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Provide Load-Balanced Access to an Application in a Cluster | templates/tutorial |
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This page shows how to create a Kubernetes Service object that provides load-balanced access to an application running in a cluster.
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- Run two instances of a Hello World application
- Create a Service object
- Use the Service object to access the running application
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Creating a Service for an application running in two pods
-
Run a Hello World application in your cluster:
``` kubectl run hello-world --replicas=2 --labels="run=load-balancer-example" --image=gcr.io/google-samples/node-hello:1.0 --port=8080 ```
-
List the pods that are running the Hello World application:
``` kubectl get pods --selector="run=load-balancer-example" ```
The output is similar to this:
``` NAME READY STATUS RESTARTS AGE hello-world-2189936611-8fyp0 1/1 Running 0 6m hello-world-2189936611-9isq8 1/1 Running 0 6m ```
-
Create a Service object that exposes the deployment:
``` kubectl expose deployment <your-deployment-name> --type=NodePort --name=example-service ```
where
<your-deployment-name>
is the name of your deployment. -
Display the IP addresses for your service:
``` kubectl get services example-service ```
The output shows the internal IP address and the external IP address of your service. If the external IP address shows as
<pending>
, repeat the command.Note: If you are using Minikube, you don't get an external IP address. The external IP address remains in the pending state.
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE example-service 10.0.0.160 <pending> 8080/TCP 40s
-
Use your Service object to access the Hello World application:
curl <your-external-ip-address>:8080
where
<your-external-ip-address>
is the external IP address of your service.The output is a hello message from the application:
Hello Kubernetes!
Note: If you are using Minikube, enter these commands:
kubectl cluster-info kubectl describe services example-service
The output displays the IP address of your Minikube node and the NodePort value for your service. Then enter this command to access the Hello World application:
curl <minikube-node-ip-address>:<service-node-port>
where
<minikube-node-ip-address>
us the IP address of your Minikube node, and<service-node-port>
is the NodePort value for your service.
Using a service configuration file
As an alternative to using kubectl expose
, you can use a
service configuration file
to create a Service.
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Learn more about connecting applications with services. {{% /capture %}}