k8s中的pod更新策略
阿新 • • 發佈：2021-07-17
StatefulSet（有狀態集，縮寫為sts）常用於部署有狀態的且需要有序啟動的應用程式，比如在進行SpringCloud專案容器化時，Eureka的部署是比較適合用StatefulSet部署方式的，可以給每個Eureka例項建立一個唯一且固定的識別符號，並且每個Eureka例項無需配置多餘的Service，其餘Spring Boot應用可以直接通過Eureka的Headless Service即可進行註冊。 Eureka的statefulset的資源名稱是 eureka，eureka-0 eureka-1 eureka-2 Service：headless service，沒有ClusterIP [每個] eureka-svc Eureka-0.eureka-svc.NAMESPACE_NAME eureka-1.eureka-svc … 連線 eureka的資源名稱為：eureka
statefullset示例
apiVersion: v1 kind: Service metadata: name: nginx labels: app: nginx spec: ports: - port: 80 name: web clusterIP: None selector: app: nginx --- apiVersion: apps/v1 kind: StatefulSet metadata: name: web spec: serviceName: "nginx" replicas: 2 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx ports: - containerPort: 80 name: web [root@k8s-master01 statefullset]# kubectl create -f statefullset.yaml service/nginx created statefulset.apps/web created #擴容： replicas: 2 #[定義副本集數量] [root@k8s-master01 statefullset]# kubectl get pod web-0 1/1 Running 0 1m web-1 1/1 Running 0 1m #命令擴容 [root@k8s-master01 statefullset]# kubectl scale --replicas=3 sts web statefulset.apps/web scaled #檢查擴容 [root@k8s-master01 statefullset]# kubectl get pod NAME READY STATUS RESTARTS AGE web-0 1/1 Running 0 15m web-1 1/1 Running 0 12m web-2 1/1 Running 0 35s #檢查擴容流程： [root@k8s-master01 ~]# kubectl scale --replicas=5 sts web statefulset.apps/web scaled [root@k8s-master01 ~]# kubectl get pod -l app=nginx -w NAME READY STATUS RESTARTS AGE nginx-68db656dd8-cc4jv 1/1 Running 0 36h nginx-68db656dd8-hvj8x 1/1 Running 0 36h web-0 1/1 Running 0 18h web-1 1/1 Running 0 18h web-2 0/1 Pending 0 0s web-2 0/1 Pending 0 0s web-2 0/1 ContainerCreating 0 0s web-2 1/1 Running 0 18s web-3 0/1 Pending 0 0s web-3 0/1 Pending 0 0s web-3 0/1 ContainerCreating 0 0s web-3 1/1 Running 0 18s web-4 0/1 Pending 0 0s web-4 0/1 Pending 0 0s web-4 0/1 ContainerCreating 0 0s web-4 1/1 Running 0 17s
statefulset 更新策略
#預設更新策略： updateStrategy: rollingUpdate: partition: 0 # 設定為1 一次更新一個，如果設定為 0 則是隨機更新 type: RollingUpdate #--- statefulset預設更新策略 滾動更新，有一個更新失敗就不會繼續更新，deployment是隨機更新模式 statefulset更新策略： 1. RollingUpdate 滾動更新 [從下往上更新，倒序更新] 2. OnDelete 手動更新 [需要刪除一個pod才會觸發更新策略]
預設更新策略RollingUpdate示例：
執行命令: kubectl edit sts web
找到:
containers:
- image: nginx
改為:
containers:
- image: nginx:1.15.2
# 檢視更新過程：
[root@k8s-master01 ~]# kubectl get pod -l app=nginx -w
NAME READY STATUS RESTARTS AGE
web-0 1/1 Running 0 20h
web-1 1/1 Running 0 20h
web-2 1/1 Running 0 89m
web-2 1/1 Terminating 0 90m
web-2 0/1 Terminating 0 90m
web-2 0/1 Terminating 0 90m
web-2 0/1 Terminating 0 90m
web-2 0/1 Pending 0 0s
web-2 0/1 Pending 0 0s
web-2 0/1 ContainerCreating 0 0s
web-2 1/1 Running 0 19s
web-1 1/1 Terminating 0 20h
web-1 0/1 Terminating 0 20h
web-1 0/1 Terminating 0 20h
web-1 0/1 Terminating 0 20h
web-1 0/1 Pending 0 0s
web-1 0/1 Pending 0 0s
web-1 0/1 ContainerCreating 0 0s
web-1 1/1 Running 0 20s
web-0 1/1 Terminating 0 20h
web-0 0/1 Terminating 0 20h
web-0 0/1 Terminating 0 20h
web-0 0/1 Terminating 0 20h
web-0 0/1 Pending 0 0s
web-0 0/1 Pending 0 0s
web-0 0/1 ContainerCreating 0 0s
web-0 1/1 Running 0 19s
# 檢視更新結果：
[root@k8s-master01 ~]# kubectl get pod -l app=nginx
NAME READY STATUS RESTARTS AGE
web-0 1/1 Running 0 59s
web-1 1/1 Running 0 88s
web-2 1/1 Running 0 118s
# 驗證結果：
[root@k8s-master01 ~]# kubectl exec -it web-0 -- sh
# nginx -v
nginx version: nginx/1.15.2
OnDelete策略示例：
# 修改為 OnDelete 策略
# kubectl edit sts web
找到:
updateStrategy:
rollingUpdate:
partition: 0
type: RollingUpdate
改為:
updateStrategy:
type: OnDelete
# 修改映象版本來檢視 是否此策略會更新版本
image: nginx
#改為：
image: nginx:1.15.3
#儲存 [刪除 rollingUpdate: 與 partition: 0 並且將 type: RollingUpdate 改為 type: OnDelete ]
#檢查：
[root@k8s-master01 ~]# kubectl get pod |grep web
NAME READY STATUS RESTARTS AGE
web-0 1/1 Running 0 6m58s
web-1 1/1 Running 0 7m17s # <-- 並未更新
web-2 1/1 Running 0 7m48s
#再次修改映象版本並刪除其中一個pod：
[root@k8s-master01 ~]# kubectl edit sts web #把 nginx:1.15.3 改為 nginx:1.15.2
statefulset.apps/web edited
[root@k8s-master01 statefullset]# kubectl delete pod web-1
pod "web-1" deleted
# 檢查刪除的pod更新狀態：
[root@k8s-master01 statefullset]# kubectl get pod web-1 -o yaml|grep image
- image: nginx:1.15.3
imagePullPolicy: Always
image: nginx:1.15.3
imageID: docker-pullable://nginx@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
# 檢查未刪除的pod版本：
[root@k8s-master01 statefullset]# kubectl get pod web-0 -o yaml|grep image
- image: nginx
imagePullPolicy: Always
image: nginx:latest
imageID: docker-pullable://nginx@sha256:353c20f74d9b6aee359f30e8e4f69c3d7eaea2f610681c4a95849a2fd7c497f9
# 再刪除這個未刪除的版本檢查刪除後是否會更新，剛刪除的web-1 現在刪除web-0：
[root@k8s-master01 statefullset]# kubectl delete pod web-0
pod "web-0" deleted
#檢查刪除後的web-0 是否更新了版本
[root@k8s-master01 statefullset]# kubectl get pod web-0 -o yaml|grep image
- image: nginx:1.15.3
imagePullPolicy: Always
image: nginx:1.15.3 # -- 確定已經更新了版本
imageID: docker-pullable://nginx@sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3
這就是Ondelete的更新策略
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