Day 21: Kubernetes – CI/CD Pipelines with Kubernetes

Introduction to CI/CD Pipelines with Kubernetes

Continuous Integration (CI) and Continuous Deployment/Delivery (CD) are essential practices for modern application development. Kubernetes, being a powerful platform for container orchestration, integrates seamlessly with CI/CD pipelines to automate the building, testing, and deployment of applications.

This guide covers setting up a basic CI/CD pipeline, integrating popular tools like Jenkins or GitLab, and deploying applications to a Kubernetes cluster.

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What is a CI/CD Pipeline?

Continuous Integration (CI):

Automates the process of integrating code changes into a shared repository, followed by automated builds and tests.

Continuous Deployment/Delivery (CD):

Automates the release process, ensuring code changes are deployed to production (or staging) after passing the CI phase.

Benefits of CI/CD in Kubernetes:

• Automation: Streamlines the software delivery process.
• Consistency: Reduces human error.
• Scalability: Handles complex deployments with ease.
• Faster Time-to-Market: Speeds up the release cycle.

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Setting Up a CI/CD Pipeline

Step 1: Choose Your CI/CD Tool

Popular CI/CD tools compatible with Kubernetes include:

1. Jenkins
2. GitLab CI/CD
3. ArgoCD
4. Tekton

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Example: Setting Up CI/CD with Jenkins

Prerequisites:

• A running Kubernetes cluster.
• Jenkins installed (can be deployed as a Kubernetes pod).

Step 1: Deploy Jenkins on Kubernetes

1. Use Helm to install Jenkins:helm repo add jenkins https://charts.jenkins.io helm repo update helm install jenkins jenkins/jenkins --namespace jenkins --create-namespace
2. Access Jenkins:kubectl get svc -n jenkinsUse the external IP or NodePort to access the Jenkins UI.
3. Retrieve the admin password:kubectl exec --namespace jenkins -it svc/jenkins -c jenkins -- cat /run/secrets/chart-admin-password

Step 2: Configure Jenkins Pipeline for Kubernetes

1. Install necessary plugins:
   • Kubernetes Plugin
   • Pipeline Plugin
2. Create a Jenkinsfile:pipeline { agent { kubernetes { label 'jenkins-slave' yaml """ apiVersion: v1 kind: Pod spec: containers: - name: maven image: maven:3.6.3-jdk-11 command: - cat tty: true """ } } stages { stage('Build') { steps { sh 'mvn clean install' } } stage('Test') { steps { sh 'mvn test' } } stage('Deploy') { steps { kubernetesDeploy(kubeconfigId: 'k8s-config', configs: 'k8s/deployment.yaml') } } } }
3. Commit the Jenkinsfile to your repository.
4. Set up a Jenkins job to use this pipeline.

Step 3: Deploy to Kubernetes

Define your Kubernetes deployment in k8s/deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-app
        image: my-docker-repo/my-app:latest
        ports:
        - containerPort: 8080

Apply the deployment:

kubectl apply -f k8s/deployment.yaml

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Example: Setting Up CI/CD with GitLab

Step 1: Install GitLab Runner on Kubernetes

1. Use Helm to deploy GitLab Runner:helm repo add gitlab https://charts.gitlab.io helm repo update helm install gitlab-runner gitlab/gitlab-runner --namespace gitlab --create-namespace
2. Register the Runner:kubectl exec -it <gitlab-runner-pod> -- gitlab-runner register

Step 2: Create a .gitlab-ci.yml File

stages:
  - build
  - test
  - deploy

build:
  stage: build
  script:
    - docker build -t my-docker-repo/my-app:latest .
    - docker push my-docker-repo/my-app:latest

test:
  stage: test
  script:
    - docker run my-docker-repo/my-app:latest npm test

deploy:
  stage: deploy
  script:
    - kubectl apply -f k8s/deployment.yaml

Step 3: Commit and Push

Commit the .gitlab-ci.yml file to your repository. GitLab will automatically detect and execute the pipeline.

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Best Practices for CI/CD Pipelines in Kubernetes

1. Use Immutable Docker Images: Avoid modifying images after creation.
2. Secure Secrets: Use Kubernetes Secrets to manage sensitive data.
3. Monitor Pipelines: Integrate monitoring tools like Prometheus.
4. Optimize Builds: Use caching mechanisms to speed up builds.
5. Automate Rollbacks: Ensure rollback mechanisms are in place for failed deployments.

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Conclusion

CI/CD pipelines bring automation, consistency, and efficiency to application development and deployment. Integrating tools like Jenkins or GitLab with Kubernetes allows teams to build scalable and reliable workflows for modern applications.

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References

• Kubernetes Documentation
• Jenkins Kubernetes Plugin
• GitLab CI/CD Documentation

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Feedback and Discussion

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