Connection refused when trying to access a kubernetes pod via kubernetes DNS

What is the difference when accessing a port via k8s-dns?

When you call a Pod IP address, you directly connect to a pod, not to the service.

When you call to DNS name of your service, it resolves to a Service IP address, which forward your request to actual pods using Selectors as a filter to find a destination, so it is 2 different ways of how to access pods.

Also, you cal call Service IP address directly instead of using DNS, it will works the same way. Moreover, Service IP address, unlike Pod IPs, is static, so you can use it all the time if you want.

For in-cluster communication you are using ClusterIP service mode, which is default and you set it, so everything is OK here.

Current endpoints where your service forwards requests you can get by kubectl get service $servicename -o wide in an "endpoint" column.

What about your current problems with connection, I can recommend you:

• Check endpoint of your service (there should be one or more IP addresses of pods),

• Set targetPort parameter for each of service ports, e.g:

  apiVersion: v1kind: Servicemetadata:  labels:    service: hadoop  name: hadoopspec:  ports:  - name: hadoop    port: 9000    targetPort: 9000 # here is  - name: ssh    port: 22    targetPort: 22 # here is  - name: hadoop-ui    port: 50070    targetPort: 50070 # here is  selector:    service: hadoop  type: ClusterIP

P.S. Here is a nice topic with explanation about how Service works. Also, you can check official documentation.