test anti affinity of pods.

pod_anti_affinity.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    run: slam
  name: slam
spec:
  replicas: 30
  selector:
    matchLabels:
      run: slam
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        run: slam
    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchExpressions:
                - key: run #I am using the labels set on the nodes of this deployment.
                  operator: In
                  values:
                  - slam
              topologyKey: kubernetes.io/hostname
      containers:
      - image: quay.io/dcooley/simple-app:plain
        name: slam
        resources: {}
status: {}

test.md

$ kubectl get pods -o jsonpath={..spec.nodeName} | tr ' ' '\n' | sort | uniq -c
  15 ip-10-0-34-210.us-west-1.compute.internal
  15 ip-10-0-61-157.us-west-1.compute.internal