This example uses the same gRPC defs.proto as the grpc_dynamic_codegen example in which a server takes a payload containing bytes and capitalizes them. In this case we are demonstrating the use of the propagator-grpc-census-binary propagator. The propagator can be useful when communicating with another service that is already instrumented using OpenCensus.
If both sides of gRPC communication are using OpenTelemetry instrumentation then
the propagator-grpc-census-binary propagator isn't required. Context will be
propagated using the traceparent header (thanks to the
HttpTraceContextPropagator
propagator from opentelemetry-core). If there is a mix of OpenCensus and OpenTelemetry
instrumentation then the propagator-grpc-census-binary propagator allows OpenTelemetry
to propagate context through the grpc-trace-bin binary header.
The same source code is used to run various versions of the client and server. Environment
variables (set up through scripts in package.json) determine the various
combinations. This table shows what to expect:
| Combination | Client Instrumentation | Server Instrumentation | Propagation Header |
|---|---|---|---|
| 1 | OpenTelemetry (default propagator) | OpenTelemetry (default propagator) | traceparent |
| 2 | OpenCensus | OpenTelemetry (binary propagator) | grpc-trace-bin |
| 3 | OpenCensus | OpenCensus | grpc-trace-bin |
| 4 | OpenTelemetry (binary propagator) | OpenCensus | grpc-trace-bin |
If context propagation is working correctly we should see consistent values
for traceId in the output of both the client and server. (Note: the example
uses simple Console Exporters rather than Jaeger or Zipkin). The servers also
output the contents of grpc.Metadata which allows us to see the values of
traceparent or grpc-trace-bin where applicable.
$ # from this directory
$ npm installOpenTelemetry (with default propagator) used on both client and server.
Propagation through traceparent header.
-
Run the server
$ # from this directory $ npm run server:otel:defprop -
Run the client
$ # from this directory $ npm run client:otel:defprop
OpenTelemetry (with binary propagator) used on server, OpenCensus used
on client. Propagation through grpc-trace-bin header.
-
Run the server
$ # from this directory $ npm run server:otel:binprop -
Run the client
$ # from this directory $ npm run client:census
See combination2 for example output
OpenCensus used on both client and server. Propagation through grpc-trace-bin header.
-
Run the server
$ # from this directory $ npm run server:census -
Run the client
$ # from this directory $ npm run client:census
OpenCensus used on server, OpenTelemetry (with binary propagator) used on
client. Propagation through grpc-trace-bin header.
-
Run the server
$ # from this directory $ npm run server:census -
Run the client
$ # from this directory $ npm run client:otel:binprop
See combination4 for example output
- For more information on OpenTelemetry, visit: https://opentelemetry.io/
- For more information on OpenTelemetry for Node.js, visit: https://github.com/open-telemetry/opentelemetry-js/tree/main/packages/opentelemetry-node-sdk
Apache License 2.0