Context cannot be transferred across services

[Tiper-In-Github]

description

I tried passing the context in RPC() and RPCTo() in V2, but the receiving end always received an empty context. I checked the context when sending through a breakpoint and confirmed that it contained the information I expected. Is this by design or an exception？ (💡which prevents me from using opentelemetry to track links across services)

Code Snippet：

// Send
newCtx = context.WithValue(newCtx, "Test", "119991")
if err := app.RPC(newCtx, "Preview.Remote.sync", rpcResp, rpcReq); err != nil {
  logger.Log.Errorf("%v%v rpcFail:", logPrefix, err.Error())
  span.AddEvent("rpcFail:" + err.Error())
  return false
}

// Receiver
func (r *PreviewRemoteHandler) Sync(c context.Context, req *rpcProtobuf.ReqSync) (*rpcProtobuf.RespSync, error) {
    logger.Log.Infof("test context:%v", c.Value("Test"))
        ......
}

Expected results:

test context:119991

Actual results:

test context:<nil>

[Tiper-In-Github]

@felipejfc Hope to see this issue soon

[felipejfc]

You're right, ctx is currently not propagated. However, there's default integration with Opentelemetry already in master branch. See the docs. Here If you want to propagate more values between calls you can use the "Propagated Context" utility which is the same one we use for default opentelemetry integration. See here https://github.com/topfreegames/pitaya/blob/main/pkg/context/context.go#L30-L44

[Tiper-In-Github]

Thanks,In the future, are there plans to support propagation to enable cross-service link tracking?

[felipejfc]

Can you be more specific about which kind of key/values you will be propagating? Also, does this manual propagation method fits your needs?

I'm thinking about a more transparent way of context propagation that will happen automatically, so gathering some info on use cases would be helpful

[Tiper-In-Github]

We hope to use OpenTelemetry while passing the engine's existing 'request_id' to provide more detailed and convenient tracking and logging.Since we are using V2, we are connecting to opentelemetry ourselves