Java-based extension with API exposed via Microgateway

Overview

This sample demonstrates how to build and deploy a Java-based microservice as an extension and expose the API in SAP BTP, Kyma runtime.

This sample demonstrates how to:

• Create a development Namespace in the Kyma runtime.
• Create and deploy a Spring Boot application in the Kyma runtime.
• Expose the Spring Boot application using APIRules.
• Explore the APIs.

Prerequisites

• SAP BTP, Kyma runtime instance
• Kubernetes tooling
• Docker
• make
• Gradle
• Pack if building images using buildpacks

Application

The Spring Boot application implements a simple Orders API with CRUD operations.

Steps

Prepare for deployment

• Create a new dev Namespace:

  kubectl create namespace dev
  kubectl label namespaces dev istio-injection=enabled
  

• Build the image

  • Using Dockerfile

    DOCKER_ACCOUNT={your-docker-account} make build-image-using-docker
    

  • or, alternatively Using Buildpacks

    DOCKER_ACCOUNT={your-docker-account} make build-image-using-pack
    

• Push the image

  DOCKER_ACCOUNT={your-docker-account} make push-image
  

Kubernetes Deployment

This section details out deploying the extension using standard Kubernetes resources.

To deploy as Helm chart, please refer to Helm Chart Deployment

• Update the image name in the Kubernetes Deployment. Refer to the standard Kubernetes Deployment and Service definitions.

• Deploy the application:

  kubectl -n dev apply -f ./k8s/deployment.yaml
  

• Verify that the Pods are up and running:

  kubectl -n dev get po
  

The expected result shows that the Pod for the sample-extension-java Deployment is running:

Expose the API

• Create an APIRule. In the APIRule, specify the Kubernetes Service that is exposed:

apiVersion: gateway.kyma-project.io/v2
kind: APIRule
metadata:
  name: sample-extension-java
spec:
  gateway: kyma-system/kyma-gateway
  hosts: 
  - sample-extension-java
  rules:
    - noAuth: true
      methods:
        - GET
        - POST
        - PUT
        - DELETE
      path: /*
      service:
        name: sample-extension-java
        port: 8080

This sample snippet exposes the sample-extension-java Service. The Service is specified in the spec.service.name field. The sample-extension-java subdomain is specified in the spec.service.host field.

• Apply the APIRule:

  kubectl -n dev apply -f ./k8s/api-rule.yaml
  

Helm Chart Deployment

A Helm Chart definition is also available for developers to try out.

Must Haves

• kubectl
• Helm3

Helm install

To install the helm chart in dev namespace, run the following command. Change to use your image. You can also override other parameters defined in values.yaml

helm -n dev install kymaapp ../helm-charts/sample-extension-java --set image.repository=gabbi/sample-extension-java:0.0.7 --set jdbc.user={db user} --set jdbc.password={db password}

To verify, the installed chart, run:

helm -n dev ls

Try it out

Access the APIs through this URL: <https://sample-extension-java.{cluster domain}/orders>

Try out various APIs.