18、Kubernetes 調度器 - 調度親和性

節點親和性

pod.spec.nodeAffinity

• preferredDuringSchedulingIgnoredDuringExecution：軟策略

• requiredDuringSchedulingIgnoredDuringExecution：硬策略

requiredDuringSchedulingIgnoredDuringExecution

apiVersion: v1
kind: Pod
metadata:
  name: affinity
  labels:
    app: node-affinity-pod
spec:
  containers:
  - name: with-node-affinity
    image: wangyanglinux/myapp:v1
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: NotIn
            values:
            - k8s-node02

apiVersion: v1
kind: Pod
metadata:
  name: affinity
  labels:
    app: node-affinity-pod
spec:
  containers:
  - name: with-node-affinity
    image: wangyanglinux/myapp:v1
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - k8s-node02

preferredDuringSchedulingIgnoredDuringExecution

apiVersion: v1
kind: Pod
metadata:
  name: affinity
  labels:
    app: node-affinity-pod
spec:
  containers:
  - name: with-node-affinity
    image: wangyanglinux/myapp:v1
  affinity:
    nodeAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 1
        preference:
          matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - k8s-node02

合體

apiVersion: v1
kind: Pod
metadata:
  name: affinity
  labels:
    app: node-affinity-pod
spec:
  containers:
  - name: with-node-affinity
    image: wangyanglinux/myapp:v1
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: kubernetes.io/hostname
            operator: NotIn
            values:
            - k8s-node02
      preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 1
        preference:
          matchExpressions:
          - key: kubernetes.io/hostname
            operator: In
            values:
            - k8s-node01

鍵值運算關係

• In：label 的值在某個列表中

• NotIn：label 的值不在某個列表中

• Gt：label 的值大於某個值

• Lt：label 的值小於某個值

• Exists：某個 label 存在

• DoesNotExist：某個 label 不存在

Pod 親和性

pod.spec.affinity.podAffinity/podAntiAffinity

• preferredDuringSchedulingIgnoredDuringExecution：軟策略

• requiredDuringSchedulingIgnoredDuringExecution：硬策略

apiVersion: v1
kind: Pod
metadata:
  name: node01
  labels:
    app: node01
spec:
  containers:
  - name: node01
    image: wangyanglinux/myapp:v1

apiVersion: v1
kind: Pod
metadata:
  name: pod-3
  labels:
    app: pod-3
spec:
  containers:
  - name: pod-3
    image: wangyanglinux/myapp:v1
  affinity:
    podAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - key: app
            operator: In
            values:
            - node01
        topologyKey: kubernetes.io/hostname

將app=node01改成app=node02時，就不能匹配了

apiVersion: v1
kind: Pod
metadata:
  name: pod-3
  labels:
    app: pod-3
spec:
  containers:
  - name: pod-3
    image: wangyanglinux/myapp:v1
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 1
        podAffinityTerm:
          labelSelector:
            matchExpressions:
            - key: app
              operator: In
              values:
              - node01
          topologyKey: kubernetes.io/hostname

親和性/反親和性調度策略比較如下：

調度策略	匹配標籤	操作符	拓撲域支持	調度目標
nodeAffinity	主機	In, NotIn, Exists,DoesNotExist, Gt, Lt	否	指定主機
podAffinity	POD	In, NotIn, Exists,DoesNotExist	是	POD與指定POD同一拓撲域
podAnitAffinity	POD	In, NotIn, Exists,DoesNotExist	是	POD與指定POD不在同一拓撲域