🚀 Canary Deployment in Kubernetes (Beginner-Friendly Project)

This project demonstrates a Canary Deployment in Kubernetes without using a service mesh.

A canary deployment lets you release a new version of your application to a small percentage of users before rolling it out to everyone.

📌 What is Canary Deployment?

A canary deployment is a rollout strategy where:

• Most users get the stable (old) version
• A few users get the new (canary) version

If everything works well → promote the canary If something breaks → roll back quickly

🛠 Technologies Used

• Node.js (simple backend app)
• Docker (containerization)
• Minikube (local Kubernetes cluster)
• kubectl (Kubernetes CLI)
• YAML (Kubernetes manifests)

📁 Project Structure

Repository root:

• app_v1.js # Stable application (v1)
• app_v2.js # Canary application (v2)
• Dockerfile-v1 # Dockerfile for v1
• Dockerfile-v2 # Dockerfile for v2
• deployment_v1.yaml # Stable Kubernetes deployment (v1)
• deployment_v2.yaml # Canary Kubernetes deployment (v2)
• services.yaml # Kubernetes Service
• package.json # Node.js dependencies
• README.md # This file
• screenshots/ # Proof and screenshots (optional)

⚙️ Step 1 — Create Application Files

Version 1 (Stable) — app_v1.js

const express = require('express')
const app = express()
app.get("/",(req,res)=>{
  res.send("It is the Stable Version")
})
app.listen(8080, ()=>console.log("Stable V1 is running"))

Version 2 (Canary) — app_v2.js

const express = require('express')
const app = express()
app.get("/",(req,res)=>{
  res.send("It is the canary Version")
})
app.listen(8080, ()=> console.log("Canary V2 is running"))

�� Step 2 — Dockerfiles

Dockerfile-v1

FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY app_v1.js .
EXPOSE 8080
CMD ["node","app_v1.js"]

Dockerfile-v2

FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY app_v2.js .
EXPOSE 8080
CMD ["node","app_v2.js"]

📦 Step 3 — Build & Push Docker Images

Run:

docker build -f Dockerfile-v1 -t <yourhub>/canary-app:v1 .
docker push <yourhub>/canary-app:v1

docker build -f Dockerfile-v2 -t <yourhub>/canary-app:v2 .
docker push <yourhub>/canary-app:v2

(Replace <yourhub> with your Docker Hub username or registry.)

☸️ Step 4 — Kubernetes Deployments

deployment_v1.yaml (Stable)

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-v1
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: app
        image: <yourhub>/canary-app:v1
        ports:
        - containerPort: 8080

deployment_v2.yaml (Canary)

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-v2
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: app
        image: <yourhub>/canary-app:v2
        ports:
        - containerPort: 8080

🌐 Step 5 — Kubernetes Service

services.yaml

apiVersion: v1
kind: Service
metadata:
  name: myapp-service
spec:
  type: NodePort
  selector:
    app: myapp
  ports:
  - port: 80
    targetPort: 8080
    nodePort: 30080

🚀 Step 6 — Deploy to Kubernetes

kubectl apply -f deployment_v1.yaml
kubectl apply -f deployment_v2.yaml
kubectl apply -f services.yaml

Check pods:

kubectl get pods

You should see:

• 3 pods → v1 (stable)
• 1 pod → v2 (canary)

🌍 Step 7 — Access the Application

minikube service myapp-service --url

Open the generated URL in your browser. Refresh multiple times — you should mostly see the stable version and occasionally the canary.

🔄 Step 8 — Rollback Canary Version

If the canary has issues:

kubectl delete deployment app-v2

Now 100% of traffic goes to the stable version (v1).

⬆️ Step 9 — Promote Canary → Stable

If the canary is successful:

kubectl set image deployment/app-v1 app=<yourhub>/canary-app:v2
kubectl delete deployment app-v2

Now 100% of users receive version v2.

📸 Screenshots

Below are the screenshots (files under screenshots/). If you don't have them yet, add PNGs with these names and they will render.

Output of kubectl get pods

Output of kubectl describe svc myapp-service

Output of minikube service myapp-service --url

Output of while true; do curl <url>; echo; sleep 0.5; done

Output of Rollback

Output of Promote

Docker images pushed

🎯 Conclusion

This project demonstrates:

• Canary deployment
• Traffic splitting without a service mesh
• Multi-version Kubernetes deployment
• Rollback and promotion strategies

✨ Author

Dhruv Sharma B.Tech — JK Lakshmipat University