Add query execution context based tracing for API requests

[toneymathews]

Closes #4001

An attempt at allowing tracing per request as per suggestions in #4001

• cached_platform_key now accepts the trace phase as a third parameter.
• OpenTelemetryTracing overrides cached_platform_key to access execution context not available in platform_field_key, platform_authorized_key, platform_resolve_type_key

This PR includes

• modified copy of the OpenTelemetry implementation to demonstrate how we would make use of PlatformTracing
• tests to ensure the above works as expected
• a stub for the OpenTelemetry agent

CI has failed due to rubocop failures in files not associated with this PR.

If this looks good, we are hoping to add this to 1.13.x (< 2) since we haven't yet migrated.

[rmosolgo]

Awesome, thanks for sharing this improvement! Yep, I'll backport it to 1.13.x and release a new version there shortly.

[rmosolgo]

🚢 in 1.13.13 !

[toneymathews]

Thanks a lot, much appreciated :)

[ravangen]

🤔 Do you want to maintain OpenTelemetryTracing going forward, or should we leave that to open-telemetry/opentelemetry-ruby?

It was originally included here to demonstrate how everything works together across gems.

[rmosolgo]

Either way works for me 🤷

[ravangen]

I realize you just shipped a release, but I was unsure if we verified/documented how it integrates with opentelemetry in a production environment (e.g. loading its config and tracer). The tests verify behaviour but not integration. I was hoping to follow up this PR with one for opentelemetry-ruby now that cached_platform_key signature was updated.

I'm not sure if/how copyright plays a role in this decision either, we basically forked the original.

IMO we remove OpenTelemetryTracing from graphql-ruby and perhaps the docs link to its existence? Sorry about all this.

[fbogsany]

First-party OpenTelemetry instrumentation is a wonderful thing. We very much want to encourage this. It really should not depend on the OpenTelemetry Ruby auto-instrumentation in any way, though. The goal should be to deprecate the OpenTelemetry auto-instrumentation in favour of first-party instrumentation. There should be no reference to OpenTelemetry::Instrumentation::GraphQL in this repo.

I'll look at the licensing issues, but speaking for myself, I have no problem with copying any of the instrumentation code from the OpenTelemetry Ruby GraphQL auto-instrumentation into this repo, with or without attribution.