istio kiali 亲和性调度

一、节点调度

在开始 kiali 亲和性调度之前,先演示一个简单的例子介绍 pod 选择调度到指定 node:

 

节点打标

使用命令查看当前所有 k8s 节点:

[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

 

现在给 k8s-w-206 这个节点打上一个标签,标签内容为 name: xiao,命令如下:

kubectl label node k8s-node01 name=xiao

 

编写 pod

编写 pod 资源文件flaskapp-deployment.yaml,文件中使用 nodeSelector 指定该 pod 要调度到 k8s-node01节点之上

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,发现 pod 果然被调度到了 k8s-node01 这个 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 亲和性调度

上面举例 pod 使用 nodeSelector 选择 node,这就是最简单的 k8s 调度方式。

节点亲和性调度策略示例:

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

 

举个例子

举一个生活的例子,以前去医院看病,病人(pod)不能挑医生(node),排队叫到谁就是谁,冷冰冰完全没有亲和性而言;如今可以网上挂号了,病人也可以挑选中意的医生,这样就有了亲和性,说明社会进步了。

 

当然病人在挑选医生的过程中也会有两种情况:一种是硬性(required),比如非要某医生,即使他忙,也愿意一直等下去;还有一种是软性(prefered),比如优先选择某医生,但是如果真不行,其他医生也未尝不可。

 

节点亲和性调度(NodeAffinity)

下面的理论可以对照上面的例子。

节点亲和性,也就是 NodeAffinity,用来控制 pod 部署或者不能部署在哪台机器上。

节点亲和性调度策略分为硬策略分为软策略和硬策略两种方式。硬策略是如果没有满足条件的节点,就会不断重试直到条件满足了为止;软策略是如果没有满足条件的节点,pod 就会忽略这条规则,继续完成调度过程。

 

节点亲和性软硬策略的语法分别介绍如下。

硬策略(关键字 require)

requiredDuringSchedulingIgnoredDuringExecution:

pod 必须部署到满足条件的节点上,如果节点不满足条件,就不停重试。

 

软策略(关键字 prefer)

preferredDuringSchedulingIgnoredDuringExecution:

pod 优先部署到满足条件的节点,如果节点不满足条件,就忽略这些条件,调度到其他节点。

 

kiali 节点亲和性调度

举例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

创建了一个Deployment,副本数为3,指定了反亲和规则如上所示,pod的label为app:store,那么pod调度的时候将不会调度到node上已经运行了label为app:store的pod了,这样就会使得Deployment的三副本分别部署在不同的host的node上.

 

举例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

在一个例子中基础之上,要求pod的亲和性满足requiredDuringSchedulingIgnoredDuringExecution中topologyKey=”kubernetes.io/hostname”,并且node上需要运行有app=store的label.

 

举例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

在一些应用中,pod副本之间需要共享cache,需要将pod运行在一个节点之上

 

 

本文参考链接:

//blog.51cto.com/14268033/2487240

//blog.csdn.net/jettery/article/details/79003562