gRPC-Gateway REST API Example

This project demonstrates the use of gRPC-Gateway to serve both gRPC and REST clients from a single application, adhering to the Google APIs standards for interface definitions. It leverages the gRPC-Gateway plugin to generate a reverse-proxy server that translates a RESTful HTTP API into gRPC. This allows the API to be accessible via both gRPC methods and traditional HTTP REST calls.

Features

• gRPC server implementation in Go.
• RESTful API gateway to the gRPC server following Google APIs standards.
• Example service definition with gRPC-Gateway annotations.
• Makefile for easy project setup and operations.

Prerequisites

• Go 1.15 or later.
• Protocol Buffer Compiler (protoc) installed on your system.
• GOPATH environment variable set.

Installation

Clone the Repository

First, clone this repository to your local machine:

git clone https://github.com/squaick/grpc-gateway-rest-api-example
cd grpc-gateway-rest-api-example

Install Dependencies

Run the following command to install the necessary dependencies, including the Protocol Buffer compiler plugins for Go, gRPC, and gRPC-Gateway:

make install-deps

Clone Additional Protobuf Sources

Some protobuf definitions require Google's API common protos. Clone these into your GOPATH as follows:

make clone-googleapis

Running go mod tidy

Ensure your project's dependencies are clean and up to date by running:

go mod tidy

This command will download the necessary Go modules and remove any unused dependencies.

Generating protobuffs

To generate the Go bindings for your .proto files and the reverse-proxy server, run:

make generate

This command compiles the protobuf definitions and generates the necessary Go files in the generated_pb directory.

Running the Project

Start the gRPC and REST Servers

To start both the gRPC server and the REST gateway, simply run:

go run server.go

This command starts the gRPC server listening on port 3000 and the REST gateway on port 3001.

Testing the API

You can test the gRPC service using a gRPC client and the REST API using any HTTP client (e.g., curl, Postman).

gRPC Example

Use a gRPC client to call the service:

// Example gRPC client call (pseudo-code)
client := NewSayHelloServiceClient(conn)
response, err := client.SayHello(context.Background(), &HelloRequest{Name: "World"})

or with grpcurl:

grpcurl -plaintext -d '{"name": "World"}' localhost:3000 grpcGateway.sayHelloService/sayHello

REST Example

To test the REST API, you can use curl:

curl http://localhost:3001/v1/hello/World

This should return a JSON response from the REST gateway, which in turn communicates with the gRPC server:

{
  "message": "Hello World"
}