Canary Deployment

Requirements

Make sure you have Nginx Ingress deployed on your cluster:

https://kubernetes.github.io/ingress-nginx/deploy/

Deploy app v1

kubectl create -f - <<EOF

apiVersion: v1
kind: Service
metadata:
  name: my-app-v1
  labels:
    app: my-app
spec:
  ports:
  - name: http
    port: 80
    targetPort: http
  selector:
    app: my-app
    version: v1.0.0
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app-v1
  labels:
    app: my-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: my-app
      version: v1.0.0
  template:
    metadata:
      labels:
        app: my-app
        version: v1.0.0
      annotations:
        prometheus.io/scrape: "true"
        prometheus.io/port: "9101"
    spec:
      containers:
      - name: my-app
        image: containersol/k8s-deployment-strategies
        ports:
        - name: http
          containerPort: 8080
        - name: probe
          containerPort: 8086
        env:
        - name: VERSION
          value: v1.0.0
        livenessProbe:
          httpGet:
            path: /live
            port: probe
          initialDelaySeconds: 5
          periodSeconds: 5
        readinessProbe:
          httpGet:
            path: /ready
            port: probe
          periodSeconds: 5

EOF

Deploy ingress for app v1

kubectl create -f - <<EOF

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: my-app
  labels:
    app: my-app
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: my-app.com
    http:
      paths:
      - backend:
          serviceName: my-app-v1
          servicePort: 80

EOF

Deploy app v2

kubectl create -f - <<EOF

apiVersion: v1
kind: Service
metadata:
  name: my-app-v2
  labels:
    app: my-app
spec:
  ports:
  - name: http
    port: 80
    targetPort: http
  selector:
    app: my-app
    version: v2.0.0
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app-v2
  labels:
    app: my-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: my-app
      version: v2.0.0
  template:
    metadata:
      labels:
        app: my-app
        version: v2.0.0
      annotations:
        prometheus.io/scrape: "true"
        prometheus.io/port: "9101"
    spec:
      containers:
      - name: my-app
        image: containersol/k8s-deployment-strategies
        ports:
        - name: http
          containerPort: 8080
        - name: probe
          containerPort: 8086
        env:
        - name: VERSION
          value: v2.0.0
        livenessProbe:
          httpGet:
            path: /live
            port: probe
          initialDelaySeconds: 5
          periodSeconds: 5
        readinessProbe:
          httpGet:
            path: /ready
            port: probe
          periodSeconds: 5

EOF

Deploy ingress canary for app v2

kubectl create -f - <<EOF

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: my-app-canary
  labels:
    app: my-app
  annotations:
    kubernetes.io/ingress.class: "nginx"

    # Enable canary and send 10% of traffic to version 2
    nginx.ingress.kubernetes.io/canary: "true"
    nginx.ingress.kubernetes.io/canary-weight: "10"
spec:
  rules:
  - host: my-app.com
    http:
      paths:
      - backend:
          serviceName: my-app-v2
          servicePort: 80

EOF

Note the following annotations:

nginx.ingress.kubernetes.io/canary: "true"
nginx.ingress.kubernetes.io/canary-weight: "10"

They ensure only 10% of the traffic will be redirected to this host.

To test run the following command:

while sleep 0.1; do curl "PUT-YOUR-NGINX-INGRESS-IP-HERE" -H "Host: my-app.com"; done

Roll out ingress for app v2

First, delete the ingress canary:

kubectl delete ingress my-app-canary

Then roll out the change.

kubectl create -f - <<EOF

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: my-app
  labels:
    app: my-app
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: my-app.com
    http:
      paths:
      - backend:
          serviceName: my-app-v2
          servicePort: 80

EOF

References

https://medium.com/google-cloud/kubernetes-canary-deployments-for-mere-mortals-13728ce032fe