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Via CRs

This guide shows you how to create a GRPC API using Kubernetes Custom Resources.

Similar to the approach for REST APIs, this approach requires three CRs.

  • API CR
  • GRPCRoute CR
  • Backend CR

For this guide, you can create a sample backend for the GRPC API using the following command. 

kubectl apply -f https://raw.githubusercontent.com/wso2/apk/main/developer/tryout/samples/student-sample-backend.yaml -n <namespace>

The GRPC definition file used for this guide is available at this link.

Note

API CR

In the following CR, we have defined the GRPC API giving the name, context, and version information for the API. We have also referred to GRPCRoute resource in spec.production.routeRefs[0] path which we create in the next step.

---
kind: "API"
apiVersion: "dp.wso2.com/v1alpha3"
metadata:
  name: "student-service-api"
spec:
  apiName: "student-service-api"
  apiType: "GRPC"
  apiVersion: "v1"
  basePath: "/org.apk.v1"
  organization: "default"
  isDefaultVersion: false
  production:
  - routeRefs:
    - "student-service-api-route"

GRPCRoute CR

This is the resource where you define resources of your API. This GRPCRoute is linked to the API by referring to this resource name from the API resource. This GRPCRoute only points to some of the methods in the Student Service API.

apiVersion: "gateway.networking.k8s.io/v1alpha2"
kind: "GRPCRoute"
metadata:
  name: "student-service-api-route"
spec:
  hostnames:
  - "default.gw.wso2.com"
  rules:
  - matches:
    - method:
        type: "Exact"
        service: "student_service.StudentService"
        method: "GetStudent"
    backendRefs:
    - group: "dp.wso2.com"
      kind: "Backend"
      name: "student-service-backend"
  - matches:
    - method:
        type: "Exact"
        service: "student_service.StudentService"
        method: "SendStudentStream"
    backendRefs:
    - group: "dp.wso2.com"
      kind: "Backend"
      name: "student-service-backend"
  parentRefs:
  - group: "gateway.networking.k8s.io"
    kind: "Gateway"
    name: "wso2-apk-default"
    sectionName: "httpslistener"

Backend CR

In the above created GQLRoute resource we have referred to a Backend resource in spec.rules[0].backendRefs[0] path. That Backend should be created as below:

apiVersion: "dp.wso2.com/v1alpha2"
kind: "Backend"
metadata:
  name: "student-service-backend"
spec:
  services:
  - host: "student-backend"
    port: 6565
  basePath: ""
  protocol: "http"

This Backend CR points to the backend that can be created using the following command. Replace with the relevant name of the namespace.

kubectl apply -f https://raw.githubusercontent.com/wso2/apk/main/developer/tryout/samples/student-sample-backend.yaml -n <namespace>

The host, port, basepath fields should point to your GRPC backend. If your backend is a Kubernetes-native Service, then derive the following value according to your Service and use it as the host. 

<spec.metadata.name>.<spec.metadata.namespace>

Once you have designed your APIs using these essential CRs, the next step is to apply them to the Kubernetes API server. APK will process and deploy your APIs seamlessly, taking full advantage of the Kubernetes infrastructure.

kubectl apply -f <path_to_CR_files> -n <namespace>