istio kiali 親和性排程
一、節點排程
在開始 kiali 親和性排程之前,先演示一個簡單的例子介紹 pod 選擇排程到指定 node:
節點打標
使用命令檢視當前所有 k8s 節點:
[root@k8s-master ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION k8s-master Ready master 5h11m v1.18.1 k8s-node01 Ready <none> 5h8m v1.18.1
現在給 k8s-w-206 這個節點打上一個標籤,標籤內容為 name: xiao,命令如下:
kubectl label node k8s-node01 name=xiao
編寫 pod
編寫 pod 資原始檔flaskapp-deployment.yaml,檔案中使用 nodeSelector 指定該 pod 要排程到 k8s-node01節點之上
apiVersion: apps/v1 kind: Deployment metadata: name: flaskapp-1 spec: selector: matchLabels: run: flaskapp-1 replicas: 1 template: metadata: labels: run: flaskapp-1 spec: containers: - name: flaskapp-1 image: jcdemo/flaskapp ports: - containerPort: 5000 nodeSelector: name: xiao
部署 flaskapp-deployment.yaml,發現 pod 果然被排程到了 k8s-node01 這個 node,效果如下:
[root@k8s-master ~]# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES flaskapp-1-58b69c66f9-hv498 1/1 Running 0 7m30s 10.244.1.30 k8s-node01 <none> <none>
二、kiali 親和性排程
上面舉例 pod 使用 nodeSelector 選擇 node,這就是最簡單的 k8s 排程方式。
節點親和性排程策略示例:
apiVersion: v1 kind: Pod metadata: name: with-node-affinity spec: affinity: nodeAffinity: requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: kubernetes.io/e2e-az-name operator: In values: - e2e-az1 - e2e-az2 preferredDuringSchedulingIgnoredDuringExecution: - weight: 1 preference: matchExpressions: - key: another-node-label-key operator: In values: - another-node-label-value containers: - name: with-node-affinity image: k8s.gcr.io/pause:2.0
舉個例子
舉一個生活的例子,以前去醫院看病,病人(pod)不能挑醫生(node),排隊叫到誰就是誰,冷冰冰完全沒有親和性而言;如今可以網上掛號了,病人也可以挑選中意的醫生,這樣就有了親和性,說明社會進步了。
當然病人在挑選醫生的過程中也會有兩種情況:一種是硬性(required),比如非要某醫生,即使他忙,也願意一直等下去;還有一種是軟性(prefered),比如優先選擇某醫生,但是如果真不行,其他醫生也未嘗不可。
節點親和性排程(NodeAffinity)
下面的理論可以對照上面的例子。
節點親和性,也就是 NodeAffinity,用來控制 pod 部署或者不能部署在哪臺機器上。
節點親和性排程策略分為硬策略分為軟策略和硬策略兩種方式。硬策略是如果沒有滿足條件的節點,就會不斷重試直到條件滿足了為止;軟策略是如果沒有滿足條件的節點,pod 就會忽略這條規則,繼續完成排程過程。
節點親和性軟硬策略的語法分別介紹如下。
硬策略(關鍵字 require)
requiredDuringSchedulingIgnoredDuringExecution: pod 必須部署到滿足條件的節點上,如果節點不滿足條件,就不停重試。
軟策略(關鍵字 prefer)
preferredDuringSchedulingIgnoredDuringExecution: pod 優先部署到滿足條件的節點,如果節點不滿足條件,就忽略這些條件,排程到其他節點。
kiali 節點親和性排程
舉例1
apiVersion: apps/v1 kind: Deployment metadata: name: redis-cache spec: selector: matchLabels: app: store replicas: 3 template: metadata: labels: app: store spec: affinity: podAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - store topologyKey: "kubernetes.io/hostname" containers: - name: redis-server image: redis:3.2-alpine
建立了一個Deployment,副本數為3,指定了反親和規則如上所示,pod的label為app:store,那麼pod排程的時候將不會排程到node上已經運行了label為app:store的pod了,這樣就會使得Deployment的三副本分別部署在不同的host的node上.
舉例2
apiVersion: apps/v1 kind: Deployment metadata: name: redis-cache spec: selector: matchLabels: app: store replicas: 3 template: metadata: labels: app: store spec: affinity: podAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - web-store topologyKey: "kubernetes.io/hostname" podAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - store topologyKey: "kubernetes.io/hostname" containers: - name: web-app image: nginx:1.12-alpine
在一個例子中基礎之上,要求pod的親和性滿足requiredDuringSchedulingIgnoredDuringExecution中topologyKey=”kubernetes.io/hostname”,並且node上需要執行有app=store的label.
舉例3
apiVersion: apps/v1 kind: Deployment metadata: name: web-server spec: selector: matchLabels: app: web-server replicas: 3 template: metadata: labels: app: web-server spec: affinity: podAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - web-store topologyKey: "kubernetes.io/hostname" containers: - name: web-app image: hub.easystack.io/library/nginx:1.9.0
在一些應用中,pod副本之間需要共享cache,需要將pod執行在一個節點之上
本文參考連結:
https://blog.51cto.com/14268033/2487240
https://blog.csdn.net/jettery/article/details/79003562
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