首页Kubernetes

# K8s 亲和力 Affinity

Pod 和节点之间的关系：

  • 某些 Pod 优先选择有 ssd=true 标签的节点，如果没有在考虑部署到其它节点；
  • 某些 Pod 需要部署在 ssd=true 和 type=physical 的节点上，但是优先部署在 ssd=true 的节点上。

Pod 和 Pod 之间的关系：

  • 同一个应用的 Pod 不同的副本或者同一个项目的应用尽量或必须不部署在同一个节点或者符合某个标签的一类节点上或者不同的区域；
  • 相互依赖的两个 Pod 尽量或必须部署在同一个节点上或者同一个域内。

# 1. Affinity 分类

1.png

# 2. 节点亲和力配置详解

# 2.1 硬亲和力 required
# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    app: nginx-deploy
  annotations:
    app: nginx-deploy
  namespace: default
spec:
  selector:
    matchLabels:
      app: nginx-deploy
  replicas: 5
  template:
    metadata:
      labels:
        app: nginx-deploy
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                  - key: kubernetes.io/hostname
                    operator: In
                    values:
                      - k8s-node01
                      - k8s-node02
      restartPolicy: Always
      containers:
        - name: nginx-deploy
          image: nginx:latest
          imagePullPolicy: IfNotPresent
          resources:
            limits:
              memory: 1024Mi
              cpu: 1
            requests:
              memory: 128Mi
              cpu: 100m
  • requiredDuringSchedulingIgnoredDuringExecution：硬亲和力配置
  • nodeSelectorTerms：节点选择器配置，可以配置多个 matchExpressions（满足其一即可）
  • matchExpressions：matchExpressions 下可以配置多个 key、values（都需要满足），其中 values 可以配置多个（满足其一即可）
  • operator：
    • IN 相当于 key = value 的形式，NotIn 相当于 key!=value 的形式 (反亲和力)
    • Exists: 节点存在 label 的 key 为指定的值即可，不能配置 values 字段
    • DoesNotExist: 节点不存在 label 的 key 为指定的值即可，不能配置 values 字段
    • Gt：大于 value 指定的值
    • Lt：小于 value 指定的值
# 2.2 软亲和力 preferred
# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    app: nginx-deploy
  namespace: default
spec:
  selector:
    matchLabels:
      app: nginx-deploy
  replicas: 6
  template:
    metadata:
      labels:
        app: nginx-deploy
    spec:
      affinity:
        nodeAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
            - weight: 100
              preference:
                matchExpressions:
                  - key: ssd
                    operator: In
                    values:
                      - 'true'
            - weight: 50
              preference:
                matchExpressions:
                  - key: kubernetes.io/hostname
                    operator: In
                    values:
                      - k8s-master01
      restartPolicy: Always
      containers:
        - name: nginx-deploy
          image: nginx
          imagePullPolicy: IfNotPresent
          resources:
            limits:
              memory: 1024Mi
              cpu: 1
            requests:
              memory: 128Mi
              cpu: 100m
  • preferredDuringSchedulingIgnoredDuringExecution：软亲和力配置
  • weight：软亲和力的权重，权重越高优先级越大，范围 1-100
  • matchExpressions：matchExpressions 下可以配置多个 key、values（都需要满足），其中 values 可以配置多个（满足其一即可）
  • operator：
    • IN 相当于 key = value 的形式，NotIn 相当于 key!=value 的形式 (反亲和力)
    • Exists: 节点存在 label 的 key 为指定的值即可，不能配置 values 字段
    • DoesNotExist: 节点不存在 label 的 key 为指定的值即可，不能配置 values 字段
    • Gt：大于 value 指定的值
    • Lt：小于 value 指定的值

# 3. Pod 亲和力详解

[root@k8s-master01 ~]# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx-deploy
  name: nginx-deploy
spec:
  replicas: 4
  selector:
    matchLabels:
      app: nginx-deploy
  template:
    metadata:
      labels:
        app: nginx-deploy
    spec:
      affinity:              
        podAntiAffinity:   #pod 硬反亲和力
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - nginx-deploy
            topologyKey: kubernetes.io/hostname
        podAntiAffinity:       #pod 软反亲和力
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchExpressions:
                - key: app
                  operator: In
                  values:
                  - nginx-deploy
              namespaces:     #和哪个命名空间的 Pod 进行匹配，为空为当前命名空间
              - default
              topologyKey: kubernetes.io/hostname

  • labelSelector：Pod 选择器配置，可以配置多个

  • matchExpressions：matchExpressions 下可以配置多个 key、values（都需要满足），其中 values 可以配置多个（满足其一即可）

