Kubernetes Nginx Ingress not finding service endpoint

I discovered what I was doing wrong. In my application definition I was using name as my selector

  selector:    matchLabels:      name: hello-world  template:    metadata:      labels:        name: hello-world

Whereas in my service I was using app

  selector:    app: hello-world

After updating my service to use app, it worked

  selector:    matchLabels:      app: hello-world  template:    metadata:      labels:        app: hello-world

Another situation when it may happen is when ingress class of the ingress controller does not match ingress class in the ingress resource manifest used for your services.

Nginx installation command, short example:

  helm install stable/nginx-ingress \  --name ${INGRESS_RELEASE_NAME} \  --namespace ${K8S_NAMESPACE} \  --set controller.scope.enabled=true \  --set controller.scope.namespace=${K8S_NAMESPACE} \  --set controller.ingressClass=${NGINX_INGRESS_CLASS}

ingress resource spec. , excerpt:

apiVersion: extensions/v1beta1kind: Ingressmetadata:  labels:  annotations:    # folowing line is not valid for K8s or Helm,     # but reflects the values must be the same    kubernetes.io/ingress.class: ${NGINX_INGRESS_CLASS}

In my case, I included an "id" directive in my Service selector that was missing from the Deployment metadata and this prevented the endpoints controller from finding the correct Pod. I expect the reverse case would also fail:

---apiVersion: v1kind: Servicemetadata:  name: some-servicespec:  ports:    - name: port-name      port: 1234      protocol: TCP  selector:    app: some-app    id: "0"  ## include in both or neither