k8s-Pod调度策略（入门攻略）

标签：node myapp master 攻略 Pod k8s root pod

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

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

标签：node,myapp,master,攻略,Pod,k8s,root,pod
From： https://blog.51cto.com/u_15376515/6364894