  • topologyKey：匹配的拓扑域的 key，也就是节点上 label 的 key，key 和 value 相同的为同一个域，可以用于标注不同的机房和地区

  • Namespaces: 和哪个命名空间的 Pod 进行匹配，为空为当前命名空间

  • operator：配置和节点亲和力一致，但是没有 Gt 和 Lt

    • IN 相当于 key = value 的形式；

    • Exists: 节点存在 label 的 key 为指定的值即可，不能配置 values 字段；

    • DoesNotExist: 节点不存在 label 的 key 为指定的值即可，不能配置 values 字段

# 4. 节点亲和力配置示例

Pod 尽量部署在 ssd=true 和 type=physical 的节点上，但是优先部署在 ssd=true 的节点上，不能部署 label 为 gpu=true 的节点。

[root@k8s-master01 ~]# kubectl label nodes k8s-node01 ssd=true
[root@k8s-master01 ~]# kubectl label nodes k8s-master01 ssd=true
[root@k8s-master01 ~]# kubectl label nodes k8s-master01 gpu=true
[root@k8s-master01 ~]# kubectl label nodes k8s-node02 type=physical
[root@k8s-master01 ~]# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    app: nginx-deploy
  annotations:
    app: nginx-deploy
  namespace: default
spec:
  selector:
    matchLabels:
      app: nginx-deploy
  replicas: 5
  template:
    metadata:
      labels:
        app: nginx-deploy
      annotations:
        app: nginx-deploy
    spec:
      affinity:
        nodeAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
            - weight: 100
              preference:
                matchExpressions:
                  - key: ssd
                    operator: In
                    values:
                      - 'true'
                  - key: gpu
                    operator: NotIn
                    values:
                      - 'true'
            - weight: 50
              preference:
                matchExpressions:
                  - key: type
                    operator: In
                    values:
                      - physical
      restartPolicy: Always
      containers:
        - name: nginx-deploy
          image: nginx
          imagePullPolicy: IfNotPresent
          resources:
            limits:
              memory: 1024Mi
              cpu: 1
            requests:
              memory: 128Mi
              cpu: 100m
          volumeMounts:
          - name: tz-config
            mountPath: /usr/share/zoneinfo/Asia/Shanghai
          - name: tz-config
            mountPath: /etc/localtime
          - name: timezone
            mountPath: /etc/timezone
      volumes:
      - name: tz-config
        hostPath:
          path: /usr/share/zoneinfo/Asia/Shanghai
          type: ""
      - name: timezone
        hostPath:
          path: /etc/timezone
          type: ""
[root@k8s-master01 ~]# kubectl apply -f nginx-deploy.yaml 
[root@k8s-master01 ~]# kubectl get pods -o wide
NAME                          READY   STATUS    RESTARTS   AGE   IP              NODE         NOMINATED NODE   READINESS GATES
nginx-deploy-7d65fbdf-2b4jr   1/1     Running   0          5s    172.16.85.236   k8s-node01   <none>           <none>
nginx-deploy-7d65fbdf-jjzwr   1/1     Running   0          5s    172.16.58.251   k8s-node02   <none>           <none>
nginx-deploy-7d65fbdf-kx5lm   1/1     Running   0          5s    172.16.85.237   k8s-node01   <none>           <none>
nginx-deploy-7d65fbdf-lrmcg   1/1     Running   0          5s    172.16.85.238   k8s-node01   <none>           <none>
nginx-deploy-7d65fbdf-n6mlp   1/1     Running   0          5s    172.16.58.250   k8s-node02   <none>           <none>
# 5. Pod 亲和力、反亲和力配置示例
# 5.1 Pod 反亲和力 required
同一个应用部署在不同的宿主机
#1. 节点存在污点 pod 无法调度至该节点
# kubectl describe nodes|grep -i taint
Taints:             <none>
Taints:             <none>
Taints:             <none>
Taints:             <none>
Taints:             <none>
#2.pod 反亲和力 required
# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    app: nginx-deploy
  namespace: default
spec:
  selector:
    matchLabels:
      app: nginx-deploy
  replicas: 5
  template:
    metadata:
      labels:
        app: nginx-deploy
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            - labelSelector:
                matchExpressions:
                  - key: app
                    operator: In
                    values:
                      - nginx-deploy
              topologyKey: kubernetes.io/hostname
      restartPolicy: Always
      containers:
        - name: nginx-deploy
          image: nginx
          imagePullPolicy: IfNotPresent
          resources:
            limits:
              memory: 1024Mi
              cpu: 1
            requests:
              memory: 128Mi
              cpu: 100m
          volumeMounts:
          - name: tz-config
            mountPath: /usr/share/zoneinfo/Asia/Shanghai
