Jenkins：从 GitHub 网络钩子触发构建的作业仅在主节点上运行

Question

The initial idea was to trigger a specific build on a specific node (slave), after merging changes to master branch on GitHub.

Configuration:

1. Jenkins (ver 2.226) is on a Centos8 VM machine in VirtualBox;
2. VM setup: Java 11 OpenJDK(openjdk version "11.0.5"), git version 2.18.2

Steps done:

1. Created a Jenkins project (job) that clones a Github repo and runs some mvn commands on it;
2. Configured the job to run on a new node, except from the master node;

As expected: The job runns properly.

3. I used ngrok to expose my Jenkins server and generate an external link to it;
4. Added the ' http://bla.ngrok.io/github-webhook/ ' payload url to GitHub;

As expected: I can ping the Jenkins server successfully.

5. In Jenkins I configured the job to be triggered trought SCM (enabled 'GitHub hook trigger for GITScm polling');
6. Then I go to GitHub and commit a change to the master branch.

Actual results: The build is triggered but only on the Master node.

7. I marked as offline the Master node as to force the triggered job to be executed on the new slave. Actual results: Nothing happens.

8. I enabled the Master node and tried to trigger the job again. Actual results: Nothing happens.

I have tail-ed the jenkins.log file to see what happens, and the 'poked build' action is recorded. After this, probably it waits to execute the build but this never happens. At the end the 'Periodic background build discarder' is started.

2020-03-24 21:35:11.733+0000 [id=16]    INFO    o.j.p.g.w.s.DefaultPushGHEventSubscriber#onEvent: Received PushEvent for https://github.com/some/some_project from [someip] ⇒ http://blah.ngrok.io:8080/github-webhook/
2020-03-24 21:35:11.734+0000 [id=16]    INFO    o.j.p.g.w.s.DefaultPushGHEventSubscriber$1#run: Poked simple_build
2020-03-24 21:39:07.386+0000 [id=206]   INFO    hudson.model.AsyncPeriodicWork#lambda$doRun$0: Started Periodic background build discarder
2020-03-24 21:39:07.403+0000 [id=206]   INFO    hudson.model.AsyncPeriodicWork#lambda$doRun$0: Finished Periodic back

Am I missing something?

Is the web-hook trigger build action restricted to execute only on the Master node?

Answer 1

I have managed to find a solution to the problem. Now builds are triggered and run on the node that was set in the build configuration screen.

What I have done is to set the master node to be used only when it is needed.

To do this you need to:

• Go to 'Manage Jenkins > Configure System' and on the 'Usage' field selected the 'Only build jobs with label expression matching this node'
• Save the settings.