Add DialOptions field to Config struct

[lujiajing1126]

Signed-off-by: Megrez Lu [email protected]

Resolve issue #166

Motivation

In order to connect the inter-process traces between implementations of go-plugin and its peer services, we have to inject the existing tracing context from the client side while extracting context should also be done from the server side.

Design

Server Side

No necessary since we can already do the following, (excerpted from jaeger plugin from our private repository)

			grpc.ServeWithGRPCServer(
				store.NewAliyunSLSStore(&appConfig, logger),
				func(options []googleGRPC.ServerOption) *googleGRPC.Server {
					return plugin.DefaultGRPCServer([]googleGRPC.ServerOption{
						googleGRPC.UnaryInterceptor(otgrpc.OpenTracingServerInterceptor(tracer)),
						googleGRPC.StreamInterceptor(otgrpc.OpenTracingStreamServerInterceptor(tracer)),
					})
				},
			)

Client Side

The only possibility to inject the tracing context is to add grpc.UnaryClientInterceptor or grpc.StreamClientInterceptor as an extra DialOption following the idea from grpc-opentracing,

https://github.com/grpc-ecosystem/grpc-opentracing/blob/master/go/otgrpc/client.go

// OpenTracingClientInterceptor returns a grpc.UnaryClientInterceptor suitable
// for use in a grpc.Dial call.
//
// For example:
//
//     conn, err := grpc.Dial(
//         address,
//         ...,  // (existing DialOptions)
//         grpc.WithUnaryInterceptor(otgrpc.OpenTracingClientInterceptor(tracer)))
//
// All gRPC client spans will inject the OpenTracing SpanContext into the gRPC
// metadata; they will also look in the context.Context for an active
// in-process parent Span and establish a ChildOf reference if such a parent
// Span could be found.

Comments

I am not sure about the Broker module.

[hashicorp-cla]

All committers have signed the CLA.

[tanner-bruce]

@mitchellh @jbardin what would it take to get this merged? We'd like to use this for jaeger as well as grafana. Thanks!

[genert]

CC: @mitchellh @jbardin

[mitchellh]

This looks good, sorry I missed this. I'm going to redo some of the docs but otherwise I'll send this.