K
Q

Can't ping other pods by hostname on minikube

10/5/2018

I have a statefulSet with two replicas. It's headless service name is "gov-svc" It's ->

  1. .metadata.name: sts
  2. .metadata.namespace: default
  3. .spec.serviceName: gov-svc
  4. .spec.template.spec.subdomain: gov-svc
  5. .spec.replicas: 2

Before running statefulSet

kubectl get pods --all-namespaces
NAMESPACE     NAME                                    READY   STATUS             RESTARTS   AGE
kube-system   coredns-99b9bb8bd-qdnsb                 1/1     Running            0          4h
kube-system   etcd-minikube                           1/1     Running            0          4h
kube-system   kube-addon-manager-minikube             1/1     Running            0          4h
kube-system   kube-apiserver-minikube                 1/1     Running            0          4h
kube-system   kube-controller-manager-minikube        1/1     Running            1          4h
kube-system   kube-proxy-b9np6                        1/1     Running            0          4h
kube-system   kube-scheduler-minikube                 1/1     Running            0          4h
kube-system   kubernetes-dashboard-7db4dc666b-bsk8k   1/1     Running            0          4h
kube-system   storage-provisioner

After running both of the pods of this statefulSet, from pod sts-0, ping results:

$ ping  sts-0.gov-svc.default.svc.cluster.local
PING sts-0.gov-svc.default.svc.cluster.local (172.17.0.11): 56 data bytes
64 bytes from 172.17.0.11: seq=0 ttl=64 time=0.051 ms
64 bytes from 172.17.0.11: seq=1 ttl=64 time=0.444 ms
^C
--- redis-cluster-exp-0-0.redis-cluster-exp.default.svc.cluster.local ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.051/0.247/0.444 ms

But when I try to ping sts-1 from sts-0, it says:

$ ping sts-1.gov-svc.default.svc.cluster.local
ping: bad address 'sts-1.gov-svc.default.svc.cluster.local'

I need to ping other pods successfully by hostname. How can I do it?

-- Shudipta Sharma
kube-dns
kubernetes
kubernetes-pod
kubernetes-statefulset
minikube

Similar Questions

Kubernetes google cloud composer with gitlab ci yaml file
Is running spark on kubernetes still experimental?
Kubernetes refer docker images from single node and create containers in any node
Helm with AKS and ARM Templates
nginx ingress rate limiting
helm chart : strings concatenation

1 Answer

10/5/2018

You need to create headless service to be able to ping replicas from each to other within a StatefulSet. Something like:

apiVersion: v1
kind: Service
metadata:
  name: gov-svc-headless
  labels:
    your_label: your_value
spec:
  selector:
    your_label: your_value
  ports:
  - port: your_port
    name: transport
    protocol: TCP
  clusterIP: None <---

Note:

With selectors For headless services that define selectors, the endpoints controller creates Endpoints records in the API, and modifies the DNS configuration to return A records (addresses) that point directly to the Pods backing the Service.

Note:

or headless services that do not define selectors, the endpoints controller does not create Endpoints records. However, the DNS system looks for and configures either:

CNAME records for ExternalName-type services. A records for any Endpoints that share a name with the service, for all other types.

More info: https://kubernetes.io/docs/concepts/services-networking/service/#headless-services

-- Konstantin Vustin
Source: StackOverflow