How to make kubernetes pod have access to PostgreSQL Pod

Question

I am trying local Kubernetes(Docker-on-mac), and trying to submit a spark job. The spark job, connects with a PostgreSQL database and do some calculations.

The PostgreSQL is running on my Kube and since I have published it, I can access it from the host via localhost:5432. However, when the spark application is trying to connect to PostgreSQL, it throws

Exception in thread "main" org.postgresql.util.PSQLException: Connection to localhost:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.

kubectl cluster-info

Kubernetes master is running at https://kubernetes.docker.internal:6443
KubeDNS is running at https://kubernetes.docker.internal:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

kubectl get service postgresql-published

kubectl describe service spark-store-1588217023181-driver-svc

Name:              spark-store-1588217023181-driver-svc
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          spark-app-selector=spark-533ecb8556b6439eb938d487cc77c330,spark-role=driver
Type:              ClusterIP
IP:                None
Port:              driver-rpc-port  7078/TCP
TargetPort:        7078/TCP
Endpoints:         <none>
Port:              blockmanager  7079/TCP
TargetPort:        7079/TCP
Endpoints:         <none>
Session Affinity:  None

How can I make my spark job, have access to PostgreSQL service?

Answer 1

NAME                  TYPE           CLUSTER-IP      EXTERNAL-IP   PORTS
postgresql-published  LoadBalancer   10.106.15.112   localhost     5432:31277

Means that the service shall be accessible within the cluster at 10.106.15.112:5432 , postgresql-published:5432 and externally at localhost:31277.

Please note that for the Pod the localhost is the Pod itself. In this very case localhost looks ambiguous. However that is how the expose works.