Introduction

🌟 In modern cloud-native environments, ensuring zero-downtime deployments while maintaining robust security is critical. Blue-Green Deployment is a proven strategy that allows teams to switch traffic between different versions of an application seamlessly. Combined with TLS encryption for secure communication, this approach ensures a smooth and secure user experience.
🚀 In this guide, we’ll implement a Blue-Green Deployment in Kubernetes, utilizing Cert-Manager for automated TLS certificate management and Nginx Ingress for traffic routing. By the end of this project, you’ll have a production-ready setup that you can replicate in your own environments.

Tech Stack

🔧 Kubernetes: Cluster orchestration and management.
🔒 Cert-Manager: Automated TLS certificate management.
🌐 Nginx Ingress Controller: Routing HTTP(S) traffic to your services.
📦 Helm (optional): Simplifying deployments.
🛡️ Let's Encrypt: Free TLS certificates for HTTPS.
📡 MetalLB: LoadBalancer for bare-metal Kubernetes clusters.
💻 kubectl: Command-line tool for interacting with Kubernetes.

Prerequisites

✅ Kubernetes Cluster: I will be using MICROK8S on this project on a bare-metal setup with MetalLB for LoadBalancer.
✅ kubectl: Install and configure kubectl to interact with your cluster.
✅ Helm: Install Helm, the Kubernetes package manager, for simplified application deployment and configuration.
✅ Cert-Manager: Ensure Cert-Manager is installed in the cluster for TLS certificate management.
✅ Nginx Ingress Controller: Deploy the Nginx Ingress Controller to handle HTTP(S) traffic routing.
✅ Namespace Configuration: Create separate namespaces or labels for blue and green deployments.
✅ Domain Name: Set up a domain name (or subdomain) terranetes.com pointing to your LoadBalancer IP address. I Used Cloudflare to manage my DNS .
✅ Let's Encrypt Account: Prepare for certificate issuance by having a valid email for Let's Encrypt configuration.
✅ Basic Networking Knowledge: Familiarity with Kubernetes networking concepts, including Ingress and Services.

Architecture

DEPLOYMENTS

Let’s create different namespaces for the project. And also add some environment variables for the project

export CLOUDFLARE_API_KEY="xxxx change your token xxxxxxx"
export EMAIL="[email protected]"

echo $CLOUDFLARE_API_KEY
echo $EMAIL

kubectl create namespace blue-green
kubectl create namespace cert-manager

Deploy Certificate components

• Create Cloudflare API Token Secret for cert-manager.

  # Create Cloudflare API Token Secret for cert-manager
  kubectl create secret generic cloudflare-api-token-cert-manager \
    --namespace cert-manager \
    --from-literal=api-token="$CLOUDFLARE_API_KEY"

  kubectl get secret cloudflare-api-token-cert-manager -n cert-manager -o yaml

• Create a ClusterIssuer with Cloudflare DNS-01 validation.

  apiVersion: cert-manager.io/v1
  kind: ClusterIssuer
  metadata:
    name: letsencrypt-dns01-nginx
  spec:
    acme:
      server: https://acme-v02.api.letsencrypt.org/directory
      email: $EMAIL
      privateKeySecretRef:
        name: letsencrypt-dns01-private-nginx-key
      solvers:
      - dns01:
          cloudflare:
            email: $EMAIL
            apiTokenSecretRef:
              name: cloudflare-api-token-cert-manager
              key: api-token

• Create a Certificate that references the ClusterIssuer letsencrypt-dns01-nginx. I want to create the certificate in blue-green namespace.

  apiVersion: cert-manager.io/v1
  kind: Certificate
  metadata:
    name: blue-green-nginx-cert
    namespace: blue-green
  spec:
    secretName: blue-green-nginx-tls                     # Reference the secret name on encoding secretName value
    duration: 2160h # 90 days
    renewBefore: 360h # 15 days
    isCA: false
    privateKey:
      algorithm: RSA
      encoding: PKCS1
      size: 4096
    issuerRef:
      name: letsencrypt-dns01-nginx
      kind: ClusterIssuer
      group: cert-manager.io
    dnsNames:
      - "blue.terranetes.com"
      - "green.terranetes.com"

Green Environment is my default live environment.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: terranetes-nodegreen
  namespace: blue-green
  labels:
    app: terranetes-nodegreen
    version: green
spec:
  replicas: 3
  selector:
    matchLabels:
      app: terranetes-nodegreen
      version: green
  template:
    metadata:
      labels:
        app: terranetes-nodegreen
        version: green
    spec:
      containers:
      - name: terranetes-nodegreen
        image: georgeezejiofor/terranetes-nodegreen:green-v1
        imagePullPolicy: Always
        ports:
        - containerPort: 3000
        env:
        - name: VERSION
          value: "green"
        - name: HOSTNAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
---
apiVersion: v1
kind: Service
metadata:
  name: terranetes-nodegreen-svc
  namespace: blue-green
spec:
  selector:
    app: terranetes-nodegreen
  ports:
    - protocol: TCP
      port: 80
      targetPort: 3000

