k8s-pod-affinity-rules

k8s-pod-affinity.yaml

...pod webserver

$ cat webserver.yaml
apiVersion: v1
kind: Pod
metadata:
  name: webserver
  labels:
     appname: "webapp"
spec:
  containers:
  - name: nginx
    image: nginx

... pod database

$ cat database.yaml
apiVersion: v1
kind: Pod
metadata:
  name: database
spec:
  affinity:
    podAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - key:  appname
            operator: In
            values:
            - "webapp"
        topologyKey: kubernetes.io/hostname
  containers:
  - name: pod-affinity
    image: mysql