Pod Affinity

If you have the time, you must read about Pod Affinity.

Problem

I do not want to run a specific workload (sensitive-workload) along with some disruptive workloads (mysql and prometheus) within the same node. I know that these disruptive workloads have the following pod labels:

app=mysql (default namespace)
app=prometheus (monitoring namespace)

kubectl get pods -l app=mysql -n default
kubectl get pods -l app=prometheus -n monitoring

Solution:

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: sensitive-workload
  namespace: default
spec:
  template:
    metadata:
      labels:
        app: sensitive-workload
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
          - labelSelector:
              matchExpressions:
              - key: app
                operator: In
                values:
                - mysql
            topologyKey: "kubernetes.io/hostname"
          - labelSelector:
              matchExpressions:
                - key: app
                  operator: In
                  values:
                  - prometheus
            topologyKey: "kubernetes.io/hostname"
            namespaces:
              - monitoring

By default labelSelector will search within the same namespace of the workload. You can use the namespaces field to add more namespaces to look for.

Blog

Kubernetes Pod Affinity rules in a nutshell

Bryan Sazon

Pod Affinity

Problem

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