Recently I noticed that my CI/CD jobs keep failing with an error
Cannot connect to the Docker daemon at tcp://localhost:2375 Is the docker daemon running?.
I’m using the Docker in Docker (DinD) workflow, and there wasn’t a change on my end. Ultimately, I spent too much time verifying that my GitLab Runner version was OK – actually, it was pretty old (11.x) so I fixed that, checked for the
--privileged flag, redid the RBAC authorization, Secrets, the Helm release, and finally, the docker client/server versions.
The solution is to specify
docker:18-dind for your services (previously:
docker:dind) so jobs don’t randomly fail when new versions of Docker are released. There’s also a post from the company about this same topic, see https://about.gitlab.com/2019/07/31/docker-in-docker-with-docker-19-dot-03/.