关于K8s中Pod调度[选择器,指定节点,主机亲和性]方式和节点[coedon,drain,taint]标记的Demo

Posted 2022-05-30 山河已无恙

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了关于K8s中Pod调度[选择器,指定节点,主机亲和性]方式和节点[coedon,drain,taint]标记的Demo相关的知识，希望对你有一定的参考价值。

写在前面

嗯，整理K8s中pod调度相关笔记，这里分享给小伙伴
博文内容涉及：
- kube-scheduler组件的简述
- Pod的调度(选择器、指定节点、主机亲和性)方式
- 节点的coedon与drain标记
- 节点的taint(污点)标记及pod的容忍污点(tolerations)定义
食用方式：
- 需要了解K8s基础知识
- 熟悉资源对象pod，deploy的创建，了解资源对象定义yaml文件
- 了解kubectl常用命令
理解不足小伙伴帮忙指正

所谓成功就是用自己的方式度过人生。--------《明朝那些事》

Scheduler 调度组件简述

Kubernetes Scheduler是什么

众多周知，Kubernetes Scheduler 是 Kubernetes中负责Pod调度的重要功能模块，运行在k8s 集群中的master节点。

作用 : Kubernetes Scheduler的作用是将待调度的Pod (API新创建的Pod, Controller Manager为补足副本而创建的Pod等)按照特定的调度算法和调度策略绑定(Binding)到集群中某个合适的Node上,并将绑定信息写入etcd中。

在整个调度过程中涉及三个对象,分别是

待调度Pod列表
可用Node列表
以及调度算法和策略

整体流程 :通过调度算法调度,为待调度Pod列表中的每个Pod从Node列表中选择一个最适合的Node随后, 目标node节点上的kubelet通过APIServer监听到Kubernetes Scheduler产生的Pod绑定事件,然后获取对应的Pod清单,下载Image镜像并启动容器。

kubelet进程通过与API Server的交互，每隔一个时间周期,就会调用一次API Server的REST接口报告自身状态, API Server接收到这些信息后,将节点状态信息更新到etcd中。同时kubelet也通过API Server的Watch接口监听Pod信息,

如果监听到新的Pod副本被调度绑定到本节点,则执行Pod对应的容器的创建和启动逻辑;
如果监听到Pod对象被删除,则删除本节点上的相应的Pod容器;
如果监听到修改Pod信息,则kubelet监听到变化后,会相应地修改本节点的Pod容器。

所以说，kubernetes Schedule 在整个系统中承担了承上启下的重要功能，对上负责接收声明式API或者控制器创建新pod的消息，并且为其安排一个合适的Node，对下，选择好node之后，把工作交接给node上的kubelet，由kubectl负责pod的剩余生命周期。

Kubernetes Scheduler调度流程

Kubernetes Scheduler当前提供的默认调度流程分为以下两步。这部分随版本一直变化，小伙伴以官网为主

流程	描述
预选调度过程	即遍历所有目标Node,筛选出符合要求的候选节点。为此, Kubernetes内置了多种预选策略(xxx Predicates)供用户选择
确定最优节点	在第1步的基础上,采用优选策略(xxxPriority)计算出每个候选节点的积分,积分最高者胜出

Kubernetes Scheduler的调度流程是通过插件方式加载的"调度算法提供者” (AlgorithmProvider)具体实现的。一个AlgorithmProvider其实就是包括了一组预选策略与一组优先选择策略的结构体.

Scheduler中可用的预选策略包含：NoDiskConflict、PodFitsResources、PodSelectorMatches、PodFitsHost、CheckNodeLabelPresence、CheckServiceAffinity 和PodFitsPorts策略等。

其默认的AlgorithmProvider加载的预选策略返回布尔值包括：

PodFitsPorts（PodFitsPorts）：判断端口是否冲突
PodFitsResources（PodFitsResources）：判断备选节点的资源是否满足备选Pod的需求
NoDiskConflict（NoDiskConflict）：判断备选节点和已有节点是否磁盘冲突
MatchNodeSelector（PodSelectorMatches）：判断备选节点是否包含备选Pod的标签选择器指定的标签。
HostName（PodFitsHost）:判断备选Pod的spec.nodeName域所指定的节点名称和备选节点的名称是否一致

即每个节点只有通过前面提及的5个默认预选策略后，才能初步被选中，进入到确认最优节点(优选策略)流程。

Scheduler中的优选策略包含(不限于下面3个)：

LeastRequestedPriority:从备选节点列表中选出资源消耗最小的节点,对各个节点公式打分
CalculateNodeLabelPriority：判断策略列出的标签在备选节点中存在时，是否选择该备选节,这不太懂，打分
BalancedResourceAllocation：从备选节点列表中选出各项资源使用率最均衡的节点。对各个节点公式打分

每个节点通过优先选择策略时都会算出一个得分，计算各项得分，最终选出得分值最大的节点作为优选的结果（也是调度算法的结果）。

Pod的调度

手动指定pod的运行位置:

通过给node节点设置指定的标签，然后我们可以在创建pod里指定通过选择器选择node标签，类似前端里面DOM操作元素定位，或者直接指定节点名

节点标签常用命令

标签设置	–
查看	kubectl get nodes --show-labels
设置	kubectl label node node2 disktype=ssd
取消	kubectl label node node2 disktype
所有节点设置	kubectl label node all key=vale

给节点设置标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl label node vms82.liruilongs.github.io disktype=node1
node/vms82.liruilongs.github.io labeled
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl label node vms83.liruilongs.github.io disktype=node2
node/vms83.liruilongs.github.io labeled

查看节点标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl get node --show-labels
NAME                         STATUS   ROLES                  AGE   VERSION   LABELS
vms81.liruilongs.github.io   Ready    control-plane,master   45d   v1.22.2   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=vms81.liruilongs.github.io,kubernetes.io/os=linux,node-role.kubernetes.io/control-plane=,node-role.kubernetes.io/master=,node.kubernetes.io/exclude-from-external-load-balancers=
vms82.liruilongs.github.io   Ready    <none>                 45d   v1.22.2   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disktype=node1,kubernetes.io/arch=amd64,kubernetes.io/hostname=vms82.liruilongs.github.io,kubernetes.io/os=linux
vms83.liruilongs.github.io   Ready    <none>                 45d   v1.22.2   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,disktype=node2,kubernetes.io/arch=amd64,kubernetes.io/hostname=vms83.liruilongs.github.io,kubernetes.io/os=linux
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$

特殊的内置标签node-role.kubernetes.io/control-plane=,node-role.kubernetes.io/master=,用于设置角色列roles

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl get node
NAME                         STATUS   ROLES                  AGE   VERSION
vms81.liruilongs.github.io   Ready    control-plane,master   45d   v1.22.2
vms82.liruilongs.github.io   Ready    <none>                 45d   v1.22.2
vms83.liruilongs.github.io   Ready    <none>                 45d   v1.22.2

我们也可以做worker节点上设置标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl label nodes vms82.liruilongs.github.io node-role.kubernetes.io/worker1=
node/vms82.liruilongs.github.io labeled
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl label nodes vms83.liruilongs.github.io node-role.kubernetes.io/worker2=
node/vms83.liruilongs.github.io labeled

查看标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl get node
NAME                         STATUS   ROLES                  AGE   VERSION
vms81.liruilongs.github.io   Ready    control-plane,master   45d   v1.22.2
vms82.liruilongs.github.io   Ready    worker1                45d   v1.22.2
vms83.liruilongs.github.io   Ready    worker2                45d   v1.22.2
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$

选择器(`nodeSelector`)方式

在特定节点上运行pod,给vms83.liruilongs.github.io节点打disktype=node2的标签，yaml文件选择器指定对应的标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get nodes -l disktype=node2
NAME                         STATUS   ROLES     AGE   VERSION
vms83.liruilongs.github.io   Ready    worker2   45d   v1.22.2
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$vim pod-node2.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply  -f pod-node2.yaml
pod/podnode2 created

pod-node2.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podnode2
  name: podnode2
spec:
  nodeSelector:
    disktype: node2
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: podnode2
    resources: 
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status:

pod被调度到了vms83.liruilongs.github.io

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -owide
NAME       READY   STATUS    RESTARTS   AGE   IP               NODE                         NOMINATED NODE   READINESS GATES
podnode2   1/1     Running   0          13m   10.244.70.60     vms83.liruilongs.github.io   <none>           <none>

指定节点名称(`nodeName`)的方式

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$vim pod-node1.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply -f pod-node1.yaml
pod/podnode1 created

pod-node1.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podnode1
  name: podnode1
spec:
  nodeName: vms82.liruilongs.github.io
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: podnode1
    resources: 
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status:

需要注意 当pod资源文件指定的节点标签,或者节点名不存在时，这个pod资源是无法创建成功的

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -owide
NAME       READY   STATUS    RESTARTS   AGE   IP               NODE                         NOMINATED NODE   READINESS GATES
podnode1   1/1     Running   0          36s   10.244.171.165   vms82.liruilongs.github.io   <none>           <none>
podnode2   1/1     Running   0          13m   10.244.70.60     vms83.liruilongs.github.io   <none>           <none>

主机亲和性

所谓主机亲和性，即在满足指定条件的节点上运行。分为硬策略(必须满足)，软策略(最好满足)

硬策略(`requiredDuringSchedulingIgnoredDuringExecution`)

所调度节点的标签必须为其中的一个，这个标签是一个默认标签，会自动添加

  affinity:
    nodeAffinity: #主机亲和性
      requiredDuringSchedulingIgnoredDuringExecution: #硬策略
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - vms85.liruilongs.github.io
            - vms84.liruilongs.github.io

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply -f pod-node-a.yaml
pod/podnodea created

pod-node-a.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podnodea
  name: podnodea
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: podnodea
    resources: 
  affinity:
    nodeAffinity: #主机亲和性
      requiredDuringSchedulingIgnoredDuringExecution: #硬策略
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - vms85.liruilongs.github.io
            - vms84.liruilongs.github.io
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status:

条件不满足，所以 Pending

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods
NAME       READY   STATUS    RESTARTS   AGE
podnodea   0/1     Pending   0          8s

我修改一下，修改为存在的标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$sed -i  's/vms84.liruilongs.github.io/vms83.liruilongs.github.io/' pod-node-a.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply -f pod-node-a.yaml
pod/podnodea created

可以发现pod调度成功

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -owide
NAME       READY   STATUS    RESTARTS   AGE   IP             NODE                         NOMINATED NODE   READINESS GATES
podnodea   1/1     Running   0          13s   10.244.70.61   vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

软策略(`preferredDuringSchedulingIgnoredDuringExecution`)

所调度节点尽量为其中一个

  affinity:
    nodeAffinity: #主机亲和性
      preferredDuringSchedulingIgnoredDuringExecution: # 软策略
      - weight: 2
        preference:
          matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - vms85.liruilongs.github.io
            - vms84.liruilongs.github.io

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$vim pod-node-a-r.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply -f  pod-node-a-r.yaml
pod/podnodea created

pod-node-a-r.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podnodea
  name: podnodea
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: podnodea
    resources: 
  affinity:
    nodeAffinity: #主机亲和性
      preferredDuringSchedulingIgnoredDuringExecution: # 软策略
      - weight: 2
        preference:
          matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - vms85.liruilongs.github.io
            - vms84.liruilongs.github.io
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status:

检查一下,调度OK

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -owide
NAME       READY   STATUS    RESTARTS   AGE   IP             NODE                         NOMINATED NODE   READINESS GATES
podnodea   1/1     Running   0          28s   10.244.70.62   vms83.liruilongs.github.io   <none>           <none>

常见的标签运算符

运算符	描述
In	包含自, 比如上面的硬亲和就包含env_role=dev、env_role=test两种标签
NotIn	和上面相反，凡是包含该标签的节点都不会匹配到
Exists	存在里面和In比较类似，凡是有某个标签的机器都会被选择出来。使用Exists的operator的话，values里面就不能写东西了。
Gt	greater than的意思，表示凡是某个value大于设定的值的机器则会被选择出来。
Lt	less than的意思，表示凡是某个value小于设定的值的机器则会被选择出来。
DoesNotExists	不存在该标签的节点

节点的coedon与drain

如果想把某个节点设置为不可用的话，可以对节点实施cordon或者drain

如果一个node被标记为cordon，新创建的pod不会被调度到此node上，已经调度上去的不会被移走，coedon用于节点的维护，当不希望再节点分配pod，那么可以使用coedon把节点标记为不可调度。

这里我们为了方便，创建一个Deployment控制器用去用于演示，deploy拥有3个pod副本

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl create deployment nginx  --image=nginx  --dry-run=client -o yaml >nginx-dep.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$vim nginx-dep.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply  -f nginx-dep.yaml
deployment.apps/nginx created

nginx-dep.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: nginx
  name: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  strategy: 
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx
        name: nginx
        imagePullPolicy: IfNotPresent
        resources: 
status:

可以看到pod调度到了两个工作节点

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -owide
NAME                     READY   STATUS    RESTARTS   AGE     IP               NODE
      NOMINATED NODE   READINESS GATES
nginx-7cf7d6dbc8-hx96s   1/1     Running   0          2m16s   10.244.171.167   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-wshxp   1/1     Running   0          2m16s   10.244.70.1      vms83.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-x78x4   1/1     Running   0          2m16s   10.244.70.63     vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

节点的`coedon`

基本命令

kubectl cordon vms83.liruilongs.github.io  #标记不可用
kubectl uncordon vms83.liruilongs.github.io #取消标记

通过cordon把vms83.liruilongs.github.io标记为不可调度

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl cordon vms83.liruilongs.github.io  #通过cordon把83标记为不可调度
node/vms83.liruilongs.github.io cordoned

查看节点状态，vms83.liruilongs.github.io变成SchedulingDisabled

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get nodes
NAME                         STATUS                     ROLES                  AGE   VERSION
vms81.liruilongs.github.io   Ready                      control-plane,master   48d   v1.22.2
vms82.liruilongs.github.io   Ready                      worker1                48d   v1.22.2
vms83.liruilongs.github.io   Ready,SchedulingDisabled   worker2                48d   v1.22.2

修改deployment副本数量 --replicas=6

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl scale deployment nginx  --replicas=6
deployment.apps/nginx scaled

新增的pod都调度到了vms82.liruilongs.github.io 节点

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide
NAME                     READY   STATUS    RESTARTS   AGE     IP               NODE                         NOMINATED NODE   READINESS GATES
nginx-7cf7d6dbc8-2nmsj   1/1     Running   0          64s     10.244.171.170   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-chsrn   1/1     Running   0          63s     10.244.171.168   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-hx96s   1/1     Running   0          7m30s   10.244.171.167   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-lppbp   1/1     Running   0          63s     10.244.171.169   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-wshxp   1/1     Running   0          7m30s   10.244.70.1      vms83.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-x78x4   1/1     Running   0          7m30s   10.244.70.63     vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

把vms83.liruilongs.github.io节点上的pod都干掉，会发现新增pod都调度到了vms82.liruilongs.github.io

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl delete pod nginx-7cf7d6dbc8-wshxp
pod "nginx-7cf7d6dbc8-wshxp" deleted
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide
NAME                     READY   STATUS    RESTARTS   AGE     IP               NODE                         NOMINATED NODE   READINESS GATES
nginx-7cf7d6dbc8-2nmsj   1/1     Running   0          2m42s   10.244.171.170   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-5hnc7   1/1     Running   0          10s     10.244.171.171   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-chsrn   1/1     Running   0          2m41s   10.244.171.168   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-hx96s   1/1     Running   0          9m8s    10.244.171.167   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-lppbp   1/1     Running   0          2m41s   10.244.171.169   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-x78x4   1/1     Running   0          9m8s    10.244.70.63     vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl delete pod nginx-7cf7d6dbc8-x78x4
pod "nginx-7cf7d6dbc8-x78x4" deleted

pod都位于正常的节点

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide
NAME                     READY   STATUS    RESTARTS   AGE     IP               NODE                         NOMINATED NODE   READINESS GATES
nginx-7cf7d6dbc8-2nmsj   1/1     Running   0          3m31s   10.244.171.170   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-5hnc7   1/1     Running   0          59s     10.244.171.171   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-chsrn   1/1     Running   0          3m30s   10.244.171.168   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-hx96s   1/1     Running   0          9m57s   10.244.171.167   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-lppbp   1/1     Running   0          3m30s   10.244.171.169   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-m8ltr   1/1     Running   0          30s     10.244.171.172   vms82.liruilongs.github.io   <none>           <none>

通过 uncordon恢复节点vms83.liruilongs.github.io状态

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl uncordon vms83.liruilongs.github.io #恢复节点状态
node/vms83.liruilongs.github.io uncordoned
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get nodes
NAME                         STATUS   ROLES                  AGE   VERSION
vms81.liruilongs.github.io   Ready    control-plane,master   48d   v1.22.2
vms82.liruilongs.github.io   Ready    worker1                48d   v1.22.2
vms83.liruilongs.github.io   Ready    worker2                48d   v1.22.2

删除所有的pod

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl scale deployment nginx --replicas=0
deployment.apps/nginx scaled
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide
No resources found in liruilong-pod-create namespace.

