Allow aliases when requiring instrumented libraries

[seemk]

Instrumentations don't apply hooks when the library name given to require doesn't match instrumentation module definition's name exactly.

Suppose I'm using a package called foobar and I alias it in package.json like this and there exists a FoobarInstrumentation which matches against foobar:

dependencies: {
  "foobar2": "npm:[email protected]"
}

Now when I call require("foobar2") the instrumentation module definition's name, foobar does not match it exactly and the instrumentation is not loaded:
https://github.com/open-telemetry/opentelemetry-js/blob/main/packages/opentelemetry-instrumentation/src/platform/node/instrumentation.ts#L146-L147

Besides aliases it will be useful when testing instrumentations, e.g. it will be possible to have multiple versions of the same library:

devDependencies: {
  "foobar1": "npm:[email protected]",
  "foobar2": "npm:[email protected]",
}

Now the tests will be able to do both require("foobar1") and require("foobar2"), both of them will be instrumented.

• This only affects the JavaScript OpenTelemetry library
• This may affect other libraries, but I would like to get opinions here first

[rauno56]

Playing with the idea a bit further, for that to be implemented, we need to change how we use require-in-the-middle or change require-in-the-middle itself.

1. Change how we use require-in-the-middle. Currently we wrap require every once for every patch fn any instrumentation has. That buries the real require potentially very deep into those calls, makes it difficult to unwrap that later(in fact ritm has a workaround for this, a "soft-unhook") and makes the complexity to match an instrumentation to a require inefficient since all those functions have to be gone through every time in turn.

   What we could do instead is add one _onRequire, let ritm resolve the package for us and then have our own internal logic to find out if the package needs to be patched or not by the version(something we already do) and the actual name in the package.json(something we don't yet do, but since we check the version anyways, adding it would be cheap).

2. Change require-in-the-middle itself. The same idea as above could be pushed into ritm. The root ritm package does not currently inspect package.json(but a dependency might), so it would potentially be an added overhead.

[weyert]

Yeah, great idea, I think this would allow people that forked libraries (e.g. typeorm) and published under a different name to still use the existing instrumentation libraries. E.g. instead of typeorm using @company/typeorm

[mhennoch]

I think this will fix #1391 also

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