proto + grpc + swagger makefile (golang)

Makefile

PKG_PATH := pkg

PROTOC := protoc
PROTOS := $(sort $(shell find ./$(PKG_PATH) -type f -name '*.proto' -print))
GO_PROTO_SOURCES := $(PROTOS:%.proto=%.pb.go)
GW_PROTO_SOURCES := $(PROTOS:%.proto=%.pb.gw.go)
SWAGGER_SOURCES := $(PROTOS:%.proto=%.swagger.json)

PROTO_IMPORT_PATH := \
	-I $(PKG_PATH) \
	-I vendor/github.com/grpc-ecosystem/grpc-gateway/ \
	-I vendor/github.com/gogo/googleapis/ \
	-I vendor/

PROTO_MAPPINGS := \
	Mgoogle/protobuf/timestamp.proto=github.com/gogo/protobuf/types, \
	Mgoogle/protobuf/duration.proto=github.com/gogo/protobuf/types, \
	Mgoogle/protobuf/empty.proto=github.com/gogo/protobuf/types, \
	Mgoogle/api/annotations.proto=github.com/gogo/googleapis/google/api, \
	Mgoogle/protobuf/field_mask.proto=github.com/gogo/protobuf/types

space :=
space +=
PROTO_MAPPINGS := $(subst $(space),,$(PROTO_MAPPINGS))

OPENAPI_PATH := third_party/openapi

%.pb.go: %.proto
		$(PROTOC) $(PROTO_IMPORT_PATH) \
			--gogo_out=plugins=grpc,paths=source_relative,$(PROTO_MAPPINGS):./$(PKG_PATH) \
			$<

%.pb.gw.go: %.proto
		$(PROTOC) $(PROTO_IMPORT_PATH) \
			--grpc-gateway_out=allow_patch_feature=false,paths=source_relative,$(PROTO_MAPPINGS):./$(PKG_PATH) \
			$<

%.swagger.json: %.proto $(OPENAPI_PATH)
		$(PROTOC) $(PROTO_IMPORT_PATH) \
			--swagger_out=$(OPENAPI_PATH) \
			$<

$(OPENAPI_PATH):
		@mkdir -p $@

.PHONY: swagger
swagger: $(SWAGGER_SOURCES)

.PHONY: proto
proto: $(GO_PROTO_SOURCES) $(GW_PROTO_SOURCES)