[Resources.Gcp] Add Google Cloud Platform resource detector

[matt-hensley]

Changes

Adds Google Cloud Platform resource detector. See package README for published resource attributes.

This package use the new namespace and extension method approach proposed in #1610.

A AddGcpDetector extension method is available for ResourceBuilder.

• Appropriate CHANGELOG.md updated for non-trivial changes
• Design discussion issue #
• Changes in public API reviewed

[codecov]

Codecov Report

Attention: Patch coverage is 72.54902% with 14 lines in your changes are missing coverage. Please review.

Project coverage is 75.97%. Comparing base (71655ce) to head (bd37f89).
Report is 236 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1691      +/-   ##
==========================================
+ Coverage   73.91%   75.97%   +2.05%     
==========================================
  Files         267      297      +30     
  Lines        9615    11557    +1942     
==========================================
+ Hits         7107     8780    +1673     
- Misses       2508     2777     +269     

Flag	Coverage Δ
unittests-Exporter.Geneva	64.22% <ø> (?)
unittests-Exporter.OneCollector	89.72% <ø> (?)
unittests-Extensions	79.33% <ø> (?)
unittests-Instrumentation.AspNet	74.39% <ø> (?)
unittests-Instrumentation.AspNetCore	85.27% <ø> (?)
unittests-Instrumentation.EventCounters	76.36% <ø> (?)
unittests-Instrumentation.GrpcNetClient	81.96% <ø> (?)
unittests-Instrumentation.Http	81.91% <ø> (?)
unittests-Instrumentation.Owin	83.43% <ø> (?)
unittests-Instrumentation.Process	100.00% <ø> (?)
unittests-Instrumentation.Runtime	100.00% <ø> (?)
unittests-Instrumentation.SqlClient	90.90% <ø> (?)
unittests-Instrumentation.StackExchangeRedis	71.00% <ø> (?)
unittests-Instrumentation.Wcf	78.47% <ø> (?)
unittests-PersistentStorage	65.78% <ø> (?)
unittests-ResourceDetectors.Azure	81.53% <ø> (?)
unittests-ResourceDetectors.Host	54.11% <ø> (?)
unittests-ResourceDetectors.Process	100.00% <ø> (?)
unittests-ResourceDetectors.ProcessRuntime	76.08% <ø> (?)
unittests-Resources.Gcp	72.54% <72.54%> (?)
unittests-Solution	79.13% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...etry.Resources.Gcp/GcpResourceBuilderExtensions.cs	0.00% <0.00%> (ø)
...OpenTelemetry.Resources.Gcp/GcpResourceDetector.cs	75.51% <75.51%> (ø)

... and 280 files with indirect coverage changes

[Kielek]

LGTM.

@CodeBlanch, could you please review public API?

[CodeBlanch]

Should extensions go into the namespace of the thing they are extending or somewhere else?

We have had debates about this in the past so I thought I would drop a comment here to make it known this was an intentional decision.

.NET guidelines say this:

I would argue these packages/extensions are all about dependency management for users so this gets a 👍 from me.

[matt-hensley]

Most of the instrumentations put their extension methods in the namespace for the type they're extending (ex. OpenTelemetry.Trace, OpenTelemetry.Metrics), so would fit unless the other extension methods are going to be moved.

[CodeBlanch]

The public API LGTM. This whole PR is very nicely done! I ❤️ using OpenTelemetry.Resources in the namespace and the package name.

I haven't approved just yet because I asked @alanwest to also take a look. Because he was originally leading the charge for better package names (open-telemetry/opentelemetry-dotnet#3469).

[alanwest]

I ❤️ using OpenTelemetry.Resources in the namespace and the package name.

I don't mind if we change course on this, but is the plan to rename the existing packages to OpenTelemetry.Resources.*?

[Kielek]

I ❤️ using OpenTelemetry.Resources in the namespace and the package name.

I don't mind if we change course on this, but is the plan to rename the existing packages to OpenTelemetry.Resources.*?

Yes. #1610

[CodeBlanch]

LGTM