Add gRPC metadata example

[kamilmysliwiec]

I'm submitting a...

[ ] Regression 
[ ] Bug report
[ ] Feature request
[ ] Documentation issue or request (new chapter/page)
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

Expected behavior

As a user, I would like to see passing gRPC metadata example

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Environment

For Tooling issues:
- Node version: XX  
- Platform:  

Others:

[dzzzzzy]

I have two application, the one is an graphql api application for frontend, the other is a microservice using grpc.

How can I pass the request instance to the rpc call, because I want to use it to show these request trace.

Or is there any way to trace the whole req/res chain?

@kamilmysliwiec Hello kamil, is there any solution for my issue? I am waitting for your reply, thanks a lot!

[woodcockjosh]

@kamilmysliwiec Is this related to this nestjs/nest#747? Will this issue resolve the need to have an example with a separated client and server instead of some hybrid thingy which calls itself?

[josh9060]

Is metadata implemented in nest? Or is it a feature to be added?

If it is implemented, is there any docs on how to use it within nest?

[kamilmysliwiec]

@Joshgallagher it's implemented. There are no docs yet though :(

[josh9060]

@kamilmysliwiec can you point me in the direction of a resource or some sort of rough implementation?

I can make a PR to examples with an example using metadata.

[josh9060]

Also, to clarify:

1. Can we create metadata from a client and send it to the gRPC service?
2. Can we create metadata from the gRPC service itself, for use on the client?

[josh9060]

@kamilmysliwiec Any updates? I'm using MaliJS until metadata is documented in Nest.

[Davide-Gheri]

@Joshgallagher To pass metadata from client to service I found that you need to pass a grpc.Metadata instance as second parameter to the client service call, it doesn't work with plain objects.

const meta = new grpc.Metadata();
meta.set('context', JSON.stringify(ctx));
this.client.getService('SomeService').someMethod(payload, meta);

it seems that the opposite (meta from service to client) is not supported
https://github.com/nestjs/nest/blob/master/packages/microservices/server/server-grpc.ts#L210
I think this is a grpc.sendUnaryData callback that accepts a grpc.Metadata instance as third argument

[sjkummer]

I have a nestjs instance acting as GRPC-Client sending metadata to another nestjs instance that is acting as a GRPC-Server as you described.
But: Seems like the metadata got lost or overwritten somehow.

Edit:
The example above works for me too. Just make sure to use the official grpc.Metadata from https://www.npmjs.com/package/grpc and not accidentally import it from another package.

[guyisra]

Is there an update or a roadmap on this (adding metadata on the service)?

[kerf007]

I have similar issue. I'm as grpc client have to add jwt token to each request to grpc server and I don't understand how to do it. Help please :)

[josh9060]

@kamilmysliwiec Is there any update on the docs providing information on gRPC (nest) microservices returning Metadata?

[sjkummer]

@Joshgallagher I'll recommend to have a look at https://github.com/stephenh/ts-proto and use their NestJS support: https://github.com/stephenh/ts-proto/blob/master/NESTJS.markdown

You'll get all the messages and gRPC call stups generated - including metadata option.

[josh9060]

@sjkummer from my quick glimpse at that package is doesn't add support for gRPC metadata from the server. Correct me if I am wrong though.

[sjkummer]

@Joshgallagher Nestjs already supports gRPC metadata - it's just not well documented, how to declare the methods. You can use generated stubs from ts-proto or write your own declarations by following https://docs.nestjs.com/microservices/grpc

[kwado-tech]

This doc illustrates the use of ts-proto package to generate ts files from .proto schemas.

here is an example script to generate for user.proto schema

# nestJs - /gen-nestjs-proto.sh
generate_nestjs_proto_definitions() {
    # remove directory if exists
    rm -r ./src/proto/nestjs

    # make directory
    mkdir ./src/proto/nestjs

    # generate definitions
    protoc --plugin=./node_modules/.bin/protoc-gen-ts_proto --ts_proto_opt=addGrpcMetadata=true --ts_proto_opt=nestJs=true --ts_proto_out=./src/proto/nestjs ./src/proto/user.proto
}