /var/run/docker.sock which fixes the issue. No re-install needed.

[Goldziher]

I switched to using colima, and test-containers completely fails.

[vemonet]

@levrik solution works

There was issues with testcontainers not capable of finding the docker socket if it was not in the traditional path /var/run/docker.sock

It was recently fixed here: 6817582 it might work out of the box since this change, but it has not yet been released

[kiview]

For better triaging and debugging (for users, but also us maintainers), it seems useful to fail with a clearer error message, if there are issues when communicating (or even finding) the right Docker socket.

[peacefulseeker]

In case anyone else uses Rancher Desktop,
the symlink approach seems quickest to fix the issue raised here:
sudo ln -sf /Users/$USER/.rd/docker.sock /var/run/docker.sock

[Tranquility2]

This is likely worth re-checking now that a couple of relevant changes have landed for 4.15.0:

• feat(core): auto-detect DOCKER_HOST from current docker context #1026 makes testcontainers auto-detect DOCKER_HOST from the active docker context.
  In the original report the active context is desktop-linux (pointing at ~/.docker/run/docker.sock), so testcontainers should now use that socket automatically instead of falling back to /var/run/docker.sock, which removes the need for the ln -s workaround.
  This should also cover the Colima case from the later comment, since Colima registers its own docker context pointing at ~/.colima/default/docker.sock.
• feat(core): add Podman compatibility #1028 adds Podman compatibility, for anyone running Podman rather than Docker.

These build on the earlier rootless-socket fix (#779).

So for anyone still hitting this: could you retry on 4.15.0 (once released) and report back?
One caveat: the context auto-detection only kicks in when your active context is non-default. A misconfigured default context still relies on the rootless-socket handling from #779.