/spring-operator-demo

Primary LanguageJava

Spring K8s Operator example

Example of a K8s operator using Spring Boot v3 and the Official Kubernetes Java client.

Structure

  • 2 projects with https://start.spring.io.

    • default-spring-boot-app: normal web app used as example of Spring Boot app (with actuator, web)

    • spring-deployment-operator: the actual focus of this repo, the K8s native operator.

  • 1 scripts directory with utilities.

  • 1 manifests directory for Kubernetes configuration.

Build & deploy

Generating Model classes from CRD

The example crd found in spring-operator-demo/manifests/crds/spring-deployment-crd.yaml defines a new K8s resource to manage Spring Boot deployments. To generate the Model classes to be used in our operator run ./scripts/generate_model.sh.

Running in local k8s cluster

Create KinD cluster.

kind create cluster --config kind-config.yaml

Run build and deploy script

./scripts/build_and_deploy.sh

Direct execution

Cannot be run as app until permissions are correctly set. Locally api calls work, but not the controller in k8s

So long you have .kube/config, the kubernetes client will connect.

kind create cluster --config kind-config.yaml

Start OperatorApplication from IntelliJ

./spring-deployment-operator/gradlew -p spring-deployment-operator bootBuildImage
kind load docker-image spring-deployment-operator:0.0.1-SNAPSHOT

Running the example

After running build_and_deploy.sh you should see the operator pod running in spring-deploy-operator with:

kubectl get pods -n spring-deploy-operator

Apply the example provided.

kubectl apply -f manifests/examples/spring-deployment.yaml

Then, list the pods again to see the new deployment and 2 pods associated with it.

> kubectl get deploy -n spring-deploy-operator

NAME                         READY   UP-TO-DATE   AVAILABLE   AGE
hello-madrid                 2/2     2            2           3m3s
spring-deployment-operator   1/1     1            1           43m
> kubectl get pods -n spring-deploy-operator

NAME                                          READY   STATUS    RESTARTS   AGE
hello-madrid-6d4f4dc5c6-fwd7l                 1/1     Running   0          2m16s
hello-madrid-6d4f4dc5c6-v4sck                 1/1     Running   0          2m16s
spring-deployment-operator-6b6cb9655b-m8zjl   1/1     Running   0          42m

As a bonus, since we installed metrics server, we can monitor the resources to see the difference between the normal deployments and a native one.

Note
 Numbers may vary. 
> kubectl top pods

NAME                                          CPU(cores)   MEMORY(bytes)
hello-madrid-6d4f4dc5c6-fwd7l                 9m           158Mi
hello-madrid-6d4f4dc5c6-v4sck                 6m           155Mi
spring-deployment-operator-6b6cb9655b-m8zjl   1m           44Mi

Learnt lessons

  • Remove timestamp from generated Java code if you commit

References