节点的`drain`

如果一个节点被设置为drain，则此节点不再被调度pod，且此节点上已经运行的pod会被驱逐(evicted)到其他节点

drain包含两种状态：cordon不可被调度，evicted驱逐当前节点所以pod

kubectl drain vms83.liruilongs.github.io   --ignore-daemonsets
kubectl uncordon vms83.liruilongs.github.io

通过deployment添加4个nginx副本--replicas=4

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl scale deployment nginx --replicas=4
deployment.apps/nginx scaled
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide --one-output
NAME                     READY   STATUS    RESTARTS   AGE   IP               NODE                         NOMINATED NODE   READINESS GATES
nginx-7cf7d6dbc8-2clnb   1/1     Running   0          22s   10.244.171.174   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-9p6g2   1/1     Running   0          22s   10.244.70.2      vms83.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-ptqxm   1/1     Running   0          22s   10.244.171.173   vms82.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-zmdqm   1/1     Running   0          22s   10.244.70.4      vms83.liruilongs.github.io   <none>           <none>

添加一下drain 将节点vms82.liruilongs.github.io设置为drain

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl drain vms82.liruilongs.github.io --ignore-daemonsets --delete-emptydir-data
node/vms82.liruilongs.github.io cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/calico-node-ntm7v, kube-system/kube-proxy-nzm24
evicting pod liruilong-pod-create/nginx-7cf7d6dbc8-ptqxm
evicting pod kube-system/metrics-server-bcfb98c76-wxv5l
evicting pod liruilong-pod-create/nginx-7cf7d6dbc8-2clnb
pod/nginx-7cf7d6dbc8-2clnb evicted
pod/nginx-7cf7d6dbc8-ptqxm evicted
pod/metrics-server-bcfb98c76-wxv5l evicted
node/vms82.liruilongs.github.io evicted

查看节点，状态为不可被调度

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get nodes
NAME                         STATUS                     ROLES                  AGE   VERSION
vms81.liruilongs.github.io   Ready                      control-plane,master   48d   v1.22.2
vms82.liruilongs.github.io   Ready,SchedulingDisabled   worker1                48d   v1.22.2
vms83.liruilongs.github.io   Ready                      worker2                48d   v1.22.2

等一会，查看节点调度，所有pod调度到了vms83.liruilongs.github.io这台机器

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide --one-output
NAME                     READY   STATUS    RESTARTS   AGE     IP            NODE                         NOMINATED NODE   READINESS GATES
nginx-7cf7d6dbc8-9p6g2   1/1     Running   0          4m20s   10.244.70.2   vms83.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-hkflr   1/1     Running   0          25s     10.244.70.5   vms83.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-qt48k   1/1     Running   0          26s     10.244.70.7   vms83.liruilongs.github.io   <none>           <none>
nginx-7cf7d6dbc8-zmdqm   1/1     Running   0          4m20s   10.244.70.4   vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

取消drain：kubectl uncordon vms82.liruilongs.github.io

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl uncordon vms82.liruilongs.github.io
node/vms82.liruilongs.github.io uncordoned
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

有时候会报错

将节点vms82.liruilongs.github.io设置为drain

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl drain vms82.liruilongs.github.io
node/vms82.liruilongs.github.io cordoned
DEPRECATED WARNING: Aborting the drain command in a list of nodes will be deprecated in v1.23.
The new behavior will make the drain command go through all nodes even if one or more nodes failed during the drain.
For now, 7.k8s.调度器scheduler 亲和性污点
 k8s的pod的资源调度
 k8s调度器之亲和性和反亲和性/节点选择器
 关于 Kubernetes中Pod的一些笔记
 Kubernetes（k8s）亲和性调度
 K8S之节点亲和性调度