Jenkins Image

June 7, 2018 · View on GitHub

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This repostory builds an image containing the Buildit Jenkins Fetcher and Jenkins Startup Scripts Runner. Both these components use the Jenkins Config Fetcher to fetch their configuration. Follow the link to the Jenkins Config Fetcher for instructions on how to configure the config location.

Sample

A sample Jenkins image can be launched by running the following command

docker run -it -e JENKINS_CONFIG_FILE=https://github.com/buildit/jenkins-config.git -e JENKINS_STARTUP_SECRET=43bc78d572aaa2df61e5cdb5b3725203 -e JAVA_OPTS=-Djenkins.install.runSetupWizard=false -p 8080:8080 builditdigital/jenkins-image:2.1.0-alpine

Once its up and running visit http://localhost:8080/ to see the Jenkins UI.

How It Works

  1. Jenkins Fetcher uses Jenkins Config Fetcher to get config in order to determine the jenkins war file to download.
  2. Once the war file is available, it is initiated using the “java -jar” command.
  3. The Jenkins Startup Scripts Runner is baked into the $JENKINS_HOME/init.groovy.d directory. As such it will be kicked off during the initialisation phase (see https://wiki.jenkins.io/display/JENKINS/Groovy+Hook+Script for more details).
  4. The runner again uses the Jenkins Config Fetcher to get the config to determine which Jenkins Startup Scripts archive to download and run.
  5. Once downloaded, the archive is unpacked and executed by kicking of the main method of the main.groovy file located in the root of the exploded archive.
  6. The main method loops round the list of scripts it has in its configuration, executing each one for which it has a corresponding config section available (e.g. the mail.groovy file is only executed if “config?.mail” evaluates to a non null value).