Forked from https://gitlab.com/boiko.ivan/merge-requests-triggers

What is it

Synopsis

This application allows to trigger pipelines for Merge Requests in GitLab CI.

This is done by acting as external HTTP service, registered in GitLab as a WebHook.
It listens on events for Merge Requests, and if there is a new commit it calls GitLab API to create a Pipeline.

It can be used to:

• run builds only for Merge Requests, if building on each git push creates too much load on build queue
• allow a different workflow for Merge Requests, as it passes env var CI_MERGE_REQUEST=true that you use in your script

At the moment of writing there is no such standard functionality in GitLab, see: https://gitlab.com/gitlab-org/gitlab-ce/issues/23902

Features

Application has the following features:

• if pipeline already exists for the latest commit in MR, it does not trigger new one to avoid duplication
• does not create pipelines for "Work In Progress" MRs
• cancels redundant jobs - which are in "pending" state and part of the already "running" older pipelines
• for just created MRs enables "Remove source branch" flag
• has a separate _ping endpoint returning HTTP 200, to be used for monitoring
• does not support forks

Application can serve multiple Git projects simultaneously, as it runs with user's private token.

How to use it

Configure docker compose environment

• Open .env for edit
  • PUBLISHED_PORT: where the webhook will listen (eg. 9099)
  • GITLAB_INSTANCE_ADDRESS: the address of your gitlab (eg. https://gitlab.com/)
  • GITLAB_API_TOKEN: your private access token (see step later)
  • TRIGGER_MERGED: wether trigger pipeline for a merged MR (true / false)
  • REMOVE_SOURCE_EXCEPTIONS: Branches for which the remove_source_branch=true wont applied

Create Webhook

• Go to: Project -> Settings -> Integrations

• Add a new webhook for "Merge Request Events", pointing to the running service: http://<hostname>:<port>/webhook.json, where:

  • if running as a standalone Application\container - use hostname of the computer where it runs
  • if running as a Docker Stack without Load Balancer - use hostname of any node of the Docker Swarm, as it uses "ingress" overlay network with routing mesh.

Create private token

• Create new user. Ideally it should be admin or user who will have "Master" access to required projects
• Login as this user, click on avatar in the right top corner and click on "Settings"
• In the left menu click on "Access Tokens"
• Enter a name for new token, and optionally expiration date
• Check "Scopes" > "api"
• Click "Create personal access token"
• Generated token will be displayed once
• Copy it and use it as GITLAB_API_TOKEN below

Run docker compose

docker-compose up -d

GitLab CI

• In your gitlab-ci.yml you should put following lines to trigger merge requests:

only:
  - triggers

• You can use the following environment variables in your job:
  • CI_MERGE_REQUEST: if job was triggered my merge request, it will get true value
  • MR_TARGET_BRANCH: the target branch
  • MR_ID: the ID of the merge request
  • MR_IID: the IID of the merge request
  • MR_STATE: the state of the merge request (eg. merged / opened / etc)

[Optional] Require Merge Requests to be built

• Go to: Project -> Settings -> General -> "Merge request settings"
• Enable: "Only allow merge requests to be merged if the pipeline succeeds"