feat(openapi): Remove go_package option requirement

cmd/protoc-gen-openapi/examples/tests/nogopackage/message.proto

@@ -0,0 +1,37 @@
+// Copyright 2021 Google LLC.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+syntax = "proto3";
+
+package tests.nogopackage.message.v1;
+
+import "google/api/annotations.proto";
+
+service Messaging {
+  rpc GetMessage(GetMessageRequest) returns(Message) {
+    option(google.api.http) = {
+        get: "/v1/messages/{message_id}"
+    };
+  }
+}
+
+message GetMessageRequest {
+  string message_id = 1;
+}
+
+message Message {
+  string message_id = 1;
+  string text = 2;
+}

cmd/protoc-gen-openapi/examples/tests/nogopackage/openapi.yaml

@@ -0,0 +1,84 @@
+# Generated with protoc-gen-openapi
+# https://github.com/fern-api/protoc-gen-openapi/tree/master/cmd/protoc-gen-openapi
+
+openapi: 3.0.3
+info:
+    title: Messaging API
+    version: 0.0.1
+paths:
+    /v1/messages/{message_id}:
+        get:
+            tags:
+                - Messaging
+            operationId: Messaging_GetMessage
+            parameters:
+                - name: message_id
+                  in: path
+                  required: true
+                  schema:
+                    type: string
+                    x-fern-encoding:
+                        proto:
+                            type: google.protobuf.StringValue
+            responses:
+                "200":
+                    description: OK
+                    content:
+                        application/json:
+                            schema:
+                                $ref: '#/components/schemas/Message'
+                default:
+                    description: Default error response
+                    content:
+                        application/json:
+                            schema:
+                                $ref: '#/components/schemas/GoogleRpcStatus'
+            x-fern-sdk-group-name: Messaging
+            x-fern-sdk-method-name: GetMessage
+            x-fern-request-name: GetMessageRequest
+components:
+    schemas:
+        GoogleProtobufAny:
+            type: object
+            properties:
+                '@type':
+                    type: string
+                    description: The type of the serialized message.
+            additionalProperties: true
+            description: Contains an arbitrary serialized message along with a @type that describes the type of the serialized message.
+            x-fern-encoding:
+                proto:
+                    type: google.protobuf.Any
+        GoogleRpcStatus:
+            type: object
+            properties:
+                code:
+                    type: integer
+                    description: The status code, which should be an enum value of [google.rpc.Code][google.rpc.Code].
+                    format: int32
+                message:
+                    type: string
+                    description: A developer-facing error message, which should be in English. Any user-facing error message should be localized and sent in the [google.rpc.Status.details][google.rpc.Status.details] field, or localized by the client.
+                details:
+                    type: array
+                    items:
+                        $ref: '#/components/schemas/GoogleProtobufAny'
+                    description: A list of messages that carry the error details.  There is a common set of message types for APIs to use.
+            description: 'The `Status` type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by [gRPC](https://github.com/grpc). Each `Status` message contains three pieces of data: error code, error message, and error details. You can find out more about this error model and how to work with it in the [API Design Guide](https://cloud.google.com/apis/design/errors).'
+        Message:
+            type: object
+            properties:
+                message_id:
+                    type: string
+                    x-fern-encoding:
+                        proto:
+                            type: google.protobuf.StringValue
+                text:
+                    type: string
+                    x-fern-encoding:
+                        proto:
+                            type: google.protobuf.StringValue
+            x-fern-type-name: Message
+            source: tests/nogopackage/message.proto
+tags:
+    - name: Messaging

cmd/protoc-gen-openapi/main.go

@@ -17,11 +17,16 @@ package main
 
 import (
 	"flag"
+	"fmt"
+	"io"
+	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/fern-api/protoc-gen-openapi/cmd/protoc-gen-openapi/generator"
 	"google.golang.org/protobuf/compiler/protogen"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/descriptorpb"
 	"google.golang.org/protobuf/types/pluginpb"
 )
 
