Learning how to handle errors sent out by a gRPC server in a REST Gateway and sending meaningful error responses to clients

The REST API Gateway is running on localhost:8082 and the gRPC server is running on localhost:8081.

1. Start the gRPC server

make start_grpc

2. Start the Gateway

make start_gateway

service CalculatorService {
    rpc DivideNumbers(DivideNumbersRequest) returns (DivideNumbersResponse);
}

// Divide number_one by number_two
message DivideNumbersRequest {
    float number_one = 1;
    float number_two = 2;
}

message DivideNumbersResponse {
    int32 code = 1;
    float answer = 2;
}

Endpoint: /calculator/divide

Method: POST

Request Body:

{
  "number_one": 10,
  "number_two": 0
}

Success Response:

{
  "code": 200,
  "answer": 0.01
}

Error Response:

// Errors out when number_two is 0 (Division by zero)
{
  "error": true,
  "message": "division by zero not possible"
}