Digital Ocean droplet & gitlab runner problem

Question

I am recently working on GitLab CI/CD and I want to set up a runner on digital ocean droplet however I get the following error:

$ docker network create web
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
Cleaning up project directory and file based variables
00:00
ERROR: Job failed: exit code 1

how should I avoid this problem, consider that the docker is up and running on the droplet ubuntu with 8 GB ram

Answer 1

it can be only one of this reason:

a) gitlab-runner user is not in docker group

id gitlab-runner

should show something like

uid=998(gitlab-runner) gid=998(gitlab-runner) groups=998(gitlab-runner),1001(docker)

b) docker service is not running in droplet