How to select multiple pod for a service in Kubernetes

Question

I want to link services to specific pod by using StatefulSets in Kubernetes as below.

• service_1 links to web-0, web-1 pod
• service_2 links to web-2, web-3 pod

I know there is a label to select specific pod

"statefulset.kubernetes.io/pod-name: web-01"

but this label seems only select one pod. Is there a way to select multiple pod?

Answer 1

If you need to point services into a portion of pods in a StatefulSet, the best practice is to create multiple StatefulSets, or use Canary Deployments with StatefulSets

If you need to know how to point a service into a StatefulSet, there is three options:

1. Create a headless service for the StatefulSet.

2. Use the service name as the hostname in the StatefulSet pod specification.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: my-statefulset
spec:
  serviceName: my-statefulset
  replicas: 3
  selector:
    matchLabels:
      app: my-statefulset
  template:
    metadata:
      labels:
        app: my-statefulset
    spec:
      hostname: my-statefulset
      subdomain: my-namespace.svc.cluster.local
      containers:
      - name: my-container
        image: my-image
        command: ["/bin/sh"]
        args: ["-c", "while true; do sleep 3600; done"]

3. Use environment variables or DNS resolution to connect to the service from within the pod.

---

To point a service to multiple pod names, there is no possible way, According to documentation:

Caution: For both equality-based and set-based conditions there is no logical OR (||) operator. Ensure your filter statements are structured accordingly