Kubectl : Could not resolve host

I created one node and I'm running microk8s. I created one Pod and 3 replicasets. I can access trought Cluster IP. But I don't know how to access through the name... Please help me. I'm new in Kubenetes.

I create

microk8s kubectl create deployment httpenv --image bretfisher/httpenv

Scale

microk8s kubectl scale deployment/httpenv --replicas=3

Expose

microk8s kubectl expose deployment/httpenv --port 8888

Show Info

microk8s kubectl get all

NAME                          READY   STATUS    RESTARTS   AGE
pod/httpenv-bd844d85f-9xk9l   1/1     Running   0          18m
pod/httpenv-bd844d85f-jf85j   1/1     Running   0          18m
pod/httpenv-bd844d85f-p5kzg   1/1     Running   0          18m

NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
service/httpenv      ClusterIP   10.152.183.91   <none>        8888/TCP   13m
service/kubernetes   ClusterIP   10.152.183.1    <none>        443/TCP    24h

NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/httpenv   3/3     3            3           18m

NAME                                DESIRED   CURRENT   READY   AGE
replicaset.apps/httpenv-bd844d85f   3         3         3       18m

Try to access

From node :

curl -i 10.152.183.91:8888

   HTTP/1.1 200 OK

curl -i httpenv:8888

   curl: (6) Could not resolve host: httpenv

Solution

You can access the service in 3 ways, i just ran your example in my own microk8s cluster.

Port forward traffic from 8888 to you localhost on any port(ex: i have forwarded to 8888).
If you want to access the service from within the cluster, you can access the service from any pod running in your cluster(security issue though, can be handled using policies etc).
You can conver the service from type: ClusterIP to NodePort

According to the deployment you have given above, which i ran on my local, below are the pods running. In the port-forward command below, we are routing all the traffic from microk8s cluster on port 8888 to your localhost 8888. You can then use your browser and navigate to http://localhost:8888, you will see the output there.

k get po 
httpenv-6fdc8554fb-j9q65   1/1     Running   0          14m
httpenv-6fdc8554fb-4fzr8   1/1     Running   0          14m
httpenv-6fdc8554fb-bsxgw   1/1     Running   0          14m

k port-forward httpenv-6fdc8554fb-j9q65 8888:8888 &

curl localhost:8888
Handling connection for 8888
{"HOME":"/root","HOSTNAME":"httpenv-6fdc8554fb-j9q65","KUBERNETES_PORT":"tcp://10.152.183.1:443","KUBERNETES_PORT_443_TCP":"tcp://10.152.183.1:443","KUBERNETES_PORT_443_TCP_ADDR":"10.152.183.1","KUBERNETES_PORT_443_TCP_PORT":"443","KUBERNETES_PORT_443_TCP_PROTO":"tcp","KUBERNETES_SERVICE_HOST":"10.152.183.1","KUBERNETES_SERVICE_PORT":"443","KUBERNETES_SERVICE_PORT_HTTPS":"443","PATH":"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"}%

To access the service within your microk8s cluster, we will run a simple busybox container.

k run -i --tty bb7 --image=busybox -- sh 
# curl  http://httpenv:8888
{"HOME":"/root","HOSTNAME":"httpenv-6fdc8554fb-bsxgw","KUBERNETES_PORT":"tcp://10.152.183.1:443","KUBERNETES_PORT_443_TCP":"tcp://10.152.183.1:443","KUBERNETES_PORT_443_TCP_ADDR":"10.152.183.1","KUBERNETES_PORT_443_TCP_PORT":"443","KUBERNETES_PORT_443_TCP_PROTO":"tcp","KUBERNETES_SERVICE_HOST":"10.152.183.1","KUBERNETES_SERVICE_PORT":"443","KUBERNETES_SERVICE_PORT_HTTPS":"443","PATH":"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"}#

option 3 is to change the service type from "ClusterIP" to "NodePort" and you can access the service outside of the microk8s cluster. Get your local-ip using ifconfig command and curl the node port.

forex: curl http://local-ip:31223

apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2021-11-03T09:55:20Z"
  labels:
    app: httpenv
  name: httpenv
  namespace: default
  resourceVersion: "2013136"
  selfLink: /api/v1/namespaces/default/services/httpenv
  uid: 908f4bbd-fef2-4435-b8c4-a80796e03b13
spec:
  clusterIP: 10.152.183.170
  clusterIPs:
  - 10.152.183.170
  externalTrafficPolicy: Cluster
  ipFamilies:
  - IPv4
  ipFamilyPolicy: SingleStack
  ports:
  - nodePort: 31223
    port: 8888
    protocol: TCP
    targetPort: 8888
  selector:
    app: httpenv
  sessionAffinity: None
  type: NodePort

 k get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
httpenv      NodePort    10.152.183.170   <none>        8888:31223/TCP   22m