k8s-Pod调度策略

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

4. 资源影响调度

 

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

  

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

  

4. 资源影响调度

在创建pod 的时候会配置resource 来设定容器需要的CPU 和memory,,主要是包括 requsts 和 limits,, 当然schedule 在调度的时候也会根据node 上剩余资源的情况,来调度pod 在哪个节点上。这里就不做具体演示了。

 

原文:https://blog.csdn.net/ht9999i/article/details/108037568

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