Kubernetes 102: Exposing an External IP Address to Access an Application in a Cluster

Get kubernetes nodes:

k3os-3249 [~]$ kubectl get nodes
NAME         STATUS   ROLES    AGE   VERSION
k3os-22710   Ready    <none>   10m   v1.14.1-k3s.4
k3os-3249    Ready    <none>   17h   v1.14.1-k3s.4

Get cluster info:

k3os-3249 [~]$ kubectl cluster-info
Kubernetes master is running at https://localhost:6443
CoreDNS is running at https://localhost:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

Creating a service for an application running in two pods:

k3os-3249 [ ~ ]$ kubectl run --generator=run-pod/v1  hello-world --replicas=2 --labels="run=load-balancer-example" --image=gcr.io/google-samples/node-hello:1.0  --port=8080
deployment.apps/hello-world created

Display information about the Deployment:

k3os-3249 [/kubernetes]$ kubectl get all
NAME                              READY   STATUS              RESTARTS   AGE
pod/hello-world-68ff65cf7-bxg6j   0/1     ContainerCreating   0          29s
pod/hello-world-68ff65cf7-ptz9p   0/1     ContainerCreating   0          29s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.43.0.1    <none>        443/TCP   17h

NAME                          READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/hello-world   0/2     2            0           29s

NAME                                    DESIRED   CURRENT   READY   AGE
replicaset.apps/hello-world-68ff65cf7   2         2         0       29s

k3os-3249 [/kubernetes]$ kubectl get all
NAME                              READY   STATUS    RESTARTS   AGE
pod/hello-world-68ff65cf7-bxg6j   1/1     Running   0          20m
pod/hello-world-68ff65cf7-ptz9p   1/1     Running   0          20m

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.43.0.1    <none>        443/TCP   18h

NAME                          READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/hello-world   2/2     2            2           20m

NAME                                    DESIRED   CURRENT   READY   AGE
replicaset.apps/hello-world-68ff65cf7   2         2         2       20m

Display information about the Deployment:

k3os-3249 [/kubernetes]$ kubectl get deployments hello-world
NAME          READY   UP-TO-DATE   AVAILABLE   AGE
hello-world   2/2     2            2           21m

k3os-3249 [/kubernetes]$ kubectl describe deployments hello-world
Name:                   hello-world
Namespace:              default
CreationTimestamp:      Mon, 10 Jun 2019 08:57:12 +0000
Labels:                 run=load-balancer-example
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               run=load-balancer-example
Replicas:               2 desired | 2 updated | 2 total | 2 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  run=load-balancer-example
  Containers:
   hello-world:
    Image:        gcr.io/google-samples/node-hello:1.0
    Port:         8080/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   hello-world-68ff65cf7 (2/2 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  21m   deployment-controller  Scaled up replica set hello-world-68ff65cf7 to 2

Display information about your ReplicaSet objects:

k3os-3249 [/kubernetes]$ kubectl get replicasets
NAME                    DESIRED   CURRENT   READY   AGE
hello-world-68ff65cf7   2         2         2       23m

k3os-3249 [~]$ kubectl describe replicasets
Name:           hello-world-68ff65cf7
Namespace:      default
Selector:       pod-template-hash=68ff65cf7,run=load-balancer-example
Labels:         pod-template-hash=68ff65cf7
                run=load-balancer-example
Annotations:    deployment.kubernetes.io/desired-replicas: 2
                deployment.kubernetes.io/max-replicas: 3
                deployment.kubernetes.io/revision: 1
Controlled By:  Deployment/hello-world
Replicas:       2 current / 2 desired
Pods Status:    2 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  pod-template-hash=68ff65cf7
           run=load-balancer-example
  Containers:
   hello-world:
    Image:        gcr.io/google-samples/node-hello:1.0
    Port:         8080/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Events:
  Type    Reason            Age   From                   Message
  ----    ------            ----  ----                   -------
  Normal  SuccessfulCreate  23m   replicaset-controller  Created pod: hello-world-68ff65cf7-ptz9p
  Normal  SuccessfulCreate  23m   replicaset-controller  Created pod: hello-world-68ff65cf7-bxg6j

 Create a Service object that exposes the deployment:

k3os-3249 [~]$ kubectl expose deployment hello-world --type=LoadBalancer --name=my-service
service/my-service exposed

Display information about the Service:

k3os-3249 [~]$ kubectl get services my-service
NAME         TYPE           CLUSTER-IP      EXTERNAL-IP                     PORT(S)          AGE
my-service   LoadBalancer   10.43.231.148   192.168.17.178,192.168.17.179   8080:30518/TCP   77s

Display detailed information about the Service:

k3os-3249 [~]$ kubectl describe services my-service
Name:                     my-service
Namespace:                default
Labels:                   run=load-balancer-example
Annotations:              <none>
Selector:                 run=load-balancer-example
Type:                     LoadBalancer
IP:                       10.43.231.148
LoadBalancer Ingress:     192.168.17.178, 192.168.17.179
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  30518/TCP
Endpoints:                10.42.0.10:8080,10.42.1.6:8080
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>

Display information about the Pods:

k3os-3249 [~]$ kubectl get pods --output=wide
NAME                          READY   STATUS    RESTARTS   AGE    IP           NODE         NOMINATED NODE   READINESS GATES
hello-world-68ff65cf7-bxg6j   1/1     Running   0          28m    10.42.0.10   k3os-3249    <none>           <none>
hello-world-68ff65cf7-ptz9p   1/1     Running   0          28m    10.42.1.6    k3os-22710   <none>           <none>
svclb-my-service-flw2l        1/1     Running   0          3m9s   10.42.1.7    k3os-22710   <none>           <none>
svclb-my-service-hlqpq        1/1     Running   0          3m9s   10.42.0.11   k3os-3249    <none>           <none>

Use the external IP address (LoadBalancer Ingress) to access the Hello World application:

k3os-3249 [~]$ curl http://192.168.17.179:8080

Use the Cluster IP address to access the Hello World application inside machines:

k3os-3249 [~]$ curl http://10.43.231.148:8080
Hello Kubernetes!

Cleaning up

To delete the Service:

k3os-3249 [~]$ kubectl delete services my-service

To delete the Deployment, the ReplicaSet, and the Pods that are running the Hello World application:

k3os-3249 [~]$ kubectl delete deployment hello-world

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