feat: restructure and support custom sampling

[dylan-asos]

Purpose

This pull request introduces significant changes to the Asos.OpenTelemetry project, focusing on adding custom sampling functionality for OpenTelemetry in ASP.NET Core applications, updating project configurations, and improving documentation. The most important changes include the implementation of route-based sampling, the addition of tests for the new functionality, and updates to project files to target .NET 8.0.

New functionality: Route-based sampling

• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore/Sampling/ConfigurableRouteSampler.cs: Added ConfigurableRouteSampler class to enable route-based sampling using HTTP request paths and methods, with support for custom sampling rates.
• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore/Sampling/RouteSamplingOptions.cs: Introduced RouteSamplingOptions to define sampling rules and a default sampling rate.
• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore/Sampling/SamplingRule.cs: Added SamplingRule class to represent individual sampling rules, including route patterns, HTTP methods, and sampling rates.
• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore/Sampling/OpenTelemetryExtensions.cs: Added extension methods to configure OpenTelemetry with custom sampling rules and integrate Azure Monitor trace exporter.

Unit tests for sampling functionality

• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore.Tests/ConfigurableRouteSamplerTests.cs: Implemented comprehensive tests for ConfigurableRouteSampler, including edge cases like null HTTP context and invalid sampling rates.
• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore.Tests/OpenTelemetrySetupTests.cs: Added tests to verify service registration and correct binding of sampling options in OpenTelemetry setup.

Project updates

• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore/Asos.OpenTelemetry.AspNetCore.csproj: Updated project file to target .NET 8.0 and include metadata for packaging, such as license and documentation files.
• Asos.OpenTelemetry/Asos.OpenTelemetry.Exporter.EventHubs/Asos.OpenTelemetry.Exporter.EventHubs.csproj: Renamed and updated the project file to target .NET 8.0 and simplify metadata paths. [1] [2]

Documentation improvements

• Asos.OpenTelemetry/Asos.OpenTelemetry.AspNetCore/README.md: Added detailed documentation on configuring OpenTelemetry with custom sampling rules, including examples for appsettings.json and usage scenarios.

[Copilot]

Pull Request Overview

This PR restructures the sampling functionality for the Asos.OpenTelemetry project by introducing custom, route-based sampling for ASP.NET Core applications while updating project configurations and documentation for .NET 8.0.

• Added new classes for configuring and processing sampling rules based on HTTP routes and methods.
• Updated project files to target .NET 8.0 and improved README documentation with usage examples.
• Implemented comprehensive unit tests to validate the new custom sampling behavior.

Reviewed Changes

Copilot reviewed 34 out of 34 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
Asos.OpenTelemetry.Exporter.EventHubs.csproj	Updated project targeting to .NET 8.0 and metadata adjustments for packaging
SamplingRule.cs	Added class representing individual sampling rules with regex support
RouteSamplingOptions.cs	Introduced options class to define default and route-specific sampling rates
OpenTelemetryExtensions.cs	Added extension methods to integrate custom sampling with Azure Monitor trace exporter
ConfigurableRouteSampler.cs	Implemented sampler logic based on HTTP request path and method
README.md	Updated documentation to illustrate configuration and usage of custom sampling
OpenTelemetrySetupTests.cs	Added tests for validating service registration and binding of sampling options
ConfigurableRouteSamplerTests.cs	Comprehensive tests for various scenarios of the route-based sampler
Asos.OpenTelemetry.AspNetCore.csproj & Tests.csproj	Updated project files to target .NET 8.0 and align with new features