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，
node节点调度器
亲和性调度
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
