Month: July 2020

Jenkins Maven Agent for Kubernetes

Posted on by dojocube

jenkins-pipeline-for-kubernetes-cluster

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 mins)

 

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

jenkins-maven-agent-pod-template

 

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

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

jenkins-add-new-volume

 

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.

jenkins-console-output

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

 

Last, this is the build console output:

jenkins-maven-agent-finished-success

jenkins-maven-agent-build-success

 

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

jenkins-maven-agent-build-time-reduced

 

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    default-scheduler  persistentvolumeclaim "maven-agent-pvc" not found
  Warning  FailedScheduling    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

maven-agent-no-such-file-or-directory

 

Waiting for next available executor

jenkins-waiting-for-next-available-executor

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