Problems with docker concurrent builds

Hi there,

I’m using a gitlab runner using Docker in Linux (and I’ve used docker to deploy the runner itself, by mounting the docker socket into the runner, following the instructions) and I have a problem when 2 concurrent builds are using said runner. I’m getting (as an example):

Fetching changes with git depth set to 50...
 Reinitialized existing Git repository in /builds/myUsername/myProject/.git/
 fatal: shallow file has changed since we read it

…because /builds is mounted into the docker container, so changes on one of the runners are being seen by the other runner and trashing it. I expected each docker image to have its own copy of the repository and not clobber each other like that. How can I configure my runners so I don’t have this kind of problem?

Thanks in advance.

Looks like said change was done here https://gitlab.com/gitlab-org/gitlab-runner/-/issues/1520 but I have no docker “services”, I have normal jobs with a few steps, that’s it…

I’ve tried using the CI_CONCURRENT_ID and a custom clone path to workaround this issue (which in my mind should not happen. I understand that taking care of my build scripts be concurrent aware is my responsibility, but this is a problem with the clone step, which I don’t have real control over?) but $CI_CONCURRENT_ID is always 0, so nothing has really changed…

Hi @arcnor. Did you manage to find a fix for this issue? I’ve had various problems over the last day with concurrent docker builds on a runner using the Docker executor on Linux. One of the problems I’ve had is exactly what you’ve described here

My only “fix” was to remove concurrency, unfortunately. After reading many issues, I think this was by design somehow? I haven’t found the time to find a better solution, but if you find any please share, I’ve spent too much time on this already :slight_smile:.

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