image.png

前言：
由于Affinity對(duì)pod的調(diào)度更加精細(xì)，我們?cè)谑褂弥兄饾u代替了NodeSelector?？梢苑譃閚ode親和性調(diào)度和pod親和性調(diào)度。
1）node親和性調(diào)度：不僅有NodeSelector的硬限制，而且可以在軟限制中定義權(quán)重。
2）pod親和性調(diào)度：它可以使得pod根據(jù)在節(jié)點(diǎn)上正在運(yùn)行的pod的標(biāo)簽（而不是節(jié)點(diǎn)的標(biāo)簽）進(jìn)行調(diào)度，要求對(duì)節(jié)點(diǎn)和pod兩個(gè)條件進(jìn)行匹配。

1. Node Affinity

1.1 node節(jié)點(diǎn)的預(yù)制標(biāo)簽

有一些預(yù)置的標(biāo)簽，我們可以直接使用

查看master上的標(biāo)簽

[root@DoM01 ~]# kubectl get node dom03 --show-labels
NAME    STATUS   ROLES    AGE   VERSION   LABELS
dom03   Ready    master   52d   v1.15.2   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=dom03,kubernetes.io/os=linux,node-role.kubernetes.io/master=

格式不是很友好，我們用describe看一下

[root@DoM01 ~]# kubectl describe node dom01
Name:               dom01
Roles:              master
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    kubernetes.io/arch=amd64
                    kubernetes.io/hostname=dom01
                    kubernetes.io/os=linux
                    node-role.kubernetes.io/master=
……

說明：
"beta.kubernetes.io/arch=amd64"，"beta.kubernetes.io/os=linux" 這兩個(gè)在1.18中棄用。
看名字使用，也沒什么解釋的。

1.2 自定義標(biāo)簽

1.2.1 給node增加標(biāo)簽

語法

# kubectl label node node名  鍵=值

示例

[root@DoM01 ~]# kubectl label node don01 zone=east
node/don01 labeled

驗(yàn)證
如下可見 don01 設(shè)置了標(biāo)簽 zone=east

[root@DoM01 ~]# kubectl describe node don01
Name:               don01
Roles:              <none>
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    kubernetes.io/arch=amd64
                    kubernetes.io/hostname=don01
                    kubernetes.io/os=linux
                    zone=east

1.2.2 修改label

說明：加 --overwrite參數(shù)

# kubectl label node don01 zone=south --overwrite

1.2.3 修改label

說明：刪除一個(gè)key為zone的標(biāo)簽，只需把key的后邊加一個(gè)減號(hào)即會(huì)刪除該key

# kubectl label node don01 zone-

1.3 Require

概述：
equiredDuringSchedulingIgnoredDuringExecution是硬限制，必須滿足此條件才可以調(diào)度pod到該node上（功能和nodeSelector很像）
示例

apiVersion: v1
kind: Pod
metadata:
  name: nginxtest
  namespace: test
spec:
  affinity:
     # 說明是"節(jié)點(diǎn)親和性調(diào)度"
    nodeAffinity:
      # 說明是"節(jié)點(diǎn)親和性調(diào)度"
      requiredDuringSchedulingIgnoredDuringExecution:
        #說明要選擇節(jié)點(diǎn)了
        nodeSelectorTerms:
        - matchExpressions:
          - key: zone
            operator: In
            values:
            - "east"
  containers:
    - name: nginxtest
      image: harbocto.boe.com.cn/public/nginx

創(chuàng)建并查看結(jié)果

[root@DoM01 test]# kubectl create -f nginx.yml
pod/nginxtest created
[root@DoM01 test]# kubectl get pod -n test -o wide
NAME        READY   STATUS    RESTARTS   AGE   IP             NODE    NOMINATED NODE   READINESS GATES
nginxtest   1/1     Running   0          91s   10.244.5.166   don03   <none>           <none>

說明：可以看到，pod被調(diào)度到了一個(gè)zone=east的節(jié)點(diǎn)don01上

更改調(diào)度
將yml文件修改成調(diào)度到zone=south的節(jié)點(diǎn)，然后更新pod如下

[root@DoM01 test]# kubectl apply -f nginx.yml
The Pod "nginxtest" is invalid: spec: Forbidden: pod updates may not change fields other than `spec.containers[*].image`, `spec.initContainers[*].image`, `spec.activeDeadlineSeconds` or `spec.tolerations` (only additions to existing tolerations)
  core.PodSpec{
        ……

說明：以上報(bào)錯(cuò)為了引出下邊兩個(gè)重要規(guī)則。

規(guī)則
1）親和度的值是不能直接修改的。
2）如果此時(shí)修改了node標(biāo)簽，使得節(jié)點(diǎn)不滿足要求，這個(gè)改變也將被系統(tǒng)忽略。（即pod仍會(huì)在該節(jié)點(diǎn)上運(yùn)行）

