针对对象为Pod，目的是实现，新建Pod和目标Pod调度到一起，在同一个Node上。

示例：
 

root@k8s-master:/home/vagrant# cat pod.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: testpod01
  labels:
    app: myapp01
    env: test1
spec:
  containers:
  - name: testpod01
    image: nginx:1.23.2
    imagePullPolicy: IfNotPresent

root@k8s-master:/home/vagrant# cat pod2.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: testpod02
  labels:
    app: myapp02
    env: test2
spec:
  affinity:
    podAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:  ##必须满足下面匹配规则
      - labelSelector:
          matchExpressions:
          - key: app
            operator: In  
            values:
            - myapp01  ## app=myapp01, 上面的Pod是符合要求的
        topologyKey: "kubernetes.io/hostname"
  containers:
  - name: testpod02
    image: redis:6.2
    imagePullPolicy: IfNotPresent
root@k8s-master:/home/vagrant# kubectl create -f pod.yaml
root@k8s-master:/home/vagrant# kubectl create -f pod2.yaml 

root@k8s-master:/home/vagrant# kubectl get pods --show-labels -o wide
NAME            READY   STATUS    RESTARTS   AGE     IP              NODE          NOMINATED NODE   READINESS GATES   LABELS
node-affinity   1/1     Running   0          26m     172.16.126.2    k8s-worker2   <none>           <none>            <none>
testpod01       1/1     Running   0          8m15s   172.16.194.65   k8s-worker1   <none>           <none>            app=myapp01,env=test1
testpod02       1/1     Running   0          2m20s   172.16.194.66   k8s-worker1   <none>           <none>            app=myapp02,env=test2