feat(instrumentation-aws-lambda): support ESM handlers and other less common handler patterns

[raphael-theriault-swi]

Which problem is this PR solving?

The Lambda instrumentation doesn't currently support instrumenting ESM handlers, which are now the default, and other less common handler patterns supported by Lambda such as extensionless handler modules and nested handler functions.

Short description of the changes

The previous logic to determine the handler to patch is replaced with an implementation based on the one present in the Lambda runtime. I tried to keep the function names and structure as close to possible to the original to make it easier to cross-reference.

The tests also now use code copied from the Lambda runtime to load handlers, as opposed to just calling require which doesn't properly reflect a real-world scenario and doesn't work at all for ESM.

I also updated the notes about absolute path support in the patching infrastructure. The instrumentation keeps using the same hack but it would probably be a good idea to fix the issue upstream, which is that while absolute paths are taken into account while registering hooks, they are not when matching against the module name within the hook function, which ignores the baseDir.

[codecov]

Codecov Report

Attention: Patch coverage is 97.43590% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.66%. Comparing base (80d0c74) to head (cf7d4c3).

Files with missing lines	Patch %	Lines
...-instrumentation-aws-lambda/src/instrumentation.ts	97.05%	1 Missing ⚠️
...ry-instrumentation-aws-lambda/src/user-function.ts	97.72%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2000      +/-   ##
==========================================
- Coverage   90.79%   90.66%   -0.14%     
==========================================
  Files         169      165       -4     
  Lines        8009     7757     -252     
  Branches     1632     1610      -22     
==========================================
- Hits         7272     7033     -239     
+ Misses        737      724      -13     

Files with missing lines	Coverage Δ
...-instrumentation-aws-lambda/src/instrumentation.ts	95.02% <97.05%> (+0.44%)	⬆️
...ry-instrumentation-aws-lambda/src/user-function.ts	97.72% <97.72%> (ø)

... and 7 files with indirect coverage changes

[raphael-theriault-swi]

@JamieDanielson I think you've been pushing a lot for ESM support as a whole, if I rebased this do you think you'd be able to take a look ?

[raphael-theriault-swi]

@jj22ee a review would be much appreciated when you have some time

[jj22ee]

Hi, I see that there have been merged changes recently to support ESM handlers while not changing the implementation in instrumentation-aws-lambda. There are fixes related to the issue of baseDir.

• Looking for help: not receiving any trace data from collector opentelemetry-lambda#1557 (comment)

It looks like that ESM handlers will be supported once all these changes are released in the latest OTel JS version.
Would your changes still be needed after this?

[raphael-theriault-swi]

The changes wouldn't be needed for ESM support no, and this PR could be updated to take advantage of proper support for absolute path. I'd personally argue for still merging given it supports strictly more valid handler patterns and properly tests support for ESM (which the merged PR did not) and these other patterns.

@trentm sorry to ping you for the 10th time the past couple days, but as the reviewer of the ESM support PR do you have any thoughts wrt what to do with this one ?

[pragmaticivan]

cc @tylerbenson @serkan-ozal @mchiaramonte