1.4 Perferred

概述
preferredDuringSchedulingIgnoredDuringExecution 是軟限制，強(qiáng)調(diào)優(yōu)先滿足制定規(guī)則，多個(gè)優(yōu)先級(jí)可以設(shè)置權(quán)重。
示例

apiVersion: v1
kind: Pod
metadata:
  name: nginxtest
  namespace: test
spec:
  affinity:
    nodeAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
        - weight: 60
          preference:
            matchExpressions:
            - key: zone
              operator: In
              values:
              - "east"
        - weight: 80
          preference:
            matchExpressions:
            - key: zone
              operator: In
              values:
              - "south"
  containers:
    - name: nginxtest
      image: harbocto.boe.com.cn/public/nginx

創(chuàng)建并查看結(jié)果

[root@DoM01 test]# kubectl create -f nginx.yml
pod/nginxtest created
[root@DoM01 test]# kubectl get pod -n test  -o wide
NAME        READY   STATUS    RESTARTS   AGE   IP             NODE    NOMINATED NODE   READINESS GATES
nginxtest   1/1     Running   0          23s   10.244.7.190   don05   <none>           <none>

說明：雖然 zone=east的權(quán)重是60，但是仍可以調(diào)度到上邊

修改east的權(quán)重為20，刪除pod再啟動(dòng)一下

[root@DoM01 test]# kubectl create -f nginx.yml
pod/nginxtest created
[root@DoM01 ~]# kubectl get pod -n test  -o wide
NAME        READY   STATUS    RESTARTS   AGE   IP            NODE    NOMINATED NODE   READINESS GATES
nginxtest   1/1     Running   0          18m   10.244.3.33   don01   <none>           <none>
[root@DoM01 ~]#

說明：可以看到此時(shí)該pod被調(diào)度到zone=south的節(jié)點(diǎn)上了，權(quán)重的作用可見一斑。

1.3 注意事項(xiàng)

如果設(shè)置了nodeSelector和nodeAffinity，則需同時(shí)滿足。
如果設(shè)置多個(gè)nodeSelectorTerms，有一個(gè)滿足即可。
如果nodeSelectorTerms下有多個(gè) matchExpressions，則必須滿足所有條件才可以。

2. Pod Affinity

說明：
根據(jù)pod1的標(biāo)簽選是否在某一組（或一個(gè)）node節(jié)點(diǎn)上部署pod2。
這一組node上用來限制親和度的標(biāo)簽的key 稱為 topologyKey。
因此pod2需要兩個(gè)標(biāo)簽來確定親和度：
(1）限制在那個(gè)范圍內(nèi)（topologyKey）。( 2）和哪個(gè)pod親和（相應(yīng)pod的標(biāo)簽）。
關(guān)于topologyKey，我們不需要指明值，因?yàn)橹灰粋€(gè)值的一組node下親和就可以了。

2.1 Pod Affinity

說明：
同樣分為
"requiredDuringSchedulingIgnoredDuringExecution"
"preferredDuringSchedulingIgnoredDuringExecution"
兩種

2.1.1 required

參照目標(biāo)pod

apiVersion: v1
kind: Pod
metadata:
  name: nginx-flag
  namespace: test
labels:
  security: "S1"
  app: "nginx-flag"
spec:       
  containers:
    - name: nginx-flag
      image: nginx

pod的親和度調(diào)度

apiVersion: v1
kind: Pod
metadata:
  name: nginxtest
  namespace: test
spec:
  affinity:
    podAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - key: security
            operator: In
            values:
            - "S1"
        topologyKey: kubernetes.io/hostname
  containers:
  - name: nginxtest
    image: harbocto.boe.com.cn/public/nginx

啟動(dòng)并查看結(jié)果

[root@DoM01 test]# kubectl create -f nginx-flag.yml
[root@DoM01 test]# kubectl create -f nginx.yml
pod/nginxtest created
[root@DoM01 test]# kubectl get pod -n test -o wide
NAME         READY   STATUS    RESTARTS   AGE   IP             NODE    NOMINATED NODE   READINESS GATES
nginx-flag   1/1     Running   1          14m   10.244.7.191   don05   <none>           <none>
nginxtest    1/1     Running   0          58s   10.244.7.192   don05   <none>           <none>

說明：可見nginxtest調(diào)度到了nginx-flag上

找不到合適節(jié)點(diǎn)
如果沒有啟動(dòng)nginx-flag而直接啟動(dòng)nginxtest，系統(tǒng)找不到合適的節(jié)點(diǎn)調(diào)度，會(huì)一直處于pending狀態(tài)。

