RollingUpdate(滾動更新)

當image更新版本之後，可以利用RollingUpdate替換pod裡container的image版本，進行不中斷服務的更新。
deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deployment-demo
  labels:
    app: ubuntu
spec:
  replicas: 2
  selector:
    matchLabels:
      app: ubuntu
  template:
    metadata:
      labels:
        app: ubuntu
    spec:
      containers:
      - name: ubuntu
        image: ubuntu:20.04
        args: [bash, -c, 'for ((i = 0; ; i++)); do echo "$i: $(date)"; sleep 100; done']

部屬Deployment之後，再查看pod

root@master:/# kubectl apply -f deployment.yaml 
deployment.apps/deployment-demo created

root@master:/# kubectl get pod
NAME                              READY   STATUS    RESTARTS   AGE
deployment-demo-68d5b9f46-wt5gr   1/1     Running   0          4s
deployment-demo-68d5b9f46-z8hbr   1/1     Running   0          4s

進入deployment-demo-68d5b9f46-wt5gr，並查看當前ubuntu版本

root@master:/# kubectl exec -ti deployment-demo-68d5b9f46-wt5gr -- bash

root@deployment-demo-68d5b9f46-wt5gr:/# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.4 LTS"

退出pod之後，更換image版本

root@master:/test# kubectl set image deployment/deployment-demo ubuntu=ubuntu:18.04 --record
deployment.apps/deployment-demo image updated

再次查看pod並進入到pod內查看ubuntu版本

root@master:/# kubectl get pod
NAME                              READY   STATUS    RESTARTS   AGE
deployment-demo-94fc48665-mvtz2   1/1     Running       0      68s
deployment-demo-94fc48665-xq8b9   1/1     Running       0      65s

root@master:/# kubectl exec -ti deployment-demo-94fc48665-mvtz2 -- bash

root@deployment-demo-94fc48665-mvtz2:/# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.6 LTS"

查看更新紀錄

root@master:/# kubectl rollout history deployment deployment-demo
deployment.apps/deployment-demo 
REVISION  CHANGE-CAUSE
1         <none>
2         kubectl set image deployment/deployment-demo ubuntu=ubuntu:18.04 --record=true

RollBack(回滾)

當更新後發現系統有問題時，可以利用回滾功能把系統回復。你可以回到上一版本或回到指定版本

回到上一版本

kubectl rollout undo deployment [name]

回到指定版本

kubectl rollout undo deployment [name] --to-revision=[version]

假如我要回到第一版的話:

root@master:/# kubectl rollout undo deployment deployment-demo --to-revision=1
deployment.apps/deployment-demo rolled back

root@master:/# kubectl get pod
NAME                              READY   STATUS        RESTARTS   AGE
deployment-demo-68d5b9f46-rwgzr   1/1     Running       0          12s
deployment-demo-68d5b9f46-skqcq   1/1     Running       0          9s
deployment-demo-94fc48665-mvtz2   1/1     Terminating   0          17m
deployment-demo-94fc48665-xq8b9   1/1     Terminating   0          17m

root@master:/# kubectl exec -ti deployment-demo-68d5b9f46-rwgzr -- bash

root@deployment-demo-68d5b9f46-rwgzr:/# cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.4 LTS"