Handle google protobuf well known types

[rocketraman]

The protobuf "well-known types" (https://developers.google.com/protocol-buffers/docs/reference/google.protobuf) are included in every language runtime, including the npm package (see protocolbuffers/protobuf#1638).

Currently, grpcc requires proto files that import a well-known type to have a copy of the well-known type locally, otherwise you get an Error: failed to import '...' in './foo.proto': file not found error.

These well-known types should be handled automatically by importing them from the protobuf npm package instead.

[drigz]

I've looked in to this a bit. grpcc uses grpc-node which in turn uses protobuf.js to load proto files. protobuf.js seems not to plan to have special support for the well known types (protobufjs/protobuf.js#447). protobuf.js v6 adds support for changing how paths are resolved (protobufjs/protobuf.js#368 (comment)) which would allow grpcc to add logic to import from multiple paths, but grpc-node rolled back their change to use v6 (grpc/grpc-node#103). So it seems this can't easily be done.

I've worked around it with a symlink in the root of my repo:

ln -s $HOME/git/google/protobuf/src/google google
echo "/google" >> ~/.gitignore

[jeffzoch]

Just wanted to point grpc/grpc-node#103 has been closed with the addition of @grpc/proto-loader and thus this issue can be fixed I believe.

[valentindotxyz]

Hhm, I still have this issue as of today :(

[lzuwei]

facing the same issue as well

Error: failed to import 'path/to/my/service/pb/google/protobuf/empty.proto' 

[claudiocabral]

I started working on a fix, using @grpc/proto-loader but the backwards compatibility is not great. I got it to work, but we lose all information about the message types and I'm not quite sure it actually works (so far my test messages come back empty)

[jfyne]

@claudiocabral I built on your start and finished it off with #61

[jfyne]

I have also created a docker image with built in common protobuf includes here which includes the @grpc/proto-loader code. I use it with google/protobuf/timestamp.proto successfully.

https://hub.docker.com/r/jfyne/grpcc/