[root@DoM01 test]# kubectl create -f nginx.yml
pod/nginxtest created
[root@DoM01 test]# kubectl get pod -n test
NAME        READY   STATUS    RESTARTS   AGE
nginxtest   0/1     Pending   0          3s

如下可見，nginx-flag啟動(dòng)之后，nginxtest被調(diào)度到了有nginx-flag的節(jié)點(diǎn)上。

[root@DoM01 test]# kubectl create -f nginx-flag.yml
pod/nginx-flag created
NAME         READY   STATUS    RESTARTS   AGE     IP             NODE    NOMINATED NODE   READINESS GATES
nginx-flag   1/1     Running   0          17s     10.244.5.169   don03   <none>           <none>
nginxtest    1/1     Running   0          2m33s   10.244.5.168   don03   <none>           <none>

2.1.2 preferred

參照目標(biāo)pod
同上
pod的親和度調(diào)度
創(chuàng)建nginx.yml文件如下：

apiVersion: v1
kind: Pod
metadata:
  name: nginxtest
  namespace: test
spec:
  affinity:
    podAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 20
        podAffinityTerm:
          labelSelector:
            matchExpressions:
            - key: security
              operator: In
              values:
              - "S1"
          topologyKey: kubernetes.io/hostname
      - weight: 80
        podAffinityTerm:
          labelSelector:
            matchExpressions:
            - key: security
              operator: In
              values:
              - "S2"
          topologyKey: kubernetes.io/hostname
  containers:
    - name: nginxtest
      image: harbocto.boe.com.cn/public/nginx

啟動(dòng)和查看

[root@DoM01 test]# kubectl create -f nginx.yml
pod/nginxtest created
[root@DoM01 test]# kubectl get pod -n test  -o wide
NAME         READY   STATUS    RESTARTS   AGE   IP            NODE    NOMINATED NODE   READINESS GATES
nginx-flag   1/1     Running   0          56s   10.244.3.34   don01   <none>           <none>
nginxtest    1/1     Running   0          8s    10.244.3.35   don01   <none>           <none>

如上，可見nginxtest被調(diào)度到了nginx-flag所在的節(jié)點(diǎn)上

親和度是相互的

測(cè)試：
再啟動(dòng)一個(gè)nginx-flag-02，lable設(shè)置為security=S2。由前邊可知，nginxtest和它的親和度是80，但是它會(huì)主動(dòng)選擇nginxtest。

apiVersion: v1
kind: Pod
metadata:
  name: nginx-flag-02
  namespace: test
  labels:
    security: "S2"
    app: "nginx-flag"
spec:
  containers:
    - name: nginx-flag-02
      image: harbocto.boe.com.cn/public/nginx

刪除nginxtest，在重新啟動(dòng)

[root@DoM01 test]# kubectl create -f nginx-flag02.yml
pod/nginx-flag-02 created
[root@DoM01 test]# kubectl get pod -n test  -o wide
NAME            READY   STATUS    RESTARTS   AGE     IP            NODE    NOMINATED NODE   READINESS GATES
nginx-flag      1/1     Running   0          3m18s   10.244.3.34   don01   <none>           <none>
nginx-flag-02   1/1     Running   0          6s      10.244.3.36   don01   <none>           <none>
nginxtest       1/1     Running   0          2m30s   10.244.3.35   don01   <none>           <none>

如上：
發(fā)現(xiàn)它們竟然會(huì)粘在一起，nginx-flag-02居然也會(huì)啟動(dòng)在（看了一下node資源，如果沒有親和度的話nginx-flag-02應(yīng)該啟動(dòng)在don03上。）

刪除ngintest，在刪除nginx-flag-02。再啟動(dòng)nginx-flag-02，果然如上邊預(yù)期被調(diào)度到了don03上。

[root@DoM01 test]# kubectl delete -n test pod nginxtest
pod "nginxtest" deleted
[root@DoM01 test]# kubectl delete -n test pod nginx-flag-02
pod "nginx-flag-02" deleted
[root@DoM01 test]# kubectl create -f nginx-flag02.yml
pod/nginx-flag-02 created
[root@DoM01 test]# kubectl get pod -n test  -o wide
NAME            READY   STATUS    RESTARTS   AGE     IP             NODE    NOMINATED NODE   READINESS GATES
nginx-flag      1/1     Running   0          5m36s   10.244.3.34    don01   <none>           <none>
nginx-flag-02   1/1     Running   0          2s      10.244.5.191   don03   <none>           <none>

測(cè)試親和度權(quán)重

[root@DoM01 test]# kubectl create -f nginx.yml
pod/nginxtest created
[root@DoM01 test]# kubectl get pod -n test -o wide
NAME            READY   STATUS    RESTARTS   AGE     IP             NODE    NOMINATED NODE   READINESS GATES
nginx-flag      1/1     Running   0          4h24m   10.244.3.34    don01   <none>           <none>
nginx-flag-02   1/1     Running   0          4h19m   10.244.5.191   don03   <none>           <none>
nginxtest       1/1     Running   0          14s     10.244.5.194   don03   <none>           <none>

