Customizing Jenkins

How to customize Jenkins

Jenkins can be customized with plugins. Plugin’s configuration is applied as groovy scripts or the configuration as code plugin. Any plugin working for Jenkins can be installed by the Jenkins Operator.

Pre-installed plugins:

configuration-as-code v1.55
git v4.10.0
job-dsl v1.78.1
kubernetes-credentials-provider v0.20
kubernetes v1.30.11
workflow-aggregator v2.6
workflow-job v2.42

Rest of the plugins can be found in plugins repository.

Install plugins

Edit Custom Resource under spec.master.plugins:

apiVersion: jenkins.io/v1alpha2
kind: Jenkins
metadata:
  name: example
spec:
  master:
   plugins:
   - name: simple-theme-plugin
     version: "0.7"

Under spec.master.basePlugins you can find plugins for a valid Jenkins Operator:

apiVersion: jenkins.io/v1alpha2
kind: Jenkins
metadata:
  name: example
spec:
  master:
    basePlugins:
    - name: kubernetes
      version: "1.30.11"
    - name: workflow-job
      version: "2.42"
    - name: workflow-aggregator
      version: "2.6"
    - name: git
      version: "4.10.0"
    - name: job-dsl
      version: "1.78.1"
    - name: configuration-as-code
      version: "1.55"
    - name: kubernetes-credentials-provider
      version: "0.20"

You can change their versions.

The Jenkins Operator will then automatically install plugins after the Jenkins master pod restart.

Apply plugin’s config

By using a ConfigMap you can create your own Jenkins customized configuration. Then you must reference the ConfigMap in the Jenkins pod customization file in spec.groovyScripts or spec.configurationAsCode

Create a ConfigMap with specific name (eg. jenkins-operator-user-configuration). Then, modify the Jenkins manifest:

apiVersion: jenkins.io/v1alpha2
kind: Jenkins
metadata:
  name: example
spec:
  configurationAsCode:
    configurations:
    - name: jenkins-operator-user-configuration
  groovyScripts:
    configurations:
    - name: jenkins-operator-user-configuration

Here is an example of jenkins-operator-user-configuration:

apiVersion: v1
kind: ConfigMap
metadata:
  name: jenkins-operator-user-configuration
data:
  1-configure-theme.groovy: |
    import jenkins.*
    import jenkins.model.*
    import hudson.*
    import hudson.model.*
    import org.jenkinsci.plugins.simpletheme.ThemeElement
    import org.jenkinsci.plugins.simpletheme.CssTextThemeElement
    import org.jenkinsci.plugins.simpletheme.CssUrlThemeElement

    Jenkins jenkins = Jenkins.getInstance()

    def decorator = Jenkins.instance.getDescriptorByType(org.codefirst.SimpleThemeDecorator.class)

    List<ThemeElement> configElements = new ArrayList<>();
    configElements.add(new CssTextThemeElement("DEFAULT"));
    configElements.add(new CssUrlThemeElement("https://cdn.rawgit.com/afonsof/jenkins-material-theme/gh-pages/dist/material-light-green.css"));
    decorator.setElements(configElements);
    decorator.save();

    jenkins.save()    
  1-system-message.yaml: |
    jenkins:
      systemMessage: "Configuration as Code integration works!!!"

*.groovy is Groovy script configuration
*.yaml is configuration as code

If you want to correct your configuration you can edit it while the Jenkins Operator is running. Jenkins will reconcile and apply the new configuration.

How to use secrets from a Groovy scripts

If you configured spec.groovyScripts.secret.name, then this secret is available to use from map Groovy scripts. The secrets are loaded to secrets map.

Create a secret with for example the name jenkins-conf-secrets.

kind: Secret
apiVersion: v1
type: Opaque
metadata:
  name: jenkins-conf-secrets
  namespace: default
data:
  SYSTEM_MESSAGE: SGVsbG8gd29ybGQ=

Then modify the Jenkins pod manifest by changing spec.groovyScripts.secret.name to jenkins-conf-secrets.

apiVersion: jenkins.io/v1alpha2
kind: Jenkins
metadata:
  name: example
spec:
  configurationAsCode:
    configurations:
    - name: jenkins-operator-user-configuration
    secret:
      name: jenkins-conf-secrets
  groovyScripts:
    configurations:
    - name: jenkins-operator-user-configuration
    secret:
      name: jenkins-conf-secrets

Now you can test that the secret is mounted by applying this ConfigMap for Groovy script:

apiVersion: v1
kind: ConfigMap
metadata:
  name: jenkins-operator-user-configuration
data:
  1-system-message.groovy: |
    import jenkins.*
    import jenkins.model.*
    import hudson.*
    import hudson.model.*
    Jenkins jenkins = Jenkins.getInstance()

    jenkins.setSystemMessage(secrets["SYSTEM_MESSAGE"])
    jenkins.save()

Or by applying this configuration as code:

apiVersion: v1
kind: ConfigMap
metadata:
  name: jenkins-operator-user-configuration
data:
  1-system-message.yaml: |
    jenkins:
      systemMessage: ${SYSTEM_MESSAGE}

After this, you should see the Hello world system message from the Jenkins homepage.

Last modified December 8, 2021