rolling_updates.md

Rolling updates and Rollbacks

• Documentation

• https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#updating-a-deployment

• https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#rolling-back-a-deployment

Here is a sample deployment you can use to practice rolling updates and rollbacks.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: rolling-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.1
        ports:
        - containerPort: 80

Perform a rolling update.

kubectl set image deployment/rolling-deployment nginx=nginx:1.7.9 --record

Explore the rollout history of the deployment.

kubectl rollout history deployment/rolling-deployment

kubectl rollout history deployment/rolling-deployment --revision=2

You can roll back to the previous revision like so.

kubectl rollout undo deployment/rolling-deployment

You can also roll back to a specific earlier revision by providing the revision number.

kubectl rollout undo deployment/rolling-deployment --to-revision=1

You can also control how rolling updates are performed by setting maxSurge and maxUnavailable in the deployment spec:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: rolling-deployment
spec:
  strategy:
    rollingUpdate:
      maxSurge: 3
      maxUnavailable: 2
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.1
        ports:
        - containerPort: 80