instrumentation-grpc: Undefined path attribute in clientMethodTrace

[jorgelbg]

What version of OpenTelemetry are you using?

0.19.0 from the main branch

What version of Node are you using?

v14.16.1 / macOS 10.15.7

Please provide the code you used to setup the OpenTelemetry SDK

example from examples/grpc.

What did you do?

Running the grpc instrumentation example:

# shell 1
npm run zipkin:server

and

# shell 2
npm run zipkin:client

What did you expect to see?

I expected the example using the instrumentation-grpc library to work similarly to the plugin-grpc one.

What did you see instead?

❯❯❯ npm run zipkin:client

> grpc-example@0.19.0 zipkin:client
> cross-env EXPORTER=zipkin node ./client.js

Client traceId  18602ad094e9fb4f943f9031aac4eb54
/Users/jbetancourt/Code/opentelemetry-js/examples/grpc/node_modules/@opentelemetry/instrumentation-grpc/build/src/grpc/index.js:170
                const name = `grpc.${original.path.replace('/', '')}`;
                                                   ^

TypeError: Cannot read property 'replace' of undefined
    at ServiceClient.clientMethodTrace [as sayHello] (/Users/jbetancourt/Code/opentelemetry-js/examples/grpc/node_modules/@opentelemetry/instrumentation-grpc/build/src/grpc/index.js:170:52)
    at /Users/jbetancourt/Code/opentelemetry-js/examples/grpc/client.js:33:12
    at async_hooks.js:313:14
    at AsyncResource.runInAsyncScope (async_hooks.js:197:9)
    at AsyncLocalStorage.run (async_hooks.js:311:35)
    at AsyncLocalStorageContextManager.with (/Users/jbetancourt/Code/opentelemetry-js/examples/grpc/node_modules/@opentelemetry/context-async-hooks/build/src/AsyncLocalStorageContextManager.js:33:40)
    at ContextAPI.with (/Users/jbetancourt/Code/opentelemetry-js/examples/grpc/node_modules/@opentelemetry/api/build/src/api/context.js:71:54)
    at main (/Users/jbetancourt/Code/opentelemetry-js/examples/grpc/client.js:18:19)
    at Object.<anonymous> (/Users/jbetancourt/Code/opentelemetry-js/examples/grpc/client.js:47:1)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)

Additional context

We ran into the same issue in a bigger project that uses (among other things) Apollo for providing a GraphQL server. We were trying to remove the old plugins in favor of the new instrumentation libraries.

Initially, we thought that the issue was related to something specific about our project but I was able to reproduce it with the code from examples/grpc.

[dyladan]

Closed in #2179