k8s-grpc-gateway-example

This is a sample gRPC Server with HTTP gateway using grpc-gateway library.

It implements following proto file:

syntax = "proto3";
option go_package = "proto;proto";

package proto;

import "google/api/annotations.proto";

message RequestMessage {
	string message = 1;
}

message ResponseMessage {
	string host = 1;
	string message = 2;
}

service EchoService {
	rpc Echo(RequestMessage) returns (ResponseMessage) {
		option (google.api.http) = {
			get: "/v1/echo/{message}"
			additional_bindings {
				get: "/v1/echo"
			}
		};
	}
}

How to run?

Run the image on docker using following command:

docker run -p 8080:8080 -p 9090:9090 vivekmarakana/k8s-grpc-gateway:latest

Make gRPC Calls

gRPC server is run on port 9090 with reflections enabled so you won't need to provide the proto files to client like evans. You can directly call the service by running:

bash-3.2$ evans repl --host localhost --port 9090 --reflection

  ______
 |  ____|
 | |__    __   __   __ _   _ __    ___
 |  __|   \ \ / /  / _. | | '_ \  / __|
 | |____   \ V /  | (_| | | | | | \__ \
 |______|   \_/    \__,_| |_| |_| |___/

 more expressive universal gRPC client


[email protected]:9090> call Echo
message (TYPE_STRING) => hello
{
  "host": "127.0.0.1",
  "message": "hello"
}

Make REST Calls

HTTP gateway is running on port 8080. You can call it using browser or curl:

bash-3.2$ curl -s localhost:8080/v1/echo | jq
{
  "host": "127.0.0.1",
  "message": ":("
}
bash-3.2$ curl -s localhost:8080/v1/echo/hello | jq
{
  "host": "127.0.0.1",
  "message": "hello"
}

Deployment on Kubernetes

The repo contains the kubernetes kustomization files in k8s directory. If you have kubernetes cluster setup already, you can deploy this using the following command:

kubectl apply -k ./k8s 

This will run the deployment with 1 replica and a NodePort service. To get the port to connect to use the command:

bash-3.2$ kubectl get service grpc-gateway-service
NAME                   TYPE       CLUSTER-IP       EXTERNAL-IP   PORT(S)                         AGE
grpc-gateway-service   NodePort   10.107.229.130   <none>        9090:32013/TCP,8080:31520/TCP   17s

Now you can make grpc calls on port 32013(container port 9090) and http calls on 31520(container port 8080).

How to make changes & build locally?

• If you want to change the proto/echo_service.proto, you can run make gp after changing the file.
• To run locally, use the command go run src/main.go
• To build a binary, run the command make build. This will create a binary bin/server
• To build docker image you can run DOCKER_HUB_USERNAME=<YOUR_USERNAME> make dockerbuild. This will make the local image and tag it with <YOUR_USERNAME>/k8s-grpc-gateway:latest which you can publish with docker push