How to Build a Blue-Green Deployment Pipeline

Modern software development demands zero downtime, continuous delivery, and seamless updates. However, deploying new versions of an application often introduces risks—downtime, errors, or broken features that impact users. That’s where blue-green deployment comes in. This strategy allows you to release updates with minimal risk and instant rollback capabilities.

In this blog, we’ll explore what blue-green deployment is, how it works, and provide a step-by-step guide on how to build a blue-green deployment pipeline using modern DevOps tools and cloud platforms like AWS, Kubernetes, and Jenkins.

What Is Blue-Green Deployment?

Blue-Green Deployment is a release management strategy that reduces downtime and risk during deployments. It involves maintaining two identical environments:

• Blue Environment: The current, live version serving users.

• Green Environment: The new version, deployed and tested in parallel.

When the new version (green) is ready and verified, the load balancer redirects all traffic from blue to green. If something goes wrong, the switch can be instantly reversed.

Key Benefits of Blue-Green Deployment

• Zero Downtime: Users never experience interruptions during updates.

• Instant Rollback: Quickly revert to the old version if a bug appears.

• Reduced Risk: Test new releases in a production-like environment.

• Simplified Testing: You can run end-to-end validation before switching traffic.

How Blue-Green Deployment Works

1. Prepare Two Identical Environments — both blue (live) and green (staging).

2. Deploy the New Version to the green environment.

3. Run Tests and Validations to ensure stability and performance.

4. Switch Traffic to the green environment once validated.

5. Keep the Blue Environment Idle for quick rollback if issues arise.

This process ensures a seamless user experience, even during critical application upgrades.

When to Use Blue-Green Deployment

Blue-green deployment is ideal for:

• Microservices architectures with containerized applications.

• Cloud-native environments (AWS, Azure, GCP).

• Mission-critical systems that cannot afford downtime.

• CI/CD pipelines that require quick and safe rollouts.

However, it may not be necessary for small, low-traffic projects due to additional infrastructure costs.

Core Components of a Blue-Green Deployment Pipeline

Before building your pipeline, let’s understand the essential components:

1. Version Control System (VCS)

Tools like GitHub or GitLab store source code and track changes.

2. Continuous Integration (CI)

A CI server (e.g., Jenkins, GitHub Actions, or GitLab CI) automates testing and builds.

3. Continuous Deployment (CD)

CD tools automate deployment to staging or production environments.

4. Load Balancer

A load balancer (like AWS Elastic Load Balancer or NGINX) routes traffic between blue and green environments.

5. Monitoring and Rollback System

Monitoring tools like Prometheus, Grafana, or AWS CloudWatch help detect errors and revert quickly if necessary.

Step-by-Step Guide to Building a Blue-Green Deployment Pipeline

Let’s go through the process of setting up a blue-green pipeline using AWS and Jenkins as an example.

Step 1: Set Up Two Identical Environments

Create two environments:

• Blue: Your existing production environment.

• Green: A clone of blue where the new version will be deployed.

You can host both on AWS EC2 instances, ECS (Elastic Container Service), or Kubernetes clusters.

Step 2: Configure a Load Balancer

Use AWS Elastic Load Balancer (ELB) or NGINX to direct user traffic.

For instance:

• Blue environment — currently receiving traffic.

• Green environment — isolated for deployment and testing.

When the green version passes testing, the load balancer switches routing to it.

Step 3: Automate Build and Testing

In Jenkins, configure a CI pipeline to:

1. Pull the latest code from GitHub.

2. Run automated tests.

3. Build a Docker image using a Dockerfile.

4. Push the image to a registry (like Amazon ECR or Docker Hub).

Example Jenkinsfile snippet:

pipeline {
  agent any
  stages {
    stage('Build') {
      steps {
        sh 'docker build -t myapp:latest .'
      }
    }
    stage('Test') {
      steps {
        sh 'npm test'
      }
    }
    stage('Push Image') {
      steps {
        sh 'docker tag myapp:latest myrepo/myapp:latest'
        sh 'docker push myrepo/myapp:latest'
      }
    }
  }
}

Step 4: Deploy the New Version to the Green Environment

Once the build is complete, Jenkins automatically deploys the new version to the green environment.

If you’re using AWS ECS or EKS, deployment commands may look like this:

aws ecs update-service --cluster MyCluster --service GreenService --force-new-deployment

Step 5: Run Integration and Smoke Tests

Before switching traffic, ensure everything works as expected in the green environment. Run tests such as:

• API response validation.

• Frontend UI tests using Selenium or Cypress.

• Load and performance testing.

Step 6: Switch Traffic from Blue to Green

After verifying the new version, update the load balancer configuration:

• Redirect all incoming requests to the green environment.

• Keep the blue environment running in the background temporarily.

In AWS, this can be achieved via:

aws elbv2 modify-listener --listener-arn <listener-arn> --default-actions Type=forward,TargetGroupArn=<green-target-group-arn>

Step 7: Monitor the Green Environment

Monitor application performance using tools like:

• AWS CloudWatch

• Grafana + Prometheus

• Datadog

If errors or performance issues arise, roll back by switching the load balancer to the blue environment.

Step 8: Decommission the Old Environment

Once the green deployment proves stable, shut down or repurpose the blue environment.

This step conserves resources and ensures that future deployments can reuse the blue slot for the next version.

Example: Blue-Green Deployment with Kubernetes

For Kubernetes users, the process is quite similar but uses Ingress controllers for traffic management.

Define two deployments (blue and green) and switch traffic via service labels or annotations:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-green
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
      color: green
  template:
    metadata:
      labels:
        app: myapp
        color: green
    spec:
      containers:
        - name: myapp
          image: myrepo/myapp:v2
          ports:
            - containerPort: 80

You can then update the Kubernetes service to point from blue to green:

kubectl patch service myapp-service -p '{"spec":{"selector":{"app":"myapp","color":"green"}}}'

This instantly redirects traffic to the green pods without downtime.

Best Practices for Blue-Green Deployments

1. Use Immutable Infrastructure

Each deployment should be treated as a fresh environment — avoid modifying existing infrastructure.

2. Automate Everything

Use CI/CD pipelines to handle code builds, deployments, and rollbacks automatically.

3. Test Thoroughly Before Switching

Validate your application using functional and performance tests before routing traffic.

4. Monitor Continuously

Track system health metrics (CPU, memory, response times) after switching traffic.

5. Keep Rollback Simple

Always maintain the blue environment for immediate rollback if needed.

6. Optimize for Cost

If running both environments permanently is costly, consider scaling one down when inactive.

Advantages of Blue-Green Deployment

• High Availability: Ensures uptime even during major releases.

• Risk-Free Upgrades: Easily revert if bugs are discovered post-deployment.

• Consistent Testing: Identical infrastructure makes validation accurate.

• Improved User Experience: Users don’t notice when the switch happens.

Challenges and Considerations

• Infrastructure Cost: Maintaining two environments doubles resource usage.

• Database Synchronization: Changes to database schemas must be handled carefully.

• Configuration Management: Both environments must remain identical for reliable switching.

Conclusion

Building a blue-green deployment pipeline is one of the most reliable strategies for achieving zero-downtime deployments and continuous delivery. By maintaining two mirrored environments and seamlessly switching traffic, teams can confidently release updates without disrupting users.

With tools like Jenkins, Kubernetes, and AWS Elastic Load Balancer, implementing blue-green deployments is easier than ever. As automation and CI/CD practices evolve, mastering this technique ensures smoother, safer, and faster deployments in 2025 and beyond.