Detect aws-sdk-core as well as the monolithic aws-sdk gem

[tobypinder]

See #707

This PR introduces @alksl's workaround from the issue above to detect both monolithic and modular versions of the aws-sdk* gem family. This is important as AWS themselves encourage the more modular approach going forward.

Versions between the "monolithic" and "modular" gems are kept consistent (see aws-sdk-core and aws-sdk) so there shouldn't be any problems with collision.

[tobypinder]

Not sure what's causing the remaining CI failure - it appears to be unrelated.

rspec './spec/ddtrace/contrib/grpc/integration_spec.rb[1:2:1:1]' # gRPC integration test request reply behaves like associates child spans with the parent 
rspec './spec/ddtrace/contrib/grpc/integration_spec.rb[1:4:1:1]' # gRPC integration test server stream behaves like associates child spans with the parent 
rspec ./spec/ddtrace/contrib/grpc/integration_spec.rb:34 # gRPC integration test multiple client configurations uses the correct configuration information

[delner]

Thanks for the contribution @tobypinder! Don't worry about the gRPC test, that flakes out sometimes. I reran it for you.

Just for clarification, our instrumentation as its written will work fine with both the monolith gem or individual modules, as long as they include "core"? Would it make sense to just derive this version from "core" always? (Assuming its part of the monolith?)

[tobypinder]

@delner glad to hear it's unrelated.

My understanding is that the current monolithic gem is just calling the other gems via dependencies:

• aws-sdk
  • aws-sdk-resources
    • aws-*

And that each "resource" (or api type) has a dependency on aws-sdk-core

I think moving to just aws-sdk-core would work, but I think versions of the gem prior to version 2 would then break, as aws "split" the subgems from the monolith beginning with v2. aws-sdk v2 was released September 25, 2014 but I imagine there are still people using it and didn't want to introduce any breaking changes.

[delner]

@tobypinder I think you're right... the latest version of their 1.x branch was released in 2017 and still has well over a million downloads on it, so there's a risk of that breaking compatibility. Given that, I think this is fine as is.

[delner]

Looks good. Thanks for the contribution! 👍