@@ -46,25 +51,77 @@ func main() {
 		ParamFunc: flags.Set,
 	}
 
-	opts.Run(func(plugin *protogen.Plugin) error {
-		// Enable "optional" keyword in front of type (e.g. optional string label = 1;)
-		plugin.SupportedFeatures = uint64(pluginpb.CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL)
-		if *conf.OutputMode == "source_relative" {
-			for _, file := range plugin.Files {
-				if !file.Generate {
-					continue
-				}
-				outfileName := strings.TrimSuffix(file.Desc.Path(), filepath.Ext(file.Desc.Path())) + ".openapi.yaml"
-				outputFile := plugin.NewGeneratedFile(outfileName, "")
-				gen := generator.NewOpenAPIv3Generator(plugin, conf, []*protogen.File{file})
-				if err := gen.Run(outputFile); err != nil {
-					return err
-				}
+	if err := run(opts, conf); err != nil {
+		fmt.Fprintf(os.Stderr, "%s: %v\n", filepath.Base(os.Args[0]), err)
+		os.Exit(1)
+	}
+}
+
+func run(opts protogen.Options, conf generator.Configuration) error {
+	if len(os.Args) > 1 {
+		return fmt.Errorf("unknown argument %q (this program should be run by protoc, not directly)", os.Args[1])
+	}
+	in, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		return err
+	}
+	req := &pluginpb.CodeGeneratorRequest{}
+	if err := proto.Unmarshal(in, req); err != nil {
+		return err
+	}
+	// The protogen library requires every .proto file to have a go_package option,
+	// but this plugin generates OpenAPI specs — not Go code. Inject a synthetic
+	// go_package for any file that doesn't already have one so users aren't forced
+	// to add a Go-specific option to their proto files.
+	for _, fdesc := range req.ProtoFile {
+		if fdesc.GetOptions().GetGoPackage() == "" {
+			if fdesc.Options == nil {
+				fdesc.Options = &descriptorpb.FileOptions{}
+			}
+			pkg := fdesc.GetPackage()
+			if pkg == "" {
+				pkg = strings.TrimSuffix(filepath.Base(fdesc.GetName()), ".proto")
+			}
+			goPackage := "example.com/fake/" + strings.ReplaceAll(pkg, ".", "/")
+			fdesc.Options.GoPackage = &goPackage
+		}
+	}
+	gen, err := opts.New(req)
+	if err != nil {
+		return err
+	}
+	if err := generate(gen, conf); err != nil {
+		gen.Error(err)
+	}
+	resp := gen.Response()
+	out, err := proto.Marshal(resp)
+	if err != nil {
+		return err
+	}
+	if _, err := os.Stdout.Write(out); err != nil {
+		return err
+	}
+	return nil
+}
+
+func generate(plugin *protogen.Plugin, conf generator.Configuration) error {
+	// Enable "optional" keyword in front of type (e.g. optional string label = 1;)
+	plugin.SupportedFeatures = uint64(pluginpb.CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL)
+	if *conf.OutputMode == "source_relative" {
+		for _, file := range plugin.Files {
+			if !file.Generate {
+				continue
+			}
+			outfileName := strings.TrimSuffix(file.Desc.Path(), filepath.Ext(file.Desc.Path())) + ".openapi.yaml"
+			outputFile := plugin.NewGeneratedFile(outfileName, "")
+			gen := generator.NewOpenAPIv3Generator(plugin, conf, []*protogen.File{file})
+			if err := gen.Run(outputFile); err != nil {
+				return err
 			}
-		} else {
-			outputFile := plugin.NewGeneratedFile("openapi.yaml", "")
-			return generator.NewOpenAPIv3Generator(plugin, conf, plugin.Files).Run(outputFile)
 		}
-		return nil
-	})
+	} else {
+		outputFile := plugin.NewGeneratedFile("openapi.yaml", "")
+		return generator.NewOpenAPIv3Generator(plugin, conf, plugin.Files).Run(outputFile)
+	}
+	return nil
 }

cmd/protoc-gen-openapi/plugin_test.go

@@ -44,6 +44,7 @@ var openapiTests = []struct {
 	{name: "OpenAPIv3 Annotations", path: "examples/tests/openapiv3annotations/", protofile: "message.proto"},
 	{name: "AllOf Wrap Message", path: "examples/tests/allofwrap/", protofile: "message.proto"},
 	{name: "Additional Bindings", path: "examples/tests/additional_bindings/", protofile: "message.proto"},
+	{name: "No go_package option", path: "examples/tests/nogopackage/", protofile: "message.proto"},
 }
 
 // Set this to true to generate/overwrite the fixtures. Make sure you set it back