move-away-from-grpc-gateway

name	move-away-from-grpc-gateway
description	Moves a mockgcp service from using locally generated grpc-gateway proto bindings to using reflection with the official Google Cloud Go client library (httptogrpc). Use this when tasked with stopping grpc-gateway generation for a GCP service in mockgcp.

Move away from grpc-gateway

This skill outlines the steps to transition a mockgcp service from using grpc-gateway to using reflection via httptogrpc.

Step 1: Stop generating protos

In mockgcp/Makefile, remove the service from the gen-proto-no-fixup target. Find the line that looks like ./third_party/googleapis/mockgcp/cloud/<service_name>/v1/*.proto \ and delete it.

Step 2: Delete generated files

Delete the generated code for the service located in: mockgcp/generated/mockgcp/cloud/<service_name>/ Run rm -rf mockgcp/generated/mockgcp/cloud/<service_name> to remove the .pb.go, .pb.gw.go, and _grpc.pb.go files for all versions.

Step 3: Update imports

Update the Go files in mockgcp/mock<service_name>/ (typically service.go, instance.go, etc.):

• Remove the local generated import: pb "github.com/GoogleCloudPlatform/k8s-config-connector/mockgcp/generated/mockgcp/cloud/<service_name>/<version>"
• Add the official client library import: pb "cloud.google.com/go/<service_name>/apiv1/<service_name>pb"

Step 4: Switch HTTP Multiplexer to httptogrpc

In mockgcp/mock<service_name>/service.go, update the NewHTTPMux method.

• Replace "github.com/GoogleCloudPlatform/k8s-config-connector/mockgcp/common/httpmux" with "github.com/GoogleCloudPlatform/k8s-config-connector/mockgcp/common/httptogrpc"
• Remove the httpmux.NewServeMux call and replace it with httptogrpc.NewGRPCMux(conn).

Example:

func (s *MockService) NewHTTPMux(ctx context.Context, conn *grpc.ClientConn) (http.Handler, error) {
	grpcMux, err := httptogrpc.NewGRPCMux(conn)
	if err != nil {
		return nil, fmt.Errorf("error building grpc service: %w", err)
	}

	grpcMux.AddService(pb.NewMemorystoreClient(conn)) // Replace MemorystoreClient with the correct client
	grpcMux.AddOperationsPath("/v1/{prefix=**}/operations/{name}", conn)

	return grpcMux, nil
}

Step 5: Fix type mismatches

The official client library proto types might differ slightly from the old grpc-gateway types:

• You may need to replace pointer field assignments with new(bool) or specific constant types.
• Check and fix compilation errors by running go build or go test in the service directory.
• Update uuid generation or default field behaviors to match the strict types in the official client.