Blue Environment is my NEW live environment.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: terranetes-nodeblue
  namespace: blue-green
  labels:
    app: terranetes-nodeblue
    version: blue
spec:
  replicas: 3
  selector:
    matchLabels:
      app: terranetes-nodeblue
      version: blue
  template:
    metadata:
      labels:
        app: terranetes-nodeblue
        version: blue
    spec:
      containers:
      - name: terranetes-nodeblue
        image: georgeezejiofor/terranetes-nodeblue:blue-v1
        imagePullPolicy: Always
        ports:
        - containerPort: 3000
        env:
        - name: VERSION
          value: "blue"
        - name: HOSTNAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
---
apiVersion: v1
kind: Service
metadata:
  name: terranetes-nodeblue-svc
  namespace: blue-green
spec:
  selector:
    app: terranetes-nodeblue
  ports:
    - protocol: TCP
      port: 80
      targetPort: 3000

This services terranetes-nodeblue-svc and terranetes-nodegreen-svc acts as a Router or Switch to different environments.
The services are also deployed as a clusterIP. Hence can only be access within the cluster. I’m going to expose the service from the Loadbalancer of my ingress Controller. Also Update the Ingress resource with TLS configuration.

Deploy Ingress resource to expose both services

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: blue-green-ingress
  namespace: blue-green
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-dns01-nginx
spec:
  ingressClassName: nginx
  tls:
    - hosts:
        - blue.terranetes.com
        - green.terranetes.com
      secretName: blue-green-nginx-tls
  rules:
    - host: blue.terranetes.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: terranetes-nodeblue-svc  
                port:
                  number: 80
    - host: green.terranetes.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: terranetes-nodegreen-svc  
                port:
                  number: 80
---

Initial Traffic Routing

Currently, the traffic is split between blue.terranetes.com (blue app) and green.terranetes.com (green app). This setup routes users based on the hostname. Now let’s switching traffic from green environment (Live) to blue environment (New). And we are doing this switching on ingress resource. This is acting as out router .

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: blue-green-ingress
  namespace: blue-green
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-dns01-nginx
spec:
  ingressClassName: nginx
  tls:
    - hosts:
        - blue.terranetes.com
        - green.terranetes.com
      secretName: blue-green-nginx-tls
  rules:
    - host: blue.terranetes.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: terranetes-nodeblue-svc
                port:
                  number: 80
    - host: green.terranetes.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: terranetes-nodeblue-svc   # update blue svc here
                port:
                  number: 80

You will notice that even green.terranetes.com url will access (blue app).

https://blue.terranetes.com/

https://green.terranetes.com/

We just switch the green app users from green environment to blue environment we can easily rollback with this strategy by switching the service back to green svc on green.terranetes.com .

Rolling Back the Switch

You can roll back by modifying the Ingress again to restore the original routing:

blue.terranetes.com -> blue app

green.terranetes.com -> green app

Optional: Weighted Traffic Splitting

If you want to gradually switch users from green to blue (or vice versa), consider implementing canary deployment or weighted routing using tools like:

NGINX annotations (if supported).

Istio or Traefik for advanced traffic management.

This allows for:

Gradual routing (e.g., 80% green, 20% blue).

Monitoring the behavior of users before full migration.

Conclusion 🎉

Through this guide, we’ve successfully implemented a Blue-Green Deployment strategy on Kubernetes with robust TLS encryption, utilizing Cert-Manager and Nginx Ingress. This architecture ensures zero-downtime deployments, seamless traffic switching, and enhanced security, making it a reliable choice for production environments.

By switching users between green and blue environments effortlessly, we’ve demonstrated the power of dynamic traffic management. Whether it’s for releasing new features or mitigating issues with instant rollbacks, this approach minimizes risk and enhances user experience.

Additionally, the option to incorporate weighted traffic splitting or canary deployments provides further flexibility for gradual rollouts, enabling better control and monitoring during transitions.

Key Takeaways 🗝️

Ease of Switching: ✨ Modify the Ingress resource to direct traffic instantly.

Enhanced Security: 🔒 Automated TLS certificates ensure secure communication.

Rollback Ready: 🔄 Revert traffic with minimal effort.

Scalability: 📈 Extend the setup to support more complex routing patterns like weighted traffic.

With this setup, you’re equipped to deploy applications confidently, ensuring both reliability and user satisfaction. Ready to try this out in your environment? 🚀

Happy Deploying! 🌟