Jenkins Pull Request builder ignoring branches with ${sha1}

Question

I\'m attempting to set up the Jenkins PR builder plugin to hit github on new pull request. I\'ve followed along with the docs, and have tried \"many\" different

Answer 1

It appears, based on the refspec of +refs/pull/*:refs/remotes/origin/pr/* that you want this project to build pull requests only.

However, it seems that you have the Poll SCM trigger enabled along with the Github Pull Request Builder (GHPRB) trigger.

Remember, the GHPRB plugin is already a trigger. The only reason to enable additional triggers would be if you want to have this project also build normal branches. If this is the case, please see the bottom of this post for some more information about this use-case.

So step one is to make sure that the only trigger enabled is the GHPRB plugin.

The next step is to recognize that you are not using Github webhooks - likely due to firewall constraints. This means you are using a cronjob that will use the Github API to check for Pull Request updates and compare it to the last poll to detect changes.

This means that your credentials must be correct, first of all. You can check the credentials in the System Settings portion of Jenkins (you must be an Admin) under the GHPRB plugin section. Make sure the credentials have all the rights needed to view, comment, etc. your repository.

If all of that is correct, the logs will likely give you more information. If you are an admin, you can go to Manage Jenkins and find System Log. By viewing the log, you'll likely find errors that are related to your problem.

In your case, since I'm your sysadmin and am typing all of this for the benefit of a 3rd party who may come by, I noticed that we were seeing FileNotFound exceptions being thrown from the GitHub plugin when it attempted to access the API.

The cause?

The GHPRB plugin uses the Github plugin to communicate with the API and, thus, poll for Pull Requests. The Project url field of the Github Plugin is used to generate the API URLs for the poll requests.

Remove the .git portion of the URL! Even though it will work perfectly find when going to the URL in your browser, if you add the .git suffix to the project name in the API it gets angry and will give you a 404. By removing this suffix from the Project url field, the GitHub plugin will parse the correct URL path for the API requests and life is good.

Building PRs and Normal Branches

In order to use a single Jenkins project for both Pull Requests and normal branches, you need to do a few extra things.

1. Enable a trigger for the other branches such as GitHub hooks or SCM Polling
2. Update the refspec configuration to include not only the pull request refspec you have configured currently, but also the refspec(s) of the branches you wish to be built. For example, if you wanted all tags and branches to be available for building, you would use +refs/pull/*:refs/remotes/origin/pr/* +refs/heads/*:refs/remotes/origin/*
3. Because the branch specifier is normally set to ${sha1} for building PRs and this environment variable is not created unless the build is triggered by the GHPRB plugin, you will want convert this project into a Parametarized Build and create a parameter called sha1 with a default value equal to the branch(es) you would normally have put under Branch Specifier if you weren't using the GHPRB plugin, and then ensure that the Branch Specifier field references the ${sha1} variable. The GHPRB plugin will override this parameter if it is used to trigger the build, otherwise the default value will be used for other triggers. This also gives you a chance to manually run builds by specifying the parameter from the UI (or a script) at build-time.

You may need a few other tweaks, but those are the main ones that come to mind immediately.