Wednesday, November 25, 2020

Deploy Python App into Kubernetes Cluster using kubectl in Jenkins Pipeline | Containerize Python App and Deploy into Kubernetes Cluster

 We will learn how to automate Docker builds using Jenkins and Deploy into Kubernetes Cluster. We will use Python based application. I have already created a repo with source code + Dockerfile. The repo also have Jenkinsfile for automating the following:


- Automating builds using Jenkins
- Automating Docker image creation
- Automating Docker image upload into Docker registry
- Automating Deployments to Kubernetes Cluster
 
Pre-requistes:
1. Jenkins Master is up and running. 
2. Spin up Jenkins slave, install docker in it. Install kubectl on Slave.
3. Docker, Docker pipeline and Kubernetes Deploy plug-ins are installed in Jenkins



4. Docker hub account setup in https://cloud.docker.com
5. Kubernetes Cluster is setup and running.

Step #1 - Login to Jenkins slave instance through command line - Install Docker

sudo apt install docker.io -y
 
Add Jenkins to Docker Group
sudo usermod -aG docker jenkins

sudo systemctl daemon-reload
 
Restart Docker service
sudo systemctl start docker
sudo systemctl enable docker
sudo systemctl restart docker


Restart Jenkins service
sudo service jenkins restart
 
Install kubectl command on Jenkins slave.

Step #2 - Create Credentials for Docker Hub
Go to Jenkins UI, click on Credentials -->


Click on Global credentials
Click on Add Credentials


Now Create an entry for your Docker Hub account. Make sure you enter the ID as dockerhub

Step #3 - Create Credentials for Kubernetes Cluster
execute the below command to get kubeconfig info, copy the entire content of the file:
sudo cat ~/.kube/config

Go to Jenkins, Manage Jenkins, Click on Add Credentials, use Kubernetes configuration from drop down.
Enter ID as kubeconfig_raw and upload kubeconfig file


 Click on browse
Upload kube config and enter id as ID kubeconfig-raw

Step # 4 - Create a pipeline in Jenkins
Create a new pipeline job.


Step # 5 - Copy the pipeline code from below
Make sure you change red highlighted values below:
Your docker user id should be updated.
your registry credentials ID from Jenkins from step # 1 should be copied

pipeline {
     agent {
         label 'myslave'
     }
        environment {
        //once you sign up for Docker hub, use that user_id here
        registry = "your_docker_hub_user_id/mypython-app"
        //- update your credentials ID after creating credentials for connecting to Docker Hub
        registryCredential = 'dockerhub'
        dockerImage = ''
    }
    stages {

        stage ('checkout') {
            steps {
            checkout([$class: 'GitSCM', branches: [[name: '*/master']], doGenerateSubmoduleConfigurations: false, extensions: [], submoduleCfg: [], userRemoteConfigs: [[url: 'https://github.com/akannan1087/myPythonDockerRepo']]])
            }
        }
       
        stage ('Build docker image') {
            steps {
                script {
                dockerImage = docker.build registry
                }
            }
        }
       
         // Uploading Docker images into Docker Hub
    stage('Upload Image') {
     steps{   
         script {
            docker.withRegistry( '', registryCredential ) {
            dockerImage.push()
            }
        }
      }
    }
   
       stage('K8S Deploy') {
        steps{   
            script {
                withKubeConfig([credentialsId: 'kubeconfig-raw', serverUrl: '']) {
                sh ('kubectl apply -f k8s-deployment.yaml')
                }
            }
        }
       }
  
    }  
}

Step # 6 - Build the pipeline
Once you create the pipeline and changes values per your Docker user id and credentials ID, click on 

Step # 7 - Verify deployments to K8S

kubectl get pods


kubectl get deployments
kubectl get services

Steps # 8 - Access Python App in K8S cluster
Once build is successful, go to browser and enter master or worker node public ip address along with port number mentioned above
http://master_or_worker_node_public_ipaddress:port_no_from_above

You should see page like below:




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