I have a Service in a Kubernetes cluster which has a label selector, several pods have this label, therefore are "connected" to the Service. Is it possible to retrieve the internal IP addresses of these pods using the Service IP?
I know that service endpoints can be retrieved in the Kubernetes CLI, however, I was wondering whether this could be achieved in Java? i.e., Nslookup.
Maybe an addition to this question would be: How do you perform a DNS query on a headless service, do you pass the service name?
Thanks,
You can get the endpoints from the API server. For example to get the IP addresses for the first endpoint returned by the API server:
$ curl -s -k -H 'Authorization: Bearer <REDACTED>' \
https://<apiserver-address>:6443/api/v1/endpoints | \
jq .items[0].subsets[0].addresses[].ipYou can also use this to retrieve the node names where your pods are running calling the above endpoint.
$ curl -s -k -H 'Authorization: Bearer <REDACTED>' \
https://<apiserver-address>:6443/api/v1/endpoints | \
jq .items[0].subsets[0].addresses[].nodeNameThis can also be done using your favorite language API like Java, Go and Python
Described here the SRV records that you can use to find the CLUSTER-IP address of your service (not your pods IP addresses). From a pod:
$ dig srv _portname._tcp.servicename.default.svc.cluster.local
...
servicename.default.svc.cluster.local. 5 IN A 10.x.x.x <== service IP
...