By creating Jenkins Maven Agent for Kubernetes Cluster, you can improve build time of your maven builds

Jenkins Maven Agent on Kubernetes

(Total Setup Time: 15 mins)

Following up on the previous post, I will create a Jenkins Maven Agent for Kubernetes. By configuring a local maven m2 repository, you can save previous time on your builds.

Configuring Jenkins

(1 min)

First, navigate to Jenkins > Configure Clouds, and click on the Add Pod Template. I named the pod template as maven, with its usage set as:

Only build jobs with label expressions matching this node

Second, add a container with the following settings:

Name: jnlp
Dcoker image: docjoube/jenkins-agent:1.0
working directory: /home/jenkins/agent

Third, add a volume, with the following persistent volume claim:

Claim Name: maven-agent-pvc
Mount path: /home/jenkins/.m2

Fourth, insert the maven volume claims to the maven-pv.yaml:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: maven-agent-pv
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 2Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/hdd/master1k8s/app/maven/data"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: maven-agent-pvc
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi

Lastly, apply the maven-agent persistent volume and claims:

# Create the persistent volume and claim
kubectl apply -f maven-pv.yaml

# Create the data folder and change ownership
sudo mkdir -p /mnt/hdd/master1k8s/app/maven/data
sudo chown -R 1000:1000 /mnt/hdd/master1k8s/app/maven/data

Testing Jenkins Maven Agent

(14 mins)

First, modify Jenkinsfile to use maven agent and commit the change. You may refer to kubernetes plugin for more examples.

pipeline {
  agent none
    
  stages {
    stage('Build') {
      agent {
        label 'maven'
      }
      steps {
        checkout scm
        sh './mvnw -DskipTests clean package'
      }
    }
  }
}

Second, Jenkins automatically triggers a build.

You may notice that Jenkins master provisions a new maven-agent for this build.

Last, this is the build console output:

For subsequent builds, maven-agent uses the local maven m2 repository and hence significantly reducing the build time.

Troubleshooting

persistentvolumeclaim “maven-agent-pvc” not found

When the maven persistent volume is not created before any maven build, this error will occur. You can clear this error by creating the claim first.

Events:
  Type     Reason            Age        From               Message
  ----     ------            ----       ----               -------
  Warning  FailedScheduling  <unknown>  default-scheduler  persistentvolumeclaim "maven-agent-pvc" not found
  Warning  FailedScheduling  <unknown>  default-scheduler  persistentvolumeclaim "maven-agent-pvc" not found

No such file or directory

Because Jenkins user needs access rights to the maven persistent volume mount path, remember to change the folder ownership.

sudo chown -R 1000:1000 /mnt/hdd/master1k8s/app/maven/data

Waiting for next available executor

You can fix this error by following closely to this console output and removing the default values (/bin/sh -c and cat) from Jenkins > Configure Clouds.