Kubernetes Rolling Upgrade

Kubernetes Rolling Upgrade (Rollout&Rollback)

Thanks for these blogs

https://tachingchen.com/tw/blog/Kubernetes-Rolling-Update-with-Deployment/ https://www.linux.com/learn/rolling-updates-and-rollbacks-using-kubernetes-deployments

Yaml file

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginxstor
spec:
  #serviceName: "nginxstor"
  replicas: 2
  template:
    metadata:
      labels:
        app: nginxstor
      annotations:
        pod.alpha.kubernetes.io/initialized: "true"
    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 1
            podAffinityTerm:
              labelSelector:
                matchExpressions:
                - key: app
                  operator: In
                  values:
                  - nginxstor
              topologyKey: kubernetes.io/hostname
      containers:
      - name: nginxstor
        image: 192.168.51.130:5000/uwebserverv6
        ports:
          - containerPort: 8000
  minReadySeconds: 5
  strategy:
    # indicate which strategy we want for rolling update
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1

Adding rolling strategy strategy for rolling upgrade.

  minReadySeconds: 5
  strategy:
    # indicate which strategy we want for rolling update
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1

Sleep minReadySecond after container's daemon running and it then start another container.

Rollout (upgrade)

kubectl set image deployment nginxstor nginxstor=192.168.51.130:5000/uwebserverv7 --record

It will start rolling upgrade now

There are several ways to upgrade container, but I prefer this way since with less dependency.

--record is notify kubernetes to record the history, and you will see it later.

To check the status

kubectl rollout status deployment nginxstor

Rollback (downgrade)

To check the version

kubectl rollout history deployment nginxstor

deployments "nginxstor"
REVISION    CHANGE-CAUSE
1       <none>
2       kubectl set image deployment nginxstor nginxstor=192.168.51.130:5000/uwebserverv7 --record=true

Let's go back to revision 1

kubectl rollout undo deployment nginxstor --to-revision=1

Try it, it works amazingly.