7.k8s.调度器scheduler 亲和性、污点

#k8s. 调度器scheduler 亲和性、污点

默认调度过程：预选 Predicates (过滤节点) --> 优选 Priorities(优先级排序) --> 优先级最高节点

实际使用，根据需求控制Pod调度，需要用到如下:

指定节点、nodeAffinity(节点亲和性)、podAffinity(pod 亲和性)、 podAntiAffinity(pod 反亲和性)

#指定调度节点

# Pod.spec.nodeName 强制匹配，直接指定Node 节点，跳过 Scheduler 调度策略

#node-name-demo.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: demo-nodename
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: demo1
    spec:
      nodeName: node03  #指定Node节点
      containers:
      - name: demo1
        image: alivv/nginx:node
        ports:
        - containerPort: 80

#部署
kubectl apply -f node-name-demo.yaml
#查看pod全部在node03上 (node03节点不存在会一直处于pending)
kubectl get pod -o wide
#删除
kubectl delete -f node-name-demo.yaml

# Pod.spec.nodeSelector 强制约束，调度策略匹配 label，调度 Pod 到目标节点

#node-selector-demo.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: demo-node-selector
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: demo1
    spec:
      nodeSelector:
        test1: node  #匹配lable test1=node
      containers:
      - name: demo1
        image: alivv/nginx:node
        ports:
        - containerPort: 80

#部署
kubectl apply -f node-selector-demo.yaml

#查看pod处于pending
kubectl get pod -o wide
#给node02节点添加lable
kubectl label nodes node02 test1=node
kubectl get nodes --show-labels
#再次查看pod在node02节点
kubectl get pod -o wide

#删除
kubectl delete -f node-selector-demo.yaml
kubectl label nodes node02 test1-

亲和性调度

亲和性调度可以分成软策略和硬策略两种方式

• preferredDuringSchedulingIgnoredDuringExecution：软策略，没满足条件就忽略，Pod可以启动
• requiredDuringSchedulingIgnoredDuringExecution：硬策略，没满足条件就等待，Pod处于Pending

操作符

• In：label 的值在某个列表中
• NotIn：label 的值不在某个列表中
• Gt：label 的值大于某个值
• Lt：label 的值小于某个值
• Exists：某个 label 存在
• DoesNotExist：某个 label 不存在

#节点亲和性 pod.spec.nodeAffinity

#node-affinity-demo.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: node-affinity
  labels:
    app: affinity
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: affinity
    spec:
      containers:
      - name: nginx
        image: alivv/nginx:node
        ports:
        - containerPort: 80
          name: nginxweb
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:  #硬策略,不在node01节点
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/hostname
                operator: NotIn
                values:
                - node01
          preferredDuringSchedulingIgnoredDuringExecution:  #软策略,优先匹配test2=node
          - weight: 1
            preference:
              matchExpressions:
              - key: test2
                operator: In
                values:
                - node

#给node03节点添加lable
kubectl label nodes node03 test2=node
kubectl get nodes --show-labels

#部署
kubectl apply -f node-affinity-demo.yaml

#查看pod
kubectl get pod -o wide

#删除
kubectl delete -f node-affinity-demo.yaml
kubectl label nodes node03 test2-

#Pod亲和性pod.spec.affinity.podAffinity/podAntiAffinity

podAffinity Pod亲和性，解决 pod 部署在同一个拓扑域 、或同一个节点

podAntiAffinity Pod反亲和性，避开Pod部署在一起

#pod-affinity-demo.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: pod-affinity-demo
  labels:
    app: pod-affinity
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: pod-affinity
    spec:
      containers:
      - name: nginx
        image: alivv/nginx:node
        ports:
        - containerPort: 80
          name: nginxweb
      affinity:
        podAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:  #硬策略
          - labelSelector:  #匹配Pod有 app=demo1
              matchExpressions:
              - key: app
                operator: In
                values:
                - demo1
            topologyKey: kubernetes.io/hostname

#部署
kubectl apply -f pod-affinity-demo.yaml

#查看pod全部处于Pending 因为没标签app=demo1的Pod
kubectl get pod -o wide

#部署上面的node-name-demo.yaml
kubectl apply -f  node-name-demo.yaml
#再次查看pod全部在node03节点
kubectl get pod -o wide

#Pod反亲和性测试
#改podAffinity为podAntiAffinity
sed -i 's/podAffinity/podAntiAffinity/' pod-affinity-demo.yaml
kubectl apply -f pod-affinity-demo.yaml

#查看node03节点移除pod-affinity-demo
kubectl get pod -o wide

#删除
kubectl delete -f pod-affinity-demo.yaml
kubectl delete -f node-name-demo.yaml

# 污点taints与容忍tolerations

节点标记为 Taints ，除非 pod可以容忍污点节点，否则该 Taints 节点不会被调度pod

kubeadm安装k8s，默认master节点会添加NoSchedule 类型污点

污点设置 kubectl taint nodes node-name key=value:effect

key 和 value 为污点标签， value 可以为空，effect 描述污点的作用，effect 支持如下三个选项：

• NoSchedule 不会将 Pod 调度到有污点的 Node
• PreferNoSchedule 避免将 Pod 调度到有污点的 Node
• NoExecute 不会将 Pod 调度到有污点的 Node ，将已经存在的 Pod 驱逐出去

#给node03添加污点
kubectl taint nodes node03 test-taint=node:NoSchedule
#查看
kubectl describe node node03 |grep Taints

容忍 pod.spec.tolerations

#pod-tolerations-demo.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: pod-tolerations-demo
  labels:
    app: pod-tolerations
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: pod-tolerations
    spec:
      containers:
      - name: nginx
        image: alivv/nginx:node
        ports:
        - containerPort: 80
          name: http

#创建Pod
kubectl apply -f pod-tolerations-demo.yaml

#查看Pod，node03节点有污点将不会创建Pod
kubectl get pod -o wide

#文件pod-tolerations-demo.yaml追加容忍污点配置
echo '#容忍污点
      tolerations:
      - key: "test-taint"
        #value: "node"
        operator: "Exists"  #忽略value值
        effect: "NoSchedule"
'>>pod-tolerations-demo.yaml
cat pod-tolerations-demo.yaml

#更新
kubectl apply -f pod-tolerations-demo.yaml
#Pod扩容
kubectl scale deployment pod-tolerations-demo --replicas 5

#再次查看Pod，Node03有Pod
kubectl get pod -o wide

#删除Pod
kubectl delete -f pod-tolerations-demo.yaml
#删除污点
kubectl taint nodes node03 test-taint-

#不指定 key 值时，容忍所有的污点 key

tolerations:
- operator: "Exist

#不指定 effect 值时，表示容忍所有的污点作用

tolerations:
- key: "key"
  operator: "Exist"

#避免资源浪费，设置master运行Pod，可以如下配置：

kubectl taint nodes --all  node-role.kubernetes.io/master- #先删除默认污点
kubectl taint nodes Node-Name node-role.kubernetes.io/master=:PreferNoSchedule

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Blog地址 https://www.cnblogs.com/elvi/p/11755828.html

本文git地址 https://gitee.com/almi/k8s/tree/master/notes