Used to integrate Jenkins with Github to aid in auto landing branches that have been reviewed and approved for landing into the 'trunk' branch of the project.

• Pull request is created
• Code review happens and tests are run from an outside Jenkins job. (We use the Github pull request builder plugin)
• Once code receives a LGTM, the author places a keyword "$$merge$$" into a final comment on the pull request.
• This webservice, via a hook notification from Github, triggers a merge job in jenkins.
• If all tests pass, the Jenkins server will ping back that this pull request is good and passes all tests.
• This web service then triggers a merge via the Github API to land the branch.

The service does not have to be, but it can be installed on your Jenkins server. The steps below walk through a sample setup process.

ssh ci.com
sudo su jenkins
cd ~
git clone https://github.com/juju/jenkins-github-lander.git
cd jenkins-github-lander
make all
make development.ini
# Hack the INI settings for the jenkins server and the github project/bot user.

# Add cron job per README

# Add to the -merge job's build steps the final step of:
cd /var/lib/jenkins/jenkins-github-lander && ./bin/lander-merge-result --ini development.ini --pr=${pr} --build=${BUILD_NUMBER}

Update the INI file used to launch the web service with the following configuration keys.

jenkins.merge.url = http://ci.jujusomething.com/job/{}/buildWithParameters
jenkins.merge.job = juju-gui-merge
jenkins.merge.token = jenkinsbuildtoken
jenkins.merge.trigger = $$merge$$

github.apiurl = https://api.github.com
github.username = github-bot
github.token = github-bot-auth-token
github.owner = Juju
github.project = juju-gui

Jenkins is charged with running the actual build testing that a pull request is correct and ready to merge. At the end of the build script for your job, the service must be triggered with a command to either merge the pull request or that a pull request build failed. In the case of a failure, the service will add a comment to the pull request stating that, and linking back to the Jenkins job to aid in debugging.

A build should exit on the first command in the build that returns a non-successful error code. To indicate success, the command only needs to be the last item in the build script.

Please indicate the pull request number so the script can properly close the correct one. Also make sure to indicate the build number from Jenkins so that the link to this build can be constructed. The build number should be available in the ENV within $BUILD_NUMBER.

Note that this is not to be run from the build. It will not have the correct INI file.

cd /$path/to/service/venv/ && \
./bin/lander-merge-result --ini development.ini --pr=5 --job-name=project-merge --build-number=25

To indicate a build has failed, you'll need to trigger the command after the build has run and failed. There are a couple of different Jenkins plugins that can assist with this.

• https://wiki.jenkins-ci.org/display/JENKINS/PostBuildScript+Plugin
• https://wiki.jenkins-ci.org/display/JENKINS/Post+build+task

Please indicate the pull request for updating. Also make sure to indicate the build number from Jenkins so that the link to this build can be constructed. The build number should be available in the ENV within $BUILD_NUMBER.

cd /$path/to/service/venv/ && \
./bin/lander-merge-result --ini development.ini --failure="Build failed" --pr=5 --job-name=project-merge --build-number=25

TBD

You can run the service as a cron script to avoid needing to bring up a web service. It will then just poll open pull requests for comments with the magic landing trigger. In this case, then the jenkins build job must run the final landing merge script vs ping'ing the web server with the url.

Since this is time based, and it polls all open pull requests, the order of landing might not match the real order of comments on the pull requests.

*/3 * * * * cd /$path/to/service/venv/ && ./bin/lander-check-pulls --ini development.ini

Currently the only way it works is to run manually. Copy the sample.ini file into development.ini and update the config for your jenkins/github configuration.

Once set, you can make run to start the webserver and the url /check_pulls will become functional. If there are no pull requests that are mergable, it'll respond so, and if it does kick off a merge job, it will reply with the pull request id and the sha of the merge point.

$ http://127.0.0.1:6543/check_pulls
Kicking pull request: 5 at sha 089635fe2be2341cdbb8a3be093523798b918430