說明：如上可見，nginxtest被調(diào)度到權(quán)重更高的nginx-flag-02的節(jié)點(diǎn)上了。

2.2 Pod Anti Affinity

參照pod
復(fù)制一下剛才的參照pod，把五個(gè)節(jié)點(diǎn)的四個(gè)都占了

apiVersion: v1
kind: Pod
metadata:
  name: nginx-flag-01
  namespace: test
  labels:
    security: "S1"
    app: "nginx-flag"
spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - "don01"
  containers:
    - name: nginx-flag-01
      image: harbocto.boe.com.cn/public/nginx
---
apiVersion: v1
kind: Pod
metadata:
  name: nginx-flag-02
  namespace: test
  labels:
    security: "S2"
    app: "nginx-flag"
spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - "don02"
  containers:
    - name: nginx-flag-02
      image: harbocto.boe.com.cn/public/nginx
---
apiVersion: v1
kind: Pod
metadata:
  name: nginx-flag-03
  namespace: test
  labels:
    security: "S3"
    app: "nginx-flag"
spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - "don03"
  containers:
    - name: nginx-flag-03
      image: harbocto.boe.com.cn/public/nginx
---
apiVersion: v1
kind: Pod
metadata:
  name: nginx-flag-04
  namespace: test
  labels:
    security: "S4"
    app: "nginx-flag"
spec:
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - "don04"
  containers:
    - name: nginx-flag-04
      image: harbocto.boe.com.cn/public/nginx

pod的反親和調(diào)度

apiVersion: v1
kind: Pod
metadata:
  name: nginxtest-02
  namespace: test
spec:
  affinity:
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - key: app
            operator: In
            values:
            - "nginx-flag"
        topologyKey: kubernetes.io/hostname
  containers:
  - name: nginxtest-02
    image: harbocto.boe.com.cn/public/nginx

創(chuàng)建和查看

[root@DoM01 test]# kubectl get pod -n test -o wide
NAME            READY   STATUS    RESTARTS   AGE   IP             NODE    NOMINATED NODE   READINESS GATES
nginx-flag-01   1/1     Running   0          15m   10.244.3.38    don01   <none>           <none>
nginx-flag-02   1/1     Running   0          15m   10.244.4.35    don02   <none>           <none>
nginx-flag-03   1/1     Running   0          15m   10.244.5.201   don03   <none>           <none>
nginx-flag-04   1/1     Running   0          15m   10.244.6.27    don04   <none>           <none>
nginxtest-02    1/1     Running   0          14m   10.244.7.210   don05   <none>           <none>

如上可見，nginxtest-02被調(diào)度到最后剩下的一個(gè)節(jié)點(diǎn)上了

2.3 注意事項(xiàng)

topology
1）反親和性 requiredDuringScheduling 中topologyKey 不能為空
2）反親和性 preferredDuringScheduling 中topologyKey 為空，則被認(rèn)為是如下的組合：
kubernetes.io/hostname
failure-domain.beta.kubernetes.io/zone
failure-domain.beta.kubernetes.io/region
3）如果admission controller 設(shè)置了LimitPodHardAntiAffinityTopology ，則互斥性被限制在 kubernetes.io/hostname
namespace限制
1）位置：和topologyKey同級(jí)
2）未定義namespace：表示和參照目標(biāo)的pod相同
3）設(shè)置為空：表示所有namespace

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pod的親和度調(diào)度

pod的親和度調(diào)度

1. Node Affinity

1.1 node節(jié)點(diǎn)的預(yù)制標(biāo)簽

1.2 自定義標(biāo)簽

1.2.1 給node增加標(biāo)簽

1.2.2 修改label

1.2.3 修改label

1.3 Require

1.4 Perferred

1.3 注意事項(xiàng)

2. Pod Affinity

2.1 Pod Affinity

2.1.1 required

2.1.2 preferred

2.2 Pod Anti Affinity

2.3 注意事項(xiàng)

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pod的親和度調(diào)度

1. Node Affinity

1.1 node節(jié)點(diǎn)的預(yù)制標(biāo)簽

1.2 自定義標(biāo)簽

1.2.1 給node增加標(biāo)簽

1.2.2 修改label

1.2.3 修改label

1.3 Require

1.4 Perferred

1.3 注意事項(xiàng)

2. Pod Affinity

2.1 Pod Affinity

2.1.1 required

2.1.2 preferred

2.2 Pod Anti Affinity

2.3 注意事項(xiàng)

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容

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