Pod节点亲和性和反亲和性

podaffinity：pod节点亲和性指的是pod会被调度到更趋近与哪个pod或哪类pod。

podunaffinity：pod节点反亲和性指的是pod会被调度到远离哪个pod或哪类pod

1.  Pod节点亲和性

requiredDuringSchedulingIgnoredDuringExecution： 硬亲和性

preferredDuringSchedulingIgnoredDuringExecution：软亲和性

vi pod-required-affinity-demo-1.yaml 
apiVersion: v1
kind: Pod
metadata:name: nginxlabels:app: nginxtier: monitor
spec:containers:- name: nginximage: 172.16.80.140/nginx/nginx:1.26imagePullPolicy: IfNotPresent
kubectl apply -f pod-required-affinity-demo-1.yaml 
kubectl get pods -owide

vi pod-required-affinity-demo-2.yaml 
kind: Pod
metadata:name: busyboxlabels:app: backendtier: db
spec:containers:- name: busyboximage: 172.16.80.140/busybox/busybox:latestimagePullPolicy: IfNotPresentcommand: ["sh","-c","sleep 3600"]affinity:podAffinity:requiredDuringSchedulingIgnoredDuringExecution:- labelSelector:matchExpressions:- {key: app, operator: In, values: ["nginx"]}topologyKey: kubernetes.io/hostname

以上可以看出，第二个pod（busybox）由于设置了硬亲和性，需要和具有app=nginx的标签的pod在一起，所以也被创 建到了node01上

Pod节点反亲和性

vi pod-required-affinity-demo-3.yaml 
kind: Pod
metadata:name: busybox1labels:app: backend1tier: db
spec:containers:- name: busybox1image: 172.16.80.140/busybox/busybox:latestimagePullPolicy: IfNotPresentcommand: ["sh","-c","sleep 3600"]affinity:podAntiAffinity:requiredDuringSchedulingIgnoredDuringExecution:- labelSelector:matchExpressions:- {key: app, operator: In, values: ["nginx"]}topologyKey: kubernetes.io/hostname

以上可以看出，第三个pod（backend）设置了pod发亲和性，和匹配的pod创建在了不同的node上

vi pod-required-affinity-demo-4.yaml
apiVersion: v1
kind: Pod
metadata:name: busybox2labels:app: backendtier: db
spec:containers:- name: busybox2image: 172.16.80.140/busybox/busybox:latestimagePullPolicy: IfNotPresentcommand: ["sh","-c","sleep 3600"]affinity:podAntiAffinity:requiredDuringSchedulingIgnoredDuringExecution:- labelSelector:matchExpressions:- {key: app, operator: In, values: ["nginx"]}topologyKey: kubernetes.io/hostname- labelSelector:matchExpressions:- {key: tier, operator: In, values: ["db"]}topologyKey: kubernetes.io/hostname

以上可以看出，因为busybox2的反亲和性，导致没有pod符合条件，只能是pending状态