k8s-Pod调度策略（入门攻略）

喜欢ヅ旅行 2022-11-28 00:43 177阅读 0赞

首先在k8s中，k8s会根据每个work节点的配置，负载差异，自动生成优选函数，根据优选函数，当master节点分配下来任务时，将pod分配带最适合运行的node节点上。

之外我们技术人员还有以下三种方式去影响我们的pod调度，

1.  node节点调度器
2.  亲和性调度
3.  污点容忍度

区别和实例操作

## 一 .node节点调度 ##

是最直接的调度方式，简单粗暴，所以常用在简单的集群架构中，负载的资源分类和编制不适合这种方式，  
**解释**：大概意思就是给我们的work节点绑定唯一便签，然后在pod的yml文件中去设置node便签匹配器绑定节点，这样就能实现影响k8s优选参数的选择，让当前的pod启动在设置的node节点上。

##### 1、首先通过 kubectl 给 node 打上标签 #####

格式：
    kubectl label nodes <node-name> <label-key>=<label-value>
    [root@k8s-master ~]# kubectl label nodes k8s-node01 zone=sh
    [root@k8s-master ~]# kubectl get nodes --show-labels

##### 2、通过 nodeSelector 调度 pod 到 node #####

*  Pod的定义中通过nodeSelector指定label标签，pod将会只调度到具有该标签的node之上

[root@k8s-master ~]# vim pod-demo.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      name: nginx
      labels:
        env: test
    spec:
      containers:
      - name: nginx
        image: nginx
        imagePullPolicy: IfNotPresent
      nodeSelector:
        disktype: ssd

*  这个例子中pod只会调度到具有 disktype=ssd 的 node 上面．
 *  验证 节点调度

[root@k8s-master ~]# kubectl apply -f pod-demo.yaml 
    [root@k8s-master ~]# kubectl get pods -o wide
    [root@k8s-master ~]# kubectl describe pod pod-demo ##查看事件

## 二 .亲和性调度 ##

较复杂，应用在复杂的多节点归类，资源分类管理的中大型集群中，有硬亲和，软亲和，亲和性和反亲和，两两为一组，反义词

--------------------

硬亲和：匹配节点上的其中一个或多个标签（必须存在一个）  
软亲和：匹配节点上的其中一个或多个标签（有则选择这个node，没有就参考优选函数）

#### 1.硬亲和 ####

[root@k8s-master ~]# vim pod-nodeaffinity-demo.yaml 
    apiVersion: v1
    kind: Pod
    metadata:
      name: pod-node-affinity-demo
      labels:
        app: myapp
        tier: frontend
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: zone
                operator: In
                values:
                - foo
                - bar
    
    [root@k8s-master ~]# kubectl apply -f pod-nodeaffinity-demo.yaml
    
    [root@k8s-master ~]# kubectl describe pod pod-node-affinity-demo
    # 运行结果:
    Warning  FailedScheduling  2s (x8 over 20s)  default-scheduler  0/3 nodes are available: 3 node(s) didn't match node selector.
    
    # 给其中一个node打上foo的标签
    [root@k8s-master ~]# kubectl label node k8s-node01 zone=foo
    
    # 正常启动
    [root@k8s-master ~]# kubectl get pods

#### 2.软亲和 ####

[root@k8s-master ~]# vim pod-nodeaffinity-demo-2.yaml 
    apiVersion: v1
    kind: Pod
    metadata:
      name: pod-node-affinity-demo-2
      labels:
        app: myapp
        tier: frontend
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
      affinity:
        nodeAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - preference:
              matchExpressions:
              - key: zone
                operator: In
                values:
                - foo
                - bar
            weight: 60
          - preference:
              matchExpressions:
              - key: zone1
                operator: In
                values:
                - foo1
                - bar1
            weight: 10 
    
    [root@k8s-master ~]# kubectl apply -f pod-nodeaffinity-demo-2.yaml

#### 3.同时存在时（硬，软亲和） ####

apiVersion: v1
    kind: Pod
    metadata:
      name: with-node-affinity
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: zone
                operator: In
                values:
                - dev
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 1
            preference:
              matchExpressions:
              - key: disktype
                operator: In
                values:
                - ssd
      containers:
      - name: with-node-affinity
        image: nginx

结果：同时存在的话先判断上下顺序，从上到下选择范围，列如硬亲和在上，软亲和在下，就会先选必须匹配到一个标签的多个node上，然后软亲和继续从这些节点去选择，反之亦然。

--------------------

亲和性：首先是先有一个pod，然后根据上一个pod（辨识标签）在哪里节点启动，就会跟随到这个节点上去启动。  
反亲和：查看前面的那个pod的启动节点，必须和它启动到不是一个节点上

#### 1.亲和性 ####

[root@k8s-master ~]# vim pod-required-affinity-demo.yaml 
    apiVersion: v1
    kind: Pod
    metadata:
      name: pod-first
      labels:
        app: myapp
        tier: frontend
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
    ---
    apiVersion: v1
    kind: Pod
    metadata:
      name: pod-second
      labels:
        app: db
        tier: db
    spec:
      containers:
      - name: busybox
        image: busybox
        imagePullPolicy: IfNotPresent
        command: ["sh","-c","sleep 3600"]
      affinity:
        podAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - { key: app, operator: In, values: ["myapp"]}
            topologyKey: kubernetes.io/hostname
    
    
    [root@k8s-master ~]# kubectl apply -f pod-required-affinity-demo.yaml 
    
    [root@k8s-master ~]# kubectl get pods -o wide
    # 运行结果，两个 pod 在同一 node 节点上
    NAME         READY   STATUS    RESTARTS   AGE   IP           NODE
    pod-first    1/1     Running   0          11s   10.244.1.6   k8s-node01
    pod-second   1/1     Running   0          11s   10.244.1.5   k8s-node01
    
    [root@k8s-master ~]# kubectl delete -f pod-required-affinity-demo.yaml

#### 2.反亲和性 ####

[root@k8s-master ~]# vim pod-required-anti-affinity-demo.yaml 
    # 内容为
    apiVersion: v1
    kind: Pod
    metadata:
      name: pod-first
      labels:
        app: myapp
        tier: frontend
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
    ---
    apiVersion: v1
    kind: Pod
    metadata:
      name: pod-second
      labels:
        app: backend
        tier: db
    spec:
      containers:
      - name: busybox
        image: busybox:latest
        imagePullPolicy: IfNotPresent
        command: ["sh","-c","sleep 3600"]
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - { key: app, operator: In, values: ["myapp"]}
            topologyKey: kubernetes.io/hostname
    
    [root@k8s-master ~]# kubectl apply -f pod-required-anti-affinity-demo.yaml 
    
    [root@k8s-master ~]# kubectl get pods -o wide
    # 运行结果，两个 pod 不在同一个 node
    NAME         READY   STATUS    RESTARTS   AGE   IP           NODE
    pod-first    1/1     Running   0          5s    10.244.2.4   k8s-node02
    pod-second   1/1     Running   0          5s    10.244.1.7   k8s-node01
    
    [root@k8s-master ~]# kubectl delete -f pod-required-anti-affinity-demo.yaml

#### 3.同时存在时（亲和性，反亲和性） ####

这里就不举例的，直接说一下结果  
首先肯定是两个条件的匹配条件不能一样  
这时候就会满足两个条件去选择条件，比如，当亲和性在上，反亲和在下，pod会先选择匹配到条件的一些节点上去选择，然后在从中匹配到反亲和的条件，如果有那就必须踢出它，选择其他符合条件的节点。

## 三.污点和容忍度 ##

与之前两个调度方式不同，污点是首先给节点绑定污点，作用是保护节点，不再让这个节点会scheduler（资源调度）选为pod启动环境。  
我们集群中master就是设置污点，所以你启动任何pod都不会在master上工作，保证master的工作效率。

#### 相关参数 ####

介绍几个用到的参数

*  operator 可以定义为
    
     *  Equal：表示key是否等于value，默认
     *  Exists：表示key是否存在，此时无需定义value
 *  tain 的 effect 定义对 Pod 排斥效果
    
     *  NoSchedule：仅影响调度过程，对现存的Pod对象不产生影响；
     *  NoExecute：既影响调度过程，也影响现有的Pod对象；不容忍的Pod对象将被驱逐
     *  PreferNoSchedule: 表示尽量不调度

