update kubernetes deployment with jenkins

Question

I'm using Kubernetes Continuous Deploy Plugin to deploy and upgrade a Deployment on my Kubernetes Cluster. I'm using pipeline and this is the Jenkinsfile:

pipeline {
    environment {
        JOB_NAME = "${JOB_NAME}".replace("-deploy", "")
        REGISTRY = "my-docker-registry"
    }
    agent any
    stages {
        stage('Fetching kubernetes config files') {
            steps {
                git 'git_url_of_k8s_configurations'
            }
        }
        stage('Deploy on kubernetes') {
            steps {
                kubernetesDeploy(
                    kubeconfigId: 'k8s-default-namespace-config-id',
                    configs: 'deployment.yml',
                    enableConfigSubstitution: true
                )
            }
        }
    }
}

Deployment.yml instead is:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: ${JOB_NAME}
spec:
  replicas: 1
  template:
    metadata:
      labels:
        build_number: ${BUILD_NUMBER}
        app: ${JOB_NAME}
        role: rolling-update
    spec:
      containers:
      - name: ${JOB_NAME}-container        
        image: ${REGISTRY}/${JOB_NAME}:latest
        ports:
        - containerPort: 8080
        envFrom:
            - configMapRef:
                name: postgres
      imagePullSecrets:
      - name: regcred
  strategy:
    type: RollingUpdate

In order to let Kubernetes understand that Deployment is changed ( so to upgrade it and pods ) I used the Jenkins build number as annotation:

...
metadata:
  labels:
    build_number: ${BUILD_NUMBER}
...

The problem or my misunderstanding:

If Deployment does not exists on Kubernetes, all works good, creating one Deployment and one ReplicaSet.

If Deployment still exists and an upgrade is applied, Kubernetes creates a new ReplicaSet:

Before first deploy

First deploy

Second deploy

Third deploy

As you can see, each new Jenkins deploy will update corretly the deployment but creates a new ReplicaSet without removing the old one.

What could be the issue?

Answer 1

sample pipline

pipeline {
    agent any
    tools {nodejs "node"}
    environment {
        CI = 'true'
        PROJECT_ID = 'marshmallow'
        CLUSTER_NAME = 'cluster-1'
        LOCATION = 'us-central1-c'
        CREDENTIALS_ID = 'kubernetes'
        DOCKER_FILE_PATH="${FOLDER_NAME}/Dockerfile"
        SERVICE_NAME='auth'
        FOLDER_NAME='prod-config'
        K8_FILE_PATH="${FOLDER_NAME}/k8.yaml"
        IMAGE_TAG = "us.gcr.io/${PROJECT_ID}/${SERVICE_NAME}:${env.BUILD_NUMBER}"
    }
    
    stages {
        stage('Scm Checkout') {
            steps {
                checkout scm
            }
        }
        stage('Build') {
            steps {
                dir("${SERVICE_NAME}/"){
                  sh 'npm install'
                }
            }
        }
        
        stage('Build Docker Image') {
            steps {
                sh 'whoami'
                script {
                    dockerImage = docker.build("${IMAGE_TAG}","-f ${SERVICE_NAME}/${DOCKER_FILE_PATH} ${SERVICE_NAME}")
                }
            }
        }
        

        stage("Push Docker Image") {
            steps {
                script {
                    echo "Push Docker Image"
                    docker.withRegistry('https://us.gcr.io', "gcr:google-container-registry") {
                    dockerImage.push()
                }
                    
                }
            }
        }

        stage('Change image version') {
            steps {
                dir("${SERVICE_NAME}/prod-config"){
                  sh """
                    cat k8.yaml | grep image
                    sed -i 's|image: .*|image: "${IMAGE_TAG}"|' k8.yaml
                    cat k8.yaml | grep image
                    """
                }
            }
        }
        stage('Deploy to K8s') {
            steps{
                echo "Deployment started ..."
                sh 'ls -ltr'
                sh 'pwd'
                echo "Start deployment of ${SERVICE_NAME} service."
                step([
                    $class: 'KubernetesEngineBuilder',
                    projectId: env.PROJECT_ID, 
                    clusterName: env.CLUSTER_NAME, 
                    location: env.LOCATION, 
                    manifestPattern: "${SERVICE_NAME}/${K8_FILE_PATH}",
                    credentialsId: env.CREDENTIALS_ID, 
                    // verifyDeployments: true 
                 ])
                echo "Deployment Finished ..."
            }
        }
    }
    post {
        always {
           echo "Deleting docker iamge ..."
           sh "docker rmi -f ${IMAGE_TAG}"

        }
    }
}

Answer 2

This is expected behavior. Every time you update a Deployment a new ReplicaSet will be created. But, old ReplicaSet will be kept so that you can roll-back to previous state in case of any problem in your updated Deployment.

Ref: Updating a Deployment

However, you can limit how many ReplicaSet should be kept through spec.revisionHistoryLimit field. Default value is 10. Ref: RevisionHistoryLimit