jenkins4casc

Repository for the Praqma custom Docker image using the new Configuration as Code plugin.

How to use the Docker image

Basically the same way as you would use the official Jenkins Docker image. With one difference. If you start a container using this image with an environment variable CASC_JENKINS_CONFIG you can configure Jenkins to be configured on startup. And if you point to a configuration file from an URL you can reconfigure without the need for a restart.

Example: Minimum Configuration

docker run -p 8080:8080 -p 50000:50000 -v jenkins_home:/var/jenkins_home -e CASC_JENKINS_CONFIG=https://raw.githubusercontent.com/Praqma/jenkins4casc/master/jenkins-minimal-example.yaml praqma/jenkins4casc

We added the switch

-e CASC_JENKINS_CONFIG=https://raw.githubusercontent.com/Praqma/jenkins4casc/master/jenkins-minimal-example.yaml

To point to the smallest possible configuration of Jenkins with Jenkins configuration as code:

jenkins:
  systemMessage: "The smallest possible configuration for Jenkins Configuration as Code plugin"

This gives this message on the welcome screen when Jenkins boots up:

For more advanced examples take a look at the demos sections found in the official repository for Configuration as Code plugin repository

Example using Docker Compose and Docker secrets

We have a running example using Docker compose you're free to take a look at located here.

Docker image versioning strategy

The tag latest always refer to an image build from HEAD on master. When we do an official release we create a tag corresponding to the version of the included plugin. For instance, at the time of this writing the latest version of the plugin is 0.2-alpha when the Docker image for this version is ready we'll release a version with the tag praqma/jenkins4casc:0.2-alpha and praqma/jenkins4casc:0.2-alpha-latest.

If we need to update the Docker image, with a change that is not related to a new version of the plugin we'll create a new version with the tag 0.2-alpha-1and update the tag praqma/jenkins4casc:0.2-alpha-latest.

Docker autobuild

To create a new docker image on Docker hub, simply tag your commit with a version tag as described above, try to match the version with the version of the included Configuration As Code plugin. So for instance if you create a tag: 0.7-alpha and push your change to github, you'll get a docker image with the label: jenkins4casc:0.7-alpha which is what you want.

The repository is setup with Docker autobuild enabled. We build all tags, and master is always built and made available as latest. Versioning is based on the convention described in the Docker image versioning strategy section above.

For more information about how Docker Hub autobuild works please consult the official guide.