Service selector

service_selector.yaml

apiVersion: v1
kind: Pod
metadata:
  name: job1
  labels:
    job-name: "job1"
    job-index: "0"
spec:
  hostNetwork: true
  containers:
  - name: job1
    image: httpd:2
---
apiVersion: v1
kind: Pod
metadata:
  name: job2
  labels:
    job-name: "job2"
    job-index: "0"
spec:
  hostNetwork: true
  containers:
  - name: job2
    image: httpd:2
---
apiVersion: v1
kind: Service
metadata:
  name: service-good
spec:
  selector:
    job-name: "job1"
    job-index: "0"
  ports:
    - protocol: TCP
      port: 80
      targetPort: 9376
---
apiVersion: v1
kind: Service
metadata:
  name: service-wrong
spec:
  selector:
    job-index: "0"
  ports:
    - protocol: TCP
      port: 80
      targetPort: 9376

When applying the manifest, we can observe that the service-wrong gets the endpoints from both pods

 kubectl get endpoints
NAME            ENDPOINTS                           AGE
kubernetes      10.128.0.13:443                     2d22h
service-good    10.128.0.53:9376                    12s
service-wrong   10.128.0.51:9376,10.128.0.53:9376   12s