          - name: tz-config
            mountPath: /etc/localtime
          - name: timezone
            mountPath: /etc/timezone
      volumes:
      - name: tz-config
        hostPath:
          path: /usr/share/zoneinfo/Asia/Shanghai
          type: ""
      - name: timezone
        hostPath:
          path: /etc/timezone
          type: ""
#3. 部署 deployment
[root@k8s-master01 ~]# kubectl apply -f nginx-deploy.yaml 
[root@k8s-master01 ~]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP               NODE           NOMINATED NODE   READINESS GATES
nginx-deploy-5787887b6f-4654b   1/1     Running   0          4s    172.16.85.234    k8s-node01     <none>           <none>
nginx-deploy-5787887b6f-8mq7s   1/1     Running   0          4s    172.16.122.152   k8s-master02   <none>           <none>
nginx-deploy-5787887b6f-fdkft   1/1     Running   0          4s    172.16.58.247    k8s-node02     <none>           <none>
nginx-deploy-5787887b6f-jzcmd   1/1     Running   0          4s    172.16.32.152    k8s-master01   <none>           <none>
nginx-deploy-5787887b6f-qdq9g   1/1     Running   0          4s    172.16.195.14    k8s-master03   <none>           <none>
#4. 将副本扩成 6 个，由于 K8s 集群只有 5 个节点，即 5 个 topologyKey（拓扑域），每个域只能有一个副本，所以有一个 pod 会 pending
[root@k8s-master01 ~]# kubectl scale deploy nginx-deploy --replicas=6 
[root@k8s-master01 ~]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE     IP               NODE           NOMINATED NODE   READINESS GATES
nginx-deploy-5787887b6f-4654b   1/1     Running   0          4m44s   172.16.85.234    k8s-node01     <none>           <none>
nginx-deploy-5787887b6f-8mq7s   1/1     Running   0          4m44s   172.16.122.152   k8s-master02   <none>           <none>
nginx-deploy-5787887b6f-fdkft   1/1     Running   0          4m44s   172.16.58.247    k8s-node02     <none>           <none>
nginx-deploy-5787887b6f-jzcmd   1/1     Running   0          4m44s   172.16.32.152    k8s-master01   <none>           <none>
nginx-deploy-5787887b6f-qdq9g   1/1     Running   0          4m44s   172.16.195.14    k8s-master03   <none>           <none>
nginx-deploy-5787887b6f-sztm7   0/1     Pending   0          9s      <none>           <none>         <none>           <none>
[root@k8s-master01 ~]# kubectl describe pods nginx-deploy-5787887b6f-sztm7
...
Events:
  Type     Reason            Age   From               Message
  ----     ------            ----  ----               -------
  Warning  FailedScheduling  102s  default-scheduler  0/5 nodes are available: 5 node(s) didn't match pod anti-affinity rules. preemption: 0/5 nodes are available: 5 No preemption victims found for incoming pod.
将副本扩成 6 个，有一个会 pending 状态，原因 K8s 集群只有 5 个节点，即 5 个 topologyKey（拓扑域），每个拓扑域只能有一个副本，所以有一个 pod 会 pending。
topologyKey：匹配的拓扑域的 key，也就是节点上 label 的 key，key 和 value 相同的为同一个域，可以用于标注不同的机房和地区。
# 5.2 Pod 反亲和力 preferred
同一个应用尽量部署在不同的宿主机
#1. 节点存在污点 pod 无法调度至该节点
# kubectl describe nodes|grep -i taint
Taints:             <none>
Taints:             <none>
Taints:             <none>
Taints:             <none>
Taints:             <none>
#2.pod 反亲和力 preferred
# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deploy
  labels:
    app: nginx-deploy
  namespace: default
spec:
  selector:
    matchLabels:
      app: nginx-deploy
  replicas: 6
  template:
    metadata:
      labels:
        app: nginx-deploy
    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
            - podAffinityTerm:
                labelSelector:
                  matchExpressions:
                    - key: app
                      operator: In
                      values:
                        - nginx-deploy
                topologyKey: kubernetes.io/hostname
              weight: 100
      restartPolicy: Always
      containers:
        - name: nginx-deploy
          image: nginx
          imagePullPolicy: IfNotPresent
          resources:
            limits:
              memory: 1024Mi
              cpu: 1
            requests:
              memory: 128Mi
              cpu: 100m
          volumeMounts:
          - name: tz-config
            mountPath: /usr/share/zoneinfo/Asia/Shanghai
          - name: tz-config
            mountPath: /etc/localtime
          - name: timezone
            mountPath: /etc/timezone
      volumes:
      - name: tz-config
        hostPath:
          path: /usr/share/zoneinfo/Asia/Shanghai
          type: ""
      - name: timezone
        hostPath:
