go-grpc-gateway-server

This repository provides an example for go based microservice. Go micro services developed based on gRPC protobuf's and also uses gRPC gateway as a reverse proxy to support JSON clients/requests.

Dev pre-requisites

1. golang

   brew install go
   Note: Make sure to have go1.17.2 or latest
   

2. Docker

   brew install docker
   

   or downlooad docker from here

3. PgAdmin for Postgres DB, download and this is optional if you prefer cli

4. Update env

   vi ~/.zshrc
   
   add below entries, save & exit.
   
   export GOPATH=$HOME/go
   export PATH=$PATH:$GOPATH/bin
   export GONOPROXY="github.com,gopkg.in,go.uber.org"
   

   source ~/.zshrc
   

Install protoc

If you have Homebrew (which you can get from https://brew.sh), just run:

brew install protobuf

If you see any error messages, run brew doctor, follow any recommended fixes, and try again. If it still fails, try instead:

brew upgrade protobuf

Alternately, run the following commands:

PROTOC_ZIP=protoc-3.14.0-osx-x86_64.zip
curl -OL https://github.com/protocolbuffers/protobuf/releases/download/v3.14.0/$PROTOC_ZIP
sudo unzip -o $PROTOC_ZIP -d /usr/local bin/protoc
sudo unzip -o $PROTOC_ZIP -d /usr/local 'include/*'
rm -f $PROTOC_ZIP```

go install \
github.com/grpc-ecosystem/grpc-gateway/v2/protoc-gen-grpc-gateway@latest \
github.com/grpc-ecosystem/grpc-gateway/v2/protoc-gen-openapiv2@latest \
google.golang.org/protobuf/cmd/protoc-gen-go@latest \
google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest

Note: Make sure protobuf's installed correctly by running protoc --version

Generate protobuf's

Note: Required this step only when you make changes to .proto file or introduce a new one

cd pkg/api

go generate ./...

(or) alternative try below in case you did not set GOPATH

env PATH="$HOME/go/bin:$PATH" go generate ./...

Following 3 files are auto generated ones with above command

api/test_api.pb.go
api/test_api.pb.gw.go
api/test_api_grpc.pb.go

Build and Run Docker

docker compose build

docker compose up

Instructions for Developers

How to add a new service & test?

This section demonstrates, how to add a new grpc gateway service, implement and test it in local.

Note: Follow naming standards from here: https://cloud.google.com/apis/design/naming_convention#method_names

####1. Add new proto changes Lets add a test api called SayHello to pkg/api/test_api.proto

// SayHello service generates a greeting message
rpc SayHello(SayHelloRequest) returns (SayHelloResponse) {
 option (google.api.http) = {
   post: "/v1/greet"
   body: "*"
 };
}

Add request SayHelloRequest & response SayHelloResponse objects declared above

// Request Message for greeting service
message SayHelloRequest {
string name = 1;
}

// Response Message for greeting service
message SayHelloResponse {
string msg = 1;
}

####2. generate protobufs

cd pkg/api

go generate ./...

(or) alternative try below in case you did not set GOPATH

env PATH="$HOME/go/bin:$PATH"

####3. Implement service handler

func (s *Server) SayHello(ctx context.Context, request *api.SayHelloRequest) (*api.SayHelloResponse, error) {

	s.Log.Info("Hit to SayHello service and Request=%s", request.Name)
	response := &api.SayHelloResponse{Msg: "Hello " + request.Name + "!!"}
	return response, nil
}

####4. Build, Deploy and Test

docker compose build

docker compose up

curl -X POST -d '{"name": "John Doe" }' -H 'Content-Type: application/json' 
http://localhost:9091/v1/greet

Response:

{"msg": "Hello John Doe!!"}