Docker Swarms and Gitlab runners

Hi!

I’ve installed Gitlab CE using the guide provided at https://docs.gitlab.com/omnibus/docker/#deploy-gitlab-in-a-docker-swarm. Seems to work alright, I can create repos, users, etc. besides having to reset my password since for what ever reason it wasn’t the one I provided at the password textfile… But I’m not here about that.

The same docker-compose.yml file suggests using 4 replicas for alpine gitlab-runners. Now when I go to runners page in /admin/runners I see that there are no runners, even though docker containers ls -all does return that all 4 runner containers are running

CONTAINER ID                                                       IMAGE                                                                                                   COMMAND                                                                                             CREATED             STATUS                       PORTS                     NAMES
294946136a6b1b72563ff72a60bc185eb5ecef7a67ed53f33e32535001ce5fe1   gitlab/gitlab-ce:11.11.2-ce.0@sha256:6cf98059a1fbd5af5de46ace67069a39ba6d11128eaa0a23a5df6a10cadca316   "/assets/wrapper"                                                                                   About an hour ago   Up About an hour (healthy)   22/tcp, 80/tcp, 443/tcp   gitlab_watchtower_gitlab.1.qx5p2a5v3f7myky63kv67u3ko
f57bce4e5aa67f38e6206b94742b78b31e55ecac748704b1049704df262788de   gitlab/gitlab-runner:alpine@sha256:2f1439a8931a80f9e42a575ce1e76ed76a44c743b4b3b18f6876b4559e1dae72     "/usr/bin/dumb-init /entrypoint run --user=gitlab-runner --working-directory=/home/gitlab-runner"   About an hour ago   Up About an hour                                       gitlab_watchtower_gitlab-runner.2.grl2qliz5ew2noupmg26ppteh
25010949da64e39e49429df50ba332f42f35b3ca47e16202cfb470c2a6021602   gitlab/gitlab-runner:alpine@sha256:2f1439a8931a80f9e42a575ce1e76ed76a44c743b4b3b18f6876b4559e1dae72     "/usr/bin/dumb-init /entrypoint run --user=gitlab-runner --working-directory=/home/gitlab-runner"   About an hour ago   Up About an hour                                       gitlab_watchtower_gitlab-runner.1.878gzvunjnjn3ii3xxxco882h
7c7c18d4e2aa9c60d047c0fb28408bea4bcd615eb2ea16b323352a0229060cd7   gitlab/gitlab-runner:alpine@sha256:2f1439a8931a80f9e42a575ce1e76ed76a44c743b4b3b18f6876b4559e1dae72     "/usr/bin/dumb-init /entrypoint run --user=gitlab-runner --working-directory=/home/gitlab-runner"   About an hour ago   Up About an hour                                       gitlab_watchtower_gitlab-runner.3.9ii003d9kvbugvyd0hytnrgoz
ff807da2f8ead5876e09a299efcd7c09adccc34bf221fb99bb6f5df813460965   gitlab/gitlab-runner:alpine@sha256:2f1439a8931a80f9e42a575ce1e76ed76a44c743b4b3b18f6876b4559e1dae72     "/usr/bin/dumb-init /entrypoint run --user=gitlab-runner --working-directory=/home/gitlab-runner"   About an hour ago   Up About an hour                                       gitlab_watchtower_gitlab-runner.4.55lwspqq6ze5b2598ql2wlvnv

What else is the guide missing so that the runners would automatically authenticate to my original gitlab instance?

For reference, my docker-compose file

version: "3.6"
services:
 gitlab:
   image: gitlab/gitlab-ce:11.11.2-ce.0
   ports:
     - "23:22"
     - "80:80"
     - "443:443"
   volumes:
     - /home/ubuntu/gitlab/data:/var/opt/gitlab
     - /home/ubuntu/gitlab/logs:/var/log/gitlab
     - /home/ubuntu/gitlab/config:/etc/gitlab
   environment:
     GITLAB_OMNIBUS_CONFIG: "from_file('/omnibus_config.rb')"
   configs:
     - source: gitlab
       target: /omnibus_config.rb
   secrets:
     - gitlab_root_password
 gitlab-runner:
   image: gitlab/gitlab-runner:alpine
   deploy:
       mode: replicated
       replicas: 4
configs:
 gitlab:
   file: ./gitlab.rb
secrets:
 gitlab_root_password:
   file: ./root_password.txt

Seems to be related: https://gitlab.com/gitlab-org/gitlab-runner/issues/1285

The Gitlab documentation related to Docker Swarm is incomplete to not say wrong.
https://docs.gitlab.com/omnibus/docker/#deploy-gitlab-in-a-docker-swarm

The Gitlab team does not provide anything to help unlocking the situation. No clear communication on this. A lot of people are complaining on different posts and issues but not clear explanation? Why?!

Gitlab is a fantastic tool as a user but the Docker Swarm setup seems impossible without a lot of manual tasks or operations to automatize it. Disappointment!