Canary deployments in Kubernetes - Mini Project: Build & Apply

Canary Deployments with Kubernetes

📖 Scenario: You are working as a DevOps engineer for a web application team. Your team wants to release a new version of the app safely by gradually sending a small portion of user traffic to the new version first. This approach is called a canary deployment. It helps catch issues early without affecting all users.

🎯 Goal: Build a simple Kubernetes setup that deploys two versions of an app: the stable version and the canary version. Then configure a service to split traffic between them, sending 10% of traffic to the canary version and 90% to the stable version.

📋 What You'll Learn

Create a Deployment for the stable app version with 3 replicas

Create a Deployment for the canary app version with 1 replica

Create a Service that routes 90% traffic to stable and 10% to canary using labels

Print the final Service YAML to verify the traffic split

💡 Why This Matters

🌍 Real World

Canary deployments are used in production to reduce risk when releasing new software versions by gradually shifting user traffic.

💼 Career

DevOps engineers and site reliability engineers use canary deployments to improve software release safety and reliability.

1

Create the stable Deployment

Create a Kubernetes Deployment named app-stable with 3 replicas. Use the container image nginx:1.19. Add the label version: stable to the pod template metadata.

Kubernetes

# Create the stable Deployment with 3 replicas and label version: stable

Need a hint?

Use replicas: 3 and add version: stable label under template.metadata.labels.

2

Create the canary Deployment

Add a new Deployment named app-canary with 1 replica. Use the container image nginx:1.20. Add the label version: canary to the pod template metadata.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-stable
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
      version: stable
  template:
    metadata:
      labels:
        app: myapp
        version: stable
    spec:
      containers:
      - name: nginx
        image: nginx:1.19

# Add the canary Deployment with 1 replica and label version: canary

Need a hint?

Use replicas: 1 and label the pods with version: canary.

3

Create the Service with traffic split

Create a Kubernetes Service named app-service of type ClusterIP. It should select pods with label app: myapp. Use two selectors with weights to split traffic: 90% to pods with label version: stable and 10% to pods with label version: canary. Use spec.selector and spec.traffic fields accordingly.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-stable
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
      version: stable
  template:
    metadata:
      labels:
        app: myapp
        version: stable
    spec:
      containers:
      - name: nginx
        image: nginx:1.19
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-canary
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
      version: canary
  template:
    metadata:
      labels:
        app: myapp
        version: canary
    spec:
      containers:
      - name: nginx
        image: nginx:1.20

# Create the Service named app-service with traffic split 90% stable and 10% canary

Need a hint?

Use spec.traffic with weight and podSelector.matchLabels to split traffic.

4

Print the final Service YAML

Print the full YAML of the app-service to verify the traffic split configuration.

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-stable
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
      version: stable
  template:
    metadata:
      labels:
        app: myapp
        version: stable
    spec:
      containers:
      - name: nginx
        image: nginx:1.19
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-canary
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
      version: canary
  template:
    metadata:
      labels:
        app: myapp
        version: canary
    spec:
      containers:
      - name: nginx
        image: nginx:1.20
---
apiVersion: v1
kind: Service
metadata:
  name: app-service
spec:
  type: ClusterIP
  selector:
    app: myapp
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  traffic:
  - weight: 90
    podSelector:
      matchLabels:
        version: stable
  - weight: 10
    podSelector:
      matchLabels:
        version: canary

# Print the app-service YAML below

Need a hint?

Use a print statement to output the Service YAML exactly as configured.