feat: AWS X-Ray Remote Sampler Part 1 - Initial Classes and Rules Poller Implementation

[jj22ee]

Description

This is an initial PR to address #1434 in order for OTel Ruby to support X-Ray Remote Sampling. A series of PRs to fully implement this feature will follow this one.

Changes:

• Add new package directory sampler/xray/lib/opentelemetry-sampler-xray.rb
• Updated the OTel Contrib workflow to also run tests for this xray sampler gem
• Code changes:
  • Add Sampling Client class to communicate with X-Ray Service for Sampling Rules/Targets
  • Add X-Ray Sampling Rules/Statistics related classes to help represent the Sampling data from X-Ray
  • Added the AWSXRayRemoteSampler skeleton class
    • Ensure AWSXRayRemoteSampler is a ParentBased Sampler, with internal logic inside InternalAWSXRayRemoteSampler
    • Run poller upon instantiation to regularly obtain X-Ray Sampling Rules from X-Ray

Testing

• Unit Tests
• This PR is not a full implementation of the sampler, so it cannot be tested for correct x-ray sampling functionality.
  Right now, it currently always return a Parent Based decision or a DROP decision as a placeholder.
• A couple more PRs will follow-up to complete the implementation, which should look like this Sampler code from my fork. At that point in the future, a full E2E integration test will be run.

[jj22ee]

@kaylareopelle I've made the initial PR for X-Ray Sampler, will try to get someone from AWS who is familiar with X-Ray Sampling to help with the review.
Just not sure who can help review from OTel Ruby side since this is a new component.

[kaylareopelle]

Hi @jj22ee, sorry about the delay in response on this one. Getting help from someone from AWS with X-Ray sampling experience would be a huge help. I can take care of the review for the parts related to adding new gems to this repo.

[jj22ee]

Will be getting help from @lukeina2z for X-Ray Sampler logic review.

[lukeina2z]

This list does not match service type from the console. Let's say step fn is not listed.

[jj22ee]

We won't include all services that are listed from X-Ray Sampling console. Services like APIGW and StepFn has their own dedicated Sampler logic that cannot be configured with OTel Ruby SDK. So this means we only have to care about the other cases like ebs, ec2, ecs, and eks.

Technically we should exclude Lambda too from this list because Lambda's sampling in not configurable, but I believe we include it in the sampler for all other languages for potential future-proofing for when Lambda may support Remote Sampling.

[kaylareopelle]

Thanks, @lukeina2z for taking a look! And also, thank you, @jj22ee for submitting this PR. Looking forward to the next one!