          path: /etc/timezone
          type: ""
#3. 部署 deployment
[root@k8s-master01 ~]# kubectl apply -f nginx-deploy.yaml 
[root@k8s-master01 ~]# kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP               NODE           NOMINATED NODE   READINESS GATES
nginx-deploy-7c47567b79-97qs5   1/1     Running   0          6s    172.16.122.153   k8s-master02   <none>           <none>
nginx-deploy-7c47567b79-g49h4   1/1     Running   0          6s    172.16.85.235    k8s-node01     <none>           <none>
nginx-deploy-7c47567b79-g5n2s   1/1     Running   0          6s    172.16.58.248    k8s-node02     <none>           <none>
nginx-deploy-7c47567b79-g5v5b   1/1     Running   0          6s    172.16.195.15    k8s-master03   <none>           <none>
nginx-deploy-7c47567b79-pjwws   1/1     Running   0          6s    172.16.58.249    k8s-node02     <none>           <none>
nginx-deploy-7c47567b79-q2hn5   1/1     Running   0          6s    172.16.32.153    k8s-master01   <none>           <none>
# 5.3 Pod 亲和力 required
同一个应用必须部署在同一个宿主机
[root@k8s-master01 ~]# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx-deploy
  name: nginx-deploy
spec:
  replicas: 8
  selector:
    matchLabels:
      app: nginx-deploy
  template:
    metadata:
      labels:
        app: nginx-deploy
    spec:
      affinity:              
        podAffinity:   #pod 硬亲和力
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - nginx-deploy
            topologyKey: kubernetes.io/hostname
      containers:
      - image: nginx
        name: nginx
        volumeMounts:
        - name: timezone
          mountPath: /etc/timezone
        - name: tz-config
          mountPath: /usr/share/zoneinfo/Asia/Shanghai
        - name: tz-config
          mountPath: /etc/localtime
      volumes:
      - name: timezone
        hostPath:
          path: /etc/timezone
          type: File
      - name: tz-config
        hostPath:
          path: /usr/share/zoneinfo/Asia/Shanghai
          type: File
[root@k8s-master01 ~]# kubectl apply -f nginx-deploy.yaml 
[root@k8s-master01 ~]# kubectl get pods -o wide
NAME                           READY   STATUS    RESTARTS   AGE   IP              NODE         NOMINATED NODE   READINESS GATES
nginx-deploy-dbcc4d65c-2sthn   1/1     Running   0          12s   172.16.58.255   k8s-node02   <none>           <none>
nginx-deploy-dbcc4d65c-78nxf   1/1     Running   0          12s   172.16.58.197   k8s-node02   <none>           <none>
nginx-deploy-dbcc4d65c-82ssq   1/1     Running   0          12s   172.16.58.194   k8s-node02   <none>           <none>
nginx-deploy-dbcc4d65c-986cb   1/1     Running   0          12s   172.16.58.254   k8s-node02   <none>           <none>
nginx-deploy-dbcc4d65c-9rnt7   1/1     Running   0          12s   172.16.58.252   k8s-node02   <none>           <none>
nginx-deploy-dbcc4d65c-knm8q   1/1     Running   0          12s   172.16.58.195   k8s-node02   <none>           <none>
nginx-deploy-dbcc4d65c-kx56f   1/1     Running   0          12s   172.16.58.253   k8s-node02   <none>           <none>
nginx-deploy-dbcc4d65c-sqlhf   1/1     Running   0          12s   172.16.58.198   k8s-node02   <none>           <none>
# 5.4 Pod 亲和力 preferre
同一个应用尽量部署在同一个宿主机
# cat nginx-deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx-deploy
  name: nginx-deploy
spec:
  replicas: 20
  selector:
    matchLabels:
      app: nginx-deploy
  template:
    metadata:
      labels:
        app: nginx-deploy
    spec:
      affinity:              
        podAffinity:       #pod 软亲和力
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchExpressions:
                - key: app
                  operator: In
                  values:
                  - nginx-deploy
              namespaces:     #和哪个命名空间的 Pod 进行匹配，为空为当前命名空间
              - default
              topologyKey: kubernetes.io/hostname
      containers:
      - image: nginx
        name: nginx
        volumeMounts:
        - name: timezone
          mountPath: /etc/timezone
        - name: tz-config
          mountPath: /usr/share/zoneinfo/Asia/Shanghai
        - name: tz-config
          mountPath: /etc/localtime
      volumes:
      - name: timezone
        hostPath:
          path: /etc/timezone
          type: File
      - name: tz-config
        hostPath:
          path: /usr/share/zoneinfo/Asia/Shanghai
          type: File
本文出自于：https://edu.51cto.com/course/23845.html
此文章已被阅读次数:正在加载...更新于
请我喝[茶]~(￣▽￣)~*
Xu Yong 微信支付
微信支付
Xu Yong 支付宝
支付宝