grpc-gateway: Run http server and grpc server in same pod

Pre: Install tool https://github.com/bufbuild/buf

I. How to run this example

$ buf generate ## generate service

$ go mod tidy && go mod vendor

$ go build -o server cmd/server/main.go && ./server

you will see server listening in two port
http at 9000 and grpc at 10000
after that you can test http server with postman or curl 
curl example
$ curl -d '{"name":"you name", "age": 18}' -X POST 'http://localhost:9000/api/v1/users'


Test grpc server with example client
$ go build -o client cmd/client/client.go && ./client

expected client log
[hongminh] result after create user, resp = {"code":1,"messsage":"success","data":{"user_id":1632568428}}, error = <nil>    
[minh] result after create user, resp = null, error = rpc error: code = Unknown desc = name existed

II. headers support: case "Accept", "Accept-Charset", "Accept-Language", "Accept-Ranges", "Authorization", "Cache-Control", "Content-Type", "Cookie", "Date", "Expect", "From", "Host", "If-Match", "If-Modified-Since", "If-None-Match", "If-Schedule-Tag-Match", "If-Unmodified-Since", "Max-Forwards", "Origin", "Pragma", "Referer", "User-Agent", "Via", "Warning":

III. Notes

	s := grpc.NewServer(
		grpc.UnaryInterceptor(
			grpc_middleware.ChainUnaryServer(customMiddleware),
		),
	)
// grpc middleware only for grpc, not for http request