This page shows how to create a Kubernetes Service object that exposes an external IP address.
Install kubectl.
Use a cloud provider like Google Kubernetes Engine or Amazon Web Services to create a Kubernetes cluster. This tutorial creates an external load balancer, which requires a cloud provider.
Configure kubectl
to communicate with your Kubernetes API server. For
instructions, see the documentation for your cloud provider.
Run a Hello World application in your cluster:
kubectl run hello-world --replicas=5 --labels="run=load-balancer-example" --image=gcr.io/google-samples/node-hello:1.0 --port=8080
The preceding command creates a Deployment object and an associated ReplicaSet object. The ReplicaSet has five Pods, each of which runs the Hello World application.
Display information about the Deployment:
kubectl get deployments hello-world
kubectl describe deployments hello-world
Display information about your ReplicaSet objects:
kubectl get replicasets
kubectl describe replicasets
Create a Service object that exposes the deployment:
kubectl expose deployment hello-world --type=LoadBalancer --name=my-service
Display information about the Service:
kubectl get services my-service
The output is similar to this:
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
my-service ClusterIP 10.3.245.137 104.198.205.71 8080/TCP 54s
Note: If the external IP address is shown as <pending>, wait for a minute and enter the same command again.
Display detailed information about the Service:
kubectl describe services my-service
The output is similar to this:
Name: my-service
Namespace: default
Labels: run=load-balancer-example
Annotations: <none>
Selector: run=load-balancer-example
Type: LoadBalancer
IP: 10.3.245.137
LoadBalancer Ingress: 104.198.205.71
Port: <unset> 8080/TCP
NodePort: <unset> 32377/TCP
Endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more...
Session Affinity: None
Events: <none>
Make a note of the external IP address (LoadBalancer Ingress
) exposed by
your service. In this example, the external IP address is 104.198.205.71.
Also note the value of Port
and NodePort
. In this example, the Port
is 8080 and the NodePort
is 32377.
In the preceding output, you can see that the service has several endpoints: 10.0.0.6:8080,10.0.1.6:8080,10.0.1.7:8080 + 2 more. These are internal addresses of the pods that are running the Hello World application. To verify these are pod addresses, enter this command:
kubectl get pods --output=wide
The output is similar to this:
NAME ... IP NODE
hello-world-2895499144-1jaz9 ... 10.0.1.6 gke-cluster-1-default-pool-e0b8d269-1afc
hello-world-2895499144-2e5uh ... 10.0.1.8 gke-cluster-1-default-pool-e0b8d269-1afc
hello-world-2895499144-9m4h1 ... 10.0.0.6 gke-cluster-1-default-pool-e0b8d269-5v7a
hello-world-2895499144-o4z13 ... 10.0.1.7 gke-cluster-1-default-pool-e0b8d269-1afc
hello-world-2895499144-segjf ... 10.0.2.5 gke-cluster-1-default-pool-e0b8d269-cpuc
Use the external IP address (LoadBalancer Ingress
) to access the Hello
World application:
curl http://<external-ip>:<port>
where <external-ip>
is the external IP address (LoadBalancer Ingress
)
of your Service, and <port>
is the value of Port
in your Service
description.
If you are using minikube, typing minikube service my-service
will
automatically open the Hello World application in a browser.
The response to a successful request is a hello message:
Hello Kubernetes!
To delete the Service, enter this command:
kubectl delete services my-service
To delete the Deployment, the ReplicaSet, and the Pods that are running the Hello World application, enter this command:
kubectl delete deployment hello-world
Learn more about connecting applications with services.
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