grpc-ecosystem/grpc-gateway

protoc-gen-openapiv2: `go_package` option is required since version 2.0.1

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#2,127 opened on May 6, 2021

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bughelp wanted

Description

🐛 Bug Report

Since version 2.0.1, the protobuf option go_package is required to generate the gateway or the OpenAPI schema.

To Reproduce

Using this .proto file:

syntax = "proto3";
package your.service.v1;

message StringMessage {
  string value = 1;
}

service YourService {
  rpc Echo(StringMessage) returns (StringMessage) {}
}

Running protoc like so:

protoc -I . --grpc-gateway_out ./output my_service.proto

The output is:

protoc-gen-grpc-gateway: unable to determine Go import path for "my_service.proto"

Please specify either:
	• a "go_package" option in the .proto source file, or
	• a "M" argument on the command line.

See https://developers.google.com/protocol-buffers/docs/reference/go-generated#package for more information.

(The problem is the same with protoc-gen-openapiv2)

Expected behavior

The go_package option shouldn't be require, at least to produce the OpenAPI output since this value has no meaning for this generator.

Ideally, it wouldn't be required for generating the gateway as well since the gateway is meant to be a runnable binary and not linked against as code.

Actual Behavior

protoc-gen-grpc-gateway: unable to determine Go import path for "my_service.proto"

Please specify either:
	• a "go_package" option in the .proto source file, or
	• a "M" argument on the command line.

See https://developers.google.com/protocol-buffers/docs/reference/go-generated#package for more information.

Your Environment

MacOS Catalina, gen-gateway and openapiv2 from 2.0.1 to 2.4.0 all exhibit the same behaviour

protoc --version
libprotoc 3.14.0

Contributor guide

Tech stack
go
Domain
backendapitooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go programmingProtocol Buffersgrpc gateway codebase
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Start by examining the protoc gen openapiv2 plugin code, specifically the logic that checks for the go package option. Look for where the error message 'unable to determine Go import path' is generated. The goal is to allow generating OpenAPI output even when go package is not set, as it is not needed for OpenAPI. Review the comments in issue #2127 for any proposed solutions or design discussions. Consider adding a flag or environment variable to skip the go package requirement for OpenAPI generation.