Declarative Jenkins Pipeline use existing Kubernetes Pod Template

Question

I am using the OpenShift Jenkins image within an OpenShift Cluster. This default Jenkins image results in a Jenkins container that is preconfigured to point to my Kubernetes cluster. Additionally, the container has two Kubernetes pod templates defined, one for maven and one for nodejs.

What I would now like to do is use a declarative pipeline and reference these pods. I tried the following

  agent {
     kubernetes {
     //cloud 'kubernetes'
     label 'maven'
     }
  }

But that gives an error stating

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:

WorkflowScript: 4: Missing required parameter for agent type "kubernetes": containerTemplate @ line 4, column 10.

        kubernetes {

        ^

All of the (examples) that I can find for declarative pipelines show the pod templates being defined when the agent is specified.

Is it possible to reuse already defined templates in a declarative pipeline?

Answer 1

Here is an example using a pre-defined pod template.

pipeline {
  agent {
      label "maven"
  }
  stages {
    stage('Run maven') {
      steps {
        sh 'mvn -version'
      }
    }
  }
}

Your original pipeline definition was in effect defining a brand new pod template and hence the error enforcing the requirement for containerTeamplates parameter. When using an existing template, you can simply specify the label in the agent block.