Run a GitLab Runner on your Swarm

swarm.yml

version: '3.4'

secrets:

  # Find your registration token at: "Your project" > "Settings" > "CI/CD" > "Runners settings" > "Specific Runners" (look for registration token)
  # Register it as `GITLAB_REGISTRATION_TOKEN`: `docker secret create GITLAB_REGISTRATION_TOKEN YOUR_REGISTRATION_TOKEN`
  GITLAB_REGISTRATION_TOKEN:
    external: true
  # Find your personal access token at: "Your user account" > "Settings" > "Access Tokens" > "Create personal access token" (for api)
  # Register it as `GITLAB_PERSONAL_ACCESS_TOKEN`: `docker secret create GITLAB_PERSONAL_ACCESS_TOKEN <YOUR ACCESS TOKEN>`
  GITLAB_PERSONAL_ACCESS_TOKEN:
    external: true

services:

  # Gitlab Runner - https://gitlab.com/gitlab-org/gitlab-runner
  runner:
    image: gitlab/gitlab-runner:latest
    environment:
      - CONCURRENT=8
      - REGISTER_LOCKED=1
      - REGISTER_NON_INTERACTIVE=1
      - RUNNER_EXECUTOR=docker
      - DOCKER_IMAGE=docker
      - DOCKER_VOLUMES=/var/run/docker.sock:/var/run/docker.sock
      - RUNNER_NAME=docker
      - API_URL=https://gitlab.com/api/v4
      - CI_SERVER_URL=https://gitlab.com/ci
    entrypoint: "bash"
    secrets:
      - GITLAB_REGISTRATION_TOKEN
    command: |
      -c '
        set -e

        printf "Setting configuration...\\n"
        export REGISTRATION_TOKEN="$$(cat /run/secrets/GITLAB_REGISTRATION_TOKEN)"
        sed -i "s/^concurrent = .*/concurrent = $${CONCURRENT}/" /etc/gitlab-runner/config.toml
        printf "\\n"

        printf "Registering runner...\\n"
        gitlab-runner register --non-interactive
        printf "\\n"

        printf "List runners...\\n"
        gitlab-runner list
        printf "\\n"

        printf "Running runner...\\n"
        gitlab-runner run --user=gitlab-runner --working-directory=/home/gitlab-runner --metrics-server=:9252
      '
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    deploy:
      mode: global
      placement:
        constraints:
          - node.role == manager
      labels:
        - "traefik.enable=false"
    healthcheck:
      test: ["CMD-SHELL", "gitlab-runner verify --name docker 2>&1 | grep --quiet \"is alive\""]
      start_period: 10s
      interval: 10s
      timeout: 10s
      retries: 10

  # Gitlab Manager to unregister GitLab Runners
  manager:
    image: alpine:latest
    environment:
      - API_URL=https://gitlab.com/api/v4
      - CI_SERVER_URL=https://gitlab.com/ci
    secrets:
      - GITLAB_PERSONAL_ACCESS_TOKEN
    entrypoint: sh
    command: |
      -c '
        set -e

        printf "Installing dependencies...\\n"
        apk --no-cache add curl jq
        printf "\\n"

        export PERSONAL_ACCESS_TOKEN="$$(cat /run/secrets/GITLAB_PERSONAL_ACCESS_TOKEN)"
        while true; do
          printf "Checking runners...\\n"
          curl -sS --header "PRIVATE-TOKEN: $${PERSONAL_ACCESS_TOKEN}" "$${API_URL}/runners?per_page=100" | \
          jq -c ".[] | select(false==.is_shared) | select(\"online\"==.status) | .id" | \
          while read RUNNER_ID; do
            printf "Runner $${RUNNER_ID} is online\\n"
          done
          curl -sS --header "PRIVATE-TOKEN: $${PERSONAL_ACCESS_TOKEN}" "$${API_URL}/runners?per_page=100" | \
          jq -c ".[] | select(false==.is_shared) | select(\"online\"!=.status) | .id" | \
          while read RUNNER_ID; do
            printf "Deleting runner $${RUNNER_ID}...\\n"
            curl -sS --request DELETE --header "PRIVATE-TOKEN: $${PERSONAL_ACCESS_TOKEN}" "$${API_URL}/runners/$${RUNNER_ID}"
          done
          printf "All offline runners deleted\\n"
          printf "Waiting for 24 hours...\\n"
          sleep 24h
        done
        printf "\\n"
      '
    deploy:
      labels:
        - "traefik.enable=false"
    healthcheck:
      test: ["CMD-SHELL", "command -v curl"]
      start_period: 10s
      interval: 10s
      timeout: 10s
      retries: 10

  # Gitlab Runner Docker Cleanup - https://gitlab.com/gitlab-org/gitlab-runner-docker-cleanup
  cleaner:
    image: quay.io/gitlab/gitlab-runner-docker-cleanup
    environment:
      - CHECK_PATH=/data
      - LOW_FREE_SPACE=10G
      - EXPECTED_FREE_SPACE=20G
      - LOW_FREE_FILES_COUNT=1048576
      - EXPECTED_FREE_FILES_COUNT=2097152
      - USE_DF=1
      - CHECK_INTERVAL=10s
      - RETRY_INTERVAL=30s
      - DEFAULT_TTL=60m
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /data:/data
    deploy:
      restart_policy:
        condition: any
      labels:
        - "traefik.enable=false"

I could not get it working, the runner were showing up in GitLab and also assigned to jobs but they were simply hanging, but I'll give it another try! Thanks for confirming that it's still working.

if it is not working please provide more informations and logs from container .... if it hangs without any errors in logs, it can be a network issue

Ah one thing, the api has changed a bit, you need to edit the compose from
curl -sS --header "PRIVATE-TOKEN: $${PERSONAL_ACCESS_TOKEN}" "$${API_URL}/runners?per_page=100" | \
to
curl -sS --header "PRIVATE-TOKEN: $${PERSONAL_ACCESS_TOKEN}" "$${API_URL}/runners/all?per_page=100" | \
in line 93 and 88
You see the /all in the api call?
And if you use it for shared runners you need to update line 94 and 89 from
jq -c ".[] | select(false==.is_shared) | select(\"online\"!=.status) | .id" | \
to
jq -c ".[] | select(true==.is_shared) | select(\"online\"!=.status) | .id" | \

i made this changes a long time ago in my private repos but in general its for deleting runners only and should work without this changes

Thank You <3