How to trigger a Jenkins 2.0 Pipeline job from a GitHub pull request

Question

It looks like the GitHubPullRequestBuilder is not compatible with Jenkins v2.0 pipeline jobs.

How do you configure a pipeline job to be triggered from a GitHub pull request event?
The documentation on this topic is sparse and I cannot find any examples of this. Or is it better to create a web-hook in GitHub to trigger the pipeline job on the PR event?

Answer 1

I had similar issue. Here’s what worked for me

Pre-req

• Jenkins ver. 2+ (I was using Jenkins 2.60)
• Github (or Githhub enterprise) account
• Your github and Jenkins must be able to talk to each other.

On Github

1. create a github Personal Access Token (PAT) with relevant rights.
2. For your repo, create a webhook with
   • URL as YourJenkinsURL/github-webhook/
   • Choose ‘Let me select individual events’ and check ‘Pull Request’
3. Add a Jenkinsfile to the root folder of your repo. For testing purpose you could put content as a basic hello world like below

    pipeline {
        agent any
        stages {
            stage('Test') {
                steps {
                    echo 'Hello World ...'
                }
            }
        }
    }

On Jenkins

1. Install GitHub Pull Request Builder plugin. (You also need “Github” plugin but that should normally be installed as part of Jenkins ver 2+)
2. Jenkins – Credentials
   • Add github Personal Access Token (PAT) as a ‘secret text’ credential.
   • Add github username-password as ‘username-password’ credential.
3. Manage Jenkins – Configure System
   • Github – Github Servers : This is part of the Github plugin. Add a github server. ‘API URL’ It will default to https://api.github.com. If you are using enterprise github, replace with enterprise github url followed by /api/v3. For credential select the PAT option. Test the connection. ‘Manage Hooks’ is checked.
   • GitHub Pull Request Builder : for ‘GitHub Server API URL’ use same url as specified in Github Server section. Leave ‘Shared Secret’ blank. For credentials use ‘username-password’ credential. Test credentials to ensure its working. In my settings, ‘Auto-manage webhooks’ was checked.
4. Pipeline Job
   • Create a new item using ‘Pipeline’ option. Note: This is the vanilla Pipeline job, not Multibranch Pipeline.
   • General Section: Check ‘Github Project’ – Project URL : Enter your github repo url
   • Build Triggers: Check ‘GitHub Pull Request Builder’
     • For ‘GitHub API credentials’ select option you set for GitHub pull request builder in ‘Manage Jenkins – Configure System’ screen
     • For admin list: add your username
     • Check Use github hooks for build triggering
   • Pipeline:
     1. Select ‘Pipeline Script from SCM’. Note this assumes that the root folder of your repo will contain a ‘Jenkinsfile’
     2. SCM: Select ‘Git’
     3. Repositories – enter repo detail. For credentials use ‘username-password’ based credentials.
     4. Click Advanced and add refspec as +refs/pull/*:refs/remotes/origin/pr/*
     5. Branch – should be ${sha1}
     6. Script Path: defaulted to Jenkinsfile, leave as is.
     7. Lightweight Checkout - Uncheck this (https://github.com/jenkinsci/ghprb-plugin/issues/507)

That’s it. You are all set. Creating a PR on master branch of your repo should now trigger your Jenkins Pipeline job

Some observations

• Redelivering the webhook payload of a PR from github does not trigger the pipeline but opening a new PR or even re-opening a closed PR on github, triggers the pipeline job
• In Pipeline Job Configuration, if you choose “Pipeline Script” and paste your pipeline script in there, the job doesn't trigger !!!