Test your Java deployment
Prerequisites
- Complete all the previous sections of this guide, starting with Containerize your app.
- Turn on Kubernetes in Docker Desktop.
Overview
In this section, you'll learn how to use Docker Desktop to deploy your application to a fully-featured Kubernetes environment on your development machine. This lets you test and debug your workloads on Kubernetes locally before deploying.
Create a Kubernetes YAML file
In your spring-petclinic
directory, create a file named
docker-java-kubernetes.yaml
. Open the file in an IDE or text editor and add
the following contents. Replace DOCKER_USERNAME/REPO_NAME
with your Docker
username and the name of the repository that you created in
Configure CI/CD for
your Java application.
apiVersion: apps/v1
kind: Deployment
metadata:
name: docker-java-demo
namespace: default
spec:
replicas: 1
selector:
matchLabels:
service: server
template:
metadata:
labels:
service: server
spec:
containers:
- name: server-service
image: DOCKER_USERNAME/REPO_NAME
imagePullPolicy: Always
---
apiVersion: v1
kind: Service
metadata:
name: service-entrypoint
namespace: default
spec:
type: NodePort
selector:
service: server
ports:
- port: 8080
targetPort: 8080
nodePort: 30001
In this Kubernetes YAML file, there are two objects, separated by the ---
:
- A Deployment, describing a scalable group of identical pods. In this case,
you'll get just one replica, or copy of your pod. That pod, which is
described under
template
, has just one container in it. The container is created from the image built by GitHub Actions in Configure CI/CD for your Java application. - A NodePort service, which will route traffic from port 30001 on your host to port 8080 inside the pods it routes to, allowing you to reach your app from the network.
To learn more about Kubernetes objects, see the Kubernetes documentation.
Deploy and check your application
In a terminal, navigate to
spring-petclinic
and deploy your application to Kubernetes.$ kubectl apply -f docker-java-kubernetes.yaml
You should see output that looks like the following, indicating your Kubernetes objects were created successfully.
deployment.apps/docker-java-demo created service/service-entrypoint created
Make sure everything worked by listing your deployments.
$ kubectl get deployments
Your deployment should be listed as follows:
NAME READY UP-TO-DATE AVAILABLE AGE docker-java-demo 1/1 1 1 15s
This indicates all one of the pods you asked for in your YAML are up and running. Do the same check for your services.
$ kubectl get services
You should get output like the following.
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 23h service-entrypoint NodePort 10.99.128.230 <none> 8080:30001/TCP 75s
In addition to the default
kubernetes
service, you can see yourservice-entrypoint
service, accepting traffic on port 30001/TCP.In a terminal, curl the service. Note that a database wasn't deployed in this example.
$ curl --request GET \ --url http://localhost:30001/actuator/health \ --header 'content-type: application/json'
You should get output like the following.
{"status":"UP","groups":["liveness","readiness"]}
Run the following command to tear down your application.
$ kubectl delete -f docker-java-kubernetes.yaml
Summary
In this section, you learned how to use Docker Desktop to deploy your application to a fully-featured Kubernetes environment on your development machine.
Related information: