GitLab Runners as a Service with Github Action

TL;DR; This article will show how to implement the action "Gitlab Runner Service Action" in a "GitHub Workflow" that is triggered by a "GitLab-CI job", and this way having temporary GitLab Runners hosted by GitHub.

For more info about GitHub workflow, check the official documentation

For more info about GitLab-CI, check the official documentation

Steps

Step 1

Create a new GitHub repository with the following GitHub Workflow. File location: .github/workflows/gitlab-runner.yaml

name: Gitlab Runner Service on: [repository_dispatch] jobs: build: runs-on: ubuntu-latest steps: - name: Maximize Build Space uses: easimon/maximize-build-space@master with: root-reserve-mb: 512 swap-size-mb: 1024 remove-dotnet: 'true' remove-android: 'true' remove-haskell: 'true' - name: Gitlab Runner uses: edersonbrilhante/gitlab-runner-action@main with: registration-token: "${{ github.event.client_payload.registration_token }}" docker-image: "docker:19.03.12" name: ${{ github.run_id }} tag-list: "crosscicd" 

What does this workflow do?

This workflow will run just when the event repository_dispatch is triggered. The first step will be to increase the free space removing useless packages for our GitLab runner. And the second step will run the action that registers a new GitLab Runner with a tag crosscicd, so start it and unregister it after a GitLab-CI job is completed with success or failure.

Step 2

Create a new GitLab repository with the following GitLab-CI config. File location: .gitlab-ci.yml

start-crosscicd: image: alpine before_script: - apk add --update curl && rm -rf /var/cache/apk/* script: | curl -H "Authorization: token ${GITHUB_TOKEN}" \ -H 'Accept: application/vnd.github.everest-preview+json' \ "https://api.github.com/repos/${GITHUB_REPO}/dispatches" \ -d '{"event_type": "gitlab_trigger_'${CI_PIPELINE_ID}'", "client_payload": {"registration_token": "'${GITLAB_REGISTRATION_TOKEN}'"}}' github: image: docker:latest services: - name: docker:dind alias: thedockerhost variables: DOCKER_HOST: tcp://thedockerhost:2375/ DOCKER_DRIVER: overlay2 DOCKER_TLS_CERTDIR: "" script: - df -h - docker run --privileged ubuntu df -h tags: - crosscicd 

What does this gitlab-ci?

The job start-crosscicd will trigger the GitHub workflow, creating the GitLab runner with the tag crosscicd. And the job GitHub will wait for a runner with a tag crosscicd.

Step 3

Set the EnvVars in the new GitLab Repo

 GITHUB_REPO:<username>/<github-repo> GITHUB_TOKEN:<GitHub Access Token> GITLAB_REGISTRATION_TOKEN:<GitLab Registration Token> 

How to create a new GitHub Access Token:

• Go to https://github.com/settings/tokens/new

• Mark the item workflow and click in generate a token

How to get Registration Token:

• Go to https://gitlab.com/<username>/<repo>/-/settings/ci_cd and click and expand Runners

• Copy the Registration Token

Where to store the EnvVars?

• Go to https://gitlab.com/<username>/<repo>/-/settings/ci_cd and click and expand Variables

• Click in Add Variable and save it for each EnvVar

Step 4

Now your pipeline is ready to run the GitLab Runner in GitHub trigger by Gitlab-CI Job :)

Example

Video Demo

Screenshots

Code

• Repo with example code

• GitHub Action

That’s it!

In case you have any questions, please leave a comment here or ping me on 🔗 LinkedIn.