I'm running a gitlab/gitlab-ce container on docker. Then , inside it, i want to run a gitlab-runner service, by providing docker as runner. And every single command that i run (e.g docker ps, docker container ..), i get this error:
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running
P.s: i've tried service docker restart, reinstal docker and gitlab-runner.
By default it is not possible to run docker-in-docker (as a security measure).
You can run your Gitlab container in privileged mode, mount the socket (-v /var/run/docker.sock://var/run/docker.sock) and try again.
Also, there is a docker-in-docker image that has been modified for docker-in-docker usage. You can read up on it here and create your own custom gitlab/gitlab-ce image.
In both cases, the end result will be the same as docker-in-docker isn't really docker-in-docker but lets your manage the hosts docker-engine from within a docker container. So just running the Gitlab-ci-runner docker image on the same host has the same result and is a lot easier.
By default the docker container running gitlab does not have access to your docker daemon on your host. The docker client uses a socket connection to communicate to the docker daemon. This socket is not available in your container.
You can use a docker volume to make the socket of your host available in the container:
docker run -v /var/run/docker.sock:/var/run/docker.sock gitlab/gitlab-ce
Afterwards you will be able to use the docker client in your container to communicate with the docker daemon on the host.
