Maintainable Jenkins

Goals

• Manage plugins with specific versions.
• Configure Jenkins automatically.
• Configure Jenkins jobs automatically.
  • Externalise job config from the docker file to support quick additions of jobs.
• Use multiple docker files to share binary data such as plugins.

Decisions

Plugins

Plugins are managed in one file (plugins.yaml) and versions are pinned for clarity and stability.

Jenkins Version

The Jenkins version is pinned in the Dockerfile.

Jenkins Configuration

Jenkins is configured on startup using the JCasC plugin. This includes:

• Approved signatures.
• Creating the initial seed job.

Seed Job

A single job is configured to be created on startup, the seed job. This job is responsible for taking a remote job DSL file and then setting up the rest of the jobs.

This allows us to add/remove jobs without having to rebuild the docker image or restart the instance.

Docker Image

The docker image should be as simple as possible. Ideally we should expose docker to the Jenkins container (i.e. by exposing the docker sock file) and run complex tasks inside docker images. This avoids us having to install and manage many apps ourselves (such as Python)!

Further Improvements

• You can pass in the JCasC config file via a volume, allowing you to update this file without rebuilding the image.
• Deploy on K8.

Docs

• https://verifa.io/blog/getting-started-with-jenkins-config-as-code/
• https://github.com/jenkinsci/job-dsl-plugin/wiki/JCasC

Usage

Requirements:

• Docker
• Docker compose

Building and Testing

1. make build.
2. make run.
3. Login at localhost:8080. You can find the admin password by checking the logs (make logs).
4. Run the seed job manually. You will need to approve the new jobs in the script approval window.