##### 查看节点的污点 #####

kubectl describe node k8s-node01 | grep Taints

##### 设置污点 #####

kubectl taint node k8s-node01 node-type=production:NoSchedule

##### 创建容器测试 #####

[root@k8s-master ~]# vim deploy-demo.yaml 
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: myapp-deploy
      namespace: default
    spec:
      replicas: 2
      selector:
        matchLabels:
          app: myapp
          release: canary
      template:
        metadata:
          labels:
            app: myapp
            release: canary
        spec:
          containers:
          - name: myapp
            image: ikubernetes/myapp:v1
            ports:
            - name: http
              containerPort: 80
    
    [root@k8s-master ~]# kubectl apply -f deploy-demo.yaml 
    
    [root@k8s-master ~]# kubectl get pods -o wide
    # 运行结果：
    NAME                            READY   STATUS    RESTARTS   AGE   IP           NODE
    myapp-deploy-69b47bc96d-cwt79   1/1     Running   0          5s    10.244.2.6   k8s-node02
    myapp-deploy-69b47bc96d-qqrwq   1/1     Running   0          5s    10.244.2.5   k8s-node02

所以只能启动到没有污点的node2节点上

##### 设置一个能容忍node1污点的pod测试 #####

[root@k8s-master ~]# vim deploy-demo.yaml 
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: myapp-deploy
      namespace: defaultm
    spec:
      replicas: 2
      selector:
        matchLabels:
          app: myapp
          release: canary
      template:
        metadata:
          labels:
            app: myapp
            release: canary
        spec:
          containers:
          - name: myapp
            image: ikubernetes/myapp:v2
            ports:
            - name: http
              containerPort: 80
          tolerations:
          - key: "node-type"
            operator: "Equal"
            value: "production"
            effect: "NoSchedule"
    
    
    [root@k8s-master ~]# kubectl apply -f deploy-demo.yaml

测试

[root@k8s-master ~]# kubectl get pods -o wide
    NAME                            READY   STATUS    RESTARTS   AGE   IP            NODE
    myapp-deploy-65cc47f858-tmpnz   1/1     Running   0          10s   10.244.1.10   k8s-node01
    myapp-deploy-65cc47f858-xnklh   1/1     Running   0          13s   10.244.1.9    k8s-node01

##### 其他参数的作用 #####

*  定义Toleration，是否存在 node-type 这个key 且 effect 值为 NoSchedule

[root@k8s-master ~]# vim deploy-demo.yaml 
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: myapp-deploy
      namespace: default
    spec:
      replicas: 2
      selector:
        matchLabels:
          app: myapp
          release: canary
      template:
        metadata:
          labels:
            app: myapp
            release: canary
        spec:
          containers:
          - name: myapp
            image: ikubernetes/myapp:v2
            ports:
            - name: http
              containerPort: 80
          tolerations:
          - key: "node-type"
            operator: "Exists"
            value: ""
            effect: "NoSchedule"
    
    [root@k8s-master ~]# kubectl apply -f deploy-demo.yaml
    
    [root@k8s-master ~]# kubectl get pods -o wide
    NAME                            READY   STATUS    RESTARTS   AGE   IP            NODE
    myapp-deploy-559f559bcc-6jfqq   1/1     Running   0          10s   10.244.1.11   k8s-node01
    myapp-deploy-559f559bcc-rlwp2   1/1     Running   0          9s    10.244.1.12   k8s-node01

*  定义Toleration，是否存在 node-type 这个key 且 effect 值为空，则包含所有的值

[root@k8s-master ~]# vim deploy-demo.yaml 
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: myapp-deploy
      namespace: default
    spec:
      replicas: 2
      selector:
        matchLabels:
          app: myapp
          release: canary
      template:
        metadata:
          labels:
            app: myapp
            release: canary
        spec:
          containers:
          - name: myapp
            image: ikubernetes/myapp:v2
            ports:
            - name: http
              containerPort: 80
          tolerations:
          - key: "node-type"
            operator: "Exists"
            value: ""
            effect: ""
    
    [root@k8s-master ~]# kubectl apply -f deploy-demo.yaml
    
    # 两个 pod 均衡调度到两个节点
    kubectl get pods -o wide
    NAME                            READY   STATUS    RESTARTS   AGE   IP            NODE
    myapp-deploy-5d9c6985f5-hn4k2   1/1     Running   0          2m    10.244.1.13   k8s-node01
    myapp-deploy-5d9c6985f5-lkf9q   1/1     Running   0          2m    10.244.2.7    k8s-node02

--------------------

**------没有足够的努力，就不要去谈未来和远方，因为谁不会吹呢------**