opentelemetry-aws: add LambdaResourceDetector

[thomasgouveia]

Changes

This PR introduces the LambdaResourceDetector, which can detect resource attributes from an AWS Lambda environment. A new feature flag has been introduced detector-aws-lambda to hide this code when it is not needed.

It is based on the Go implementation.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

Part of #94

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: thomasgouveia / name: Thomas Gouveia (7320c0d, 75edc86)

[cijothomas]

Thanks for your contribution. I'd request to make this either a standalone crate in this repo, or part of https://github.com/open-telemetry/opentelemetry-rust-contrib/tree/main/opentelemetry-aws

We want to keep any platform specific (AWS/Azure/GCP etc.) outside of the detectors to better ensure ownership, maintenance in the future.

[thomasgouveia]

Hi @cijothomas , no problem, I understand and agree with that vision. What do you think of adding a detector module under opentelemetry-aws? Or should detectors be part of an external crate, such opentelemetry-aws-resource-detectors ?

[cijothomas]

Hi @cijothomas , no problem, I understand and agree with that vision. What do you think of adding a detector module under opentelemetry-aws? Or should detectors be part of an external crate, such opentelemetry-aws-resource-detectors ?

I am unsure if there is any owner for opentelemetry-aws, as it was ported over from the main repo to this repo. We haven't yet established a process for allowing people to own individual crates. I think its best to start by putting detectors inside opentelemetry-aws crate itself for now. (Once we establish a more formal process for ownership, we can extract it to own crate, should the future owners decide to)

[thomasgouveia]

@cijothomas Ok LGTM. I'll do it asap. Thanks!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.4%. Comparing base (56a6f45) to head (7320c0d).
Report is 22 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main     #93     +/-   ##
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+ Coverage   52.3%   56.4%   +4.1%     
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  Files         38      39      +1     
  Lines       4967    5429    +462     
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+ Hits        2598    3064    +466     
+ Misses      2369    2365      -4     

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