Scenario

Your team has a stable deployment app-v1 running in namespace canary. They want to test a new version (v2) with approximately 1/3 of traffic going to v2 and 2/3 remaining on v1.

Task

Implement canary traffic splitting between both versions using only native Kubernetes resources.

A reference deployment file is available at /home/interview/deployment.yaml.

Step 1: Check existing deployment

kubectl get deployment app-v1 -n canary -o yaml
cat /home/interview/deployment.yaml

Note that app-v1 pods already have label app=my-app.

Step 2: Create canary deployment (v2) with 1 replica

Copy and modify the reference file:

cp /home/interview/deployment.yaml /home/interview/app-v2.yaml

Edit app-v2.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-v2
  namespace: canary
spec:
  replicas: 1
  selector:
    matchLabels:
      deployment: app-v2
  template:
    metadata:
      labels:
        app: my-app          # Same common label as v1
        version: v2
        deployment: app-v2
    spec:
      containers:
      - name: nginx
        image: nginx:1.25

kubectl apply -f /home/interview/app-v2.yaml

Step 3: Create service that selects the common label

kubectl create service clusterip my-app-svc -n canary --tcp=80:80 --dry-run=client -o yaml > /home/interview/svc.yaml

Edit /home/interview/svc.yaml to use the common selector:

apiVersion: v1
kind: Service
metadata:
  name: my-app-svc
  namespace: canary
spec:
  selector:
    app: my-app           # Selects pods from BOTH deployments
  ports:
  - port: 80
    targetPort: 80

kubectl apply -f /home/interview/svc.yaml

Step 4: Verify

kubectl get pods -n canary -l app=my-app -o wide
kubectl get endpoints my-app-svc -n canary

The endpoints should show 3 pod IPs (2 from v1, 1 from v2).