Category: Kubernetes Tip

bookmark_borderKubernetes Update Strategies

Posted on by Jay Jo
  • Recreate: terminate the old version and release the new one
    • Pro: application state entirely renewed
    • Cons: downtime that depends on both shutdown and boot duration of the application
  • Rolling update: New pods are added gradually, and old pods are terminated gradually.
    • Pro:
      • version is slowly released across instances
      • convenient for stateful applications that can handle rebalancing of the data
    • Cons:
      • rollout/rollback can take time
      • supporting multiple APIs is hard
      • no control over traffic

Recreate

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.14.2
          ports:
            - containerPort: 80
kubectl apply -f recreate-deployment.yaml
kubectl rollout status deployment/nginx-deployment
kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record

Rolling Update

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 4      
      maxUnavailable: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.14.2
          ports:
            - containerPort: 80
kubectl apply -f recreate-deployment.yaml
kubectl rollout status deployment/nginx-deployment
kubectl set image deployment/nginx-deployment nginx=nginx:1.16.1 --record

-. maxSurge: The number of pods that can be created above the desired amount of pods during an update

-. maxUnavailable: The number of pods that can be unavailable during the update process

  • blue/green: release a new version alongside the old version then switch traffic
  • canary: release a new version to a subset of users, then proceed to a full rollout
ANOTE.DEV