Kubernetes Pod Templates

The Kubernetes Plugin and Pod Templates

The Kubernetes 5,150 plugin (4557.ve746270f672f) treats a cluster as a cloud: for each build it creates a pod whose jnlp container runs the inbound agent, then deletes it. Here a one-node kind cluster, l2-agents, runs only agent pods, with Kubernetes's RBAC for Jenkins 8,793 (a jenkins namespace, a ServiceAccount and a Role limited to pods there); docker network connect kind l2-jenkins joins the controller to its network. The cloud uses a kubeconfig with the ServiceAccount's token (a Secret file credential), namespace jenkins, Jenkins URL http://l2-jenkins:8080/, WebSocket and at most two pods. The pod template lives in the Jenkinsfile:

k8s-pod: a pod agent with a jnlp and a node containerGroovy

pipeline {
  agent {
    kubernetes {
      cloud 'l2-agents'
      defaultContainer 'node'
      yaml '''
        spec:
          containers:
          - name: jnlp
            image: jenkins/inbound-agent:latest-jdk21
            resources: {requests: {cpu: 100m, memory: 256Mi}, limits: {memory: 512Mi}}
          - name: node
            image: node:24-alpine
            command: [sleep, infinity]
            resources: {requests: {cpu: 250m, memory: 256Mi}, limits: {cpu: 1, memory: 768Mi}}
      '''
    }
  }
  stages {
    stage('Install') {
      steps {
        container('jnlp') {
          git url: 'https://github.com/binarybehemoth/booknest-jenkins.git', branch: 'main'
        }
        sh 'echo "$NODE_NAME: node $(node --version)" && npm ci --no-audit --no-fund'
      }
    }
  }
}

Output

Created Pod: l2-agents jenkins/k8s-pod-7-14859-b6hrr-0dkxl
...
k8s-pod-7-14859-b6hrr-0dkxl: node v24.21.0
...
added 82 packages in 3s

defaultContainer 'node' sends each sh to the Node.js 2,131 container, which shares the workspace with jnlp; Git 1,932 runs in jnlp because Alpine 13,255 's Node image lacks it. The pod agent exists only while its build runs:

The Nodes page during a k8s-pod build: permanent agents, the built-in node and a pod agent

Build 7 took 17 seconds, pod creation included (the very first pod took four minutes to connect). kind load docker-image failed here ("content digest ... not found"), so docker save --platform linux/amd64 ... | ctr images import loaded the images instead.

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Kubernetes Pod Templates