Allow runner server to have no internet access and communicate through private network with gitlab
Summary
On a gitlab CE installation, we configured runners on a remote server. They communicate properly and jobs are executed without problem.
But recently, we decided to remove the public internet IP of the machine where the runners are.
Both gitlab and runners servers are on the same private network. Ping works like a charm from gitlab server to runners one using internal private ip.
Communication stops as long as runners server has no more internet access.
Steps to reproduce
Register runners on a remote server, but on the same private network than Gitlab instance.
Remove public IP from runners server and internet access from the runner server.
Actual behavior
Pipelines are not executed on runners anymore. Runners and gitlab can't communicate because they try to communicate over https on public gitlab address.
Expected behavior
Pipeline should continue to execute on runners since they are still reachable by gitlab through private network.
To do so we could be able to make runners and gitlab communicate through direct private network ips communication / ssh or any other method, not requiring https over public gitlab address
Environment
No firewall running on servers. Both servers on same private network.
Ping one server ip from each other works.
Reaching internet from runner server disabled (total private Scaleway network).
Used GitLab/Gitlab Runner version
9.4
Will also post on Gitlab issues list if this can be related to gitlab side.