[Extensions.Enrichment.Http] Introduce HTTP client trace enrichment

[evgenyfedorov2]

Design discussion issue #4097.

Changes

Introducing the HTTP client trace enrichment component - OpenTelemetry.Extensions.Enrichment.Http

This is a framework for trace enrichment of outbound HTTP requests. Similar to OpenTelemetry.Extensions.Enrichment, it has an abstract class HttpClientTraceEnricher for .NET:

public abstract class HttpClientTraceEnricher
{
    public virtual void EnrichWithRequest(in TraceEnrichmentBag bag, HttpRequestMessage request) {}
    public virtual void EnrichWithResponse(in TraceEnrichmentBag bag, HttpResponseMessage response) {}
    public virtual void EnrichWithException(in TraceEnrichmentBag bag, Exception exception) {}
}

and for .NET Framework:

public abstract class HttpClientTraceEnricher
{
    public virtual void EnrichWithRequest(in TraceEnrichmentBag bag, HttpWebRequest request) {}
    public virtual void EnrichWithResponse(in TraceEnrichmentBag bag, HttpWebResponse response) {}
    public virtual void EnrichWithException(in TraceEnrichmentBag bag, Exception exception) {}
}

Internally, enrichment is done via the HttpClientTraceEnrichmentProcessor class, which hold references to all registered enrichers and calls Enrich*() methods on each of them.

Developers can add enrichers by calling extension methods either on TracerProviderBuilder or on IServiceCollection:

public static TracerProviderBuilder TryAddHttpClientTraceEnricher<T>(this TracerProviderBuilder builder) where T : HttpClientTraceEnricher;
public static TracerProviderBuilder TryAddHttpClientTraceEnricher(this TracerProviderBuilder builder, HttpClientTraceEnricher enricher);
public static TracerProviderBuilder TryAddHttpClientTraceEnricher<T>(this TracerProviderBuilder builder, Func<IServiceProvider, T> enricherImplementationFactory) where T : HttpClientTraceEnricher;
public static IServiceCollection TryAddHttpClientTraceEnricher<T>(this IServiceCollection services) where T : HttpClientTraceEnricher;
public static IServiceCollection TryAddHttpClientTraceEnricher(this IServiceCollection services, HttpClientTraceEnricher enricher);
public static IServiceCollection TryAddHttpClientTraceEnricher<T>(this IServiceCollection services, Func<IServiceProvider, T> enricherImplementationFactory) where T : HttpClientTraceEnricher;

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

❌ Patch coverage is 94.33962% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.76%. Comparing base (de8dd86) to head (d7f82d8).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...s.Enrichment.Http/Trace/HttpClientTraceEnricher.cs	40.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3082      +/-   ##
==========================================
- Coverage   69.88%   69.76%   -0.12%     
==========================================
  Files         431      436       +5     
  Lines       16671    16724      +53     
==========================================
+ Hits        11651    11668      +17     
- Misses       5020     5056      +36     

Flag	Coverage Δ
unittests-Contrib.Shared.Tests	83.73% <ø> (ø)
unittests-Exporter.Geneva	53.33% <ø> (-0.28%)	⬇️
unittests-Exporter.InfluxDB	95.14% <ø> (ø)
unittests-Exporter.Instana	74.86% <ø> (ø)
unittests-Exporter.OneCollector	94.61% <ø> (ø)
unittests-Extensions	90.65% <ø> (ø)
unittests-Extensions.Enrichment	100.00% <ø> (ø)
unittests-Extensions.Enrichment.AspNetCore	94.11% <ø> (ø)
unittests-Extensions.Enrichment.Http	94.33% <94.33%> (?)
unittests-Instrumentation.AWS	83.80% <ø> (ø)
unittests-Instrumentation.AspNet	74.93% <ø> (ø)
unittests-Instrumentation.AspNetCore	70.76% <ø> (ø)
unittests-Instrumentation.Cassandra	23.52% <ø> (ø)
unittests-Instrumentation.ConfluentKafka	14.10% <ø> (ø)
unittests-Instrumentation.ElasticsearchClient	80.12% <ø> (ø)
unittests-Instrumentation.EntityFrameworkCore	80.80% <ø> (ø)
unittests-Instrumentation.EventCounters	76.36% <ø> (ø)
unittests-Instrumentation.GrpcCore	91.42% <ø> (ø)
unittests-Instrumentation.GrpcNetClient	79.61% <ø> (ø)
unittests-Instrumentation.Hangfire	84.61% <ø> (ø)
unittests-Instrumentation.Http	74.18% <ø> (ø)
unittests-Instrumentation.Owin	88.62% <ø> (ø)
unittests-Instrumentation.Process	100.00% <ø> (ø)
unittests-Instrumentation.Quartz	78.76% <ø> (ø)
unittests-Instrumentation.Runtime	100.00% <ø> (ø)
unittests-Instrumentation.ServiceFabricRemoting	34.54% <ø> (ø)
unittests-Instrumentation.SqlClient	87.29% <ø> (ø)
unittests-Instrumentation.StackExchangeRedis	70.31% <ø> (ø)
unittests-Instrumentation.Wcf	78.95% <ø> (ø)
unittests-OpAmp.Client	68.10% <ø> (+0.93%)	⬆️
unittests-PersistentStorage	65.88% <ø> (-8.03%)	⬇️
unittests-Resources.AWS	74.42% <ø> (ø)
unittests-Resources.Azure	85.31% <ø> (ø)
unittests-Resources.Container	67.34% <ø> (ø)
unittests-Resources.Gcp	71.42% <ø> (ø)
unittests-Resources.Host	73.91% <ø> (ø)
unittests-Resources.OperatingSystem	76.98% <ø> (ø)
unittests-Resources.Process	100.00% <ø> (ø)
unittests-Resources.ProcessRuntime	79.59% <ø> (ø)
unittests-Sampler.AWS	88.25% <ø> (ø)

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

Files with missing lines	Coverage Δ
...HttpClientEnrichmentServiceCollectionExtensions.cs	100.00% <100.00%> (ø)
...ClientEnrichmentTracerProviderBuilderExtensions.cs	100.00% <100.00%> (ø)
.../ConfigureHttpClientTraceInstrumentationOptions.cs	100.00% <100.00%> (ø)
...ttp/Internal/HttpClientTraceEnrichmentProcessor.cs	100.00% <100.00%> (ø)
...s.Enrichment.Http/Trace/HttpClientTraceEnricher.cs	40.00% <40.00%> (ø)

... and 7 files with indirect coverage changes

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[evgenyfedorov2]

@Kielek @rajkumar-rangaraj could you please review this?