Capture errors with startup hook auto instrumentation #1298

russcam · 2021-05-06T09:22:01Z

This commit updates the startup hook auto instrumentation feature to capture thrown exceptions through the subscribed
AspNetCoreDiagnosticListener.

When an unhandled exception is thrown, ASP.NET Core's DeveloperExceptionPageMiddleware will raise a diagnostic
event with key "Microsoft.AspNetCore.Diagnostics.UnhandledException" if there is a listener listening to the event. If no listener is subscribed, the event is not captured.

Update how assemblies are loaded in the startup hook auto instrumentation. Register an event handler to the AssemblyLoadContext.Default.Resolving event to load assemblies that exist in the loader directory with matching version and public key. For assemblies starting with Elastic.Apm, that may contain DiagnosticListeners, load into AssemblyLoadContext.Default to allow listeners to register via DiagnosticListener.AllListeners.Subscribe(). For any other assemblies, load them into a separate AssemblyLoadContext to avoid version conflicts with assemblies that the application may reference. An example of the problem this avoids is System.Reflection.Metadata; The APM agent's source included version of Ben.Demystifier depends on System.Reflection.Metadata 5.0.0, but an application may reference a different version, such as ASP.NET Core 3.0, which references System.Reflection.Metadata 1.4.4.0 by default.

Add integration tests for capturing errors from startup hooks for netcoreapp3.0, netcoreapp3.1 and net5.0.

Update documentation for startup hooks to indicate that this feature is supported in .NET Core 3.0 and newer. .NET Core 2.2 is End of Life (EOL) and no longer supported by Microsoft. In testing startup hooks with .NET Core 2.2, Diagnostic Listeners do not subscribe to ASP.NET Core diagnostic events. On initial investigation, the System.Diagnostics.DiagnosticSource assembly loaded in the startup hooks is version 4.0.3.1. When listeners come to subscribe, System.Diagnostics.DiagnosticSource 4.0.4.0 that listeners are compiled against is loaded into the separate AssemblyLoadContext, which might be why listeners do not end up subscribing. Considering .NET Core 2.2 is EOL however, no further effort has been put into making this work.

Fixes #1233

This commit updates the startup hook auto instrumentation feature to capture thrown exceptions through the subscribed AspNetCoreDiagnosticListener. When an unhandled exception is thrown, ASP.NET Core's DeveloperExceptionPageMiddleware will raise a diagnostic event with key "Microsoft.AspNetCore.Diagnostics.UnhandledException" if there is a listener listening to the event. If no listener is subscribed, the event is not captured. Update how assemblies are loaded in the startup hook auto instrumentation. Register an event handler to the AssemblyLoadContext.Default.Resolve event to load assemblies that exist in the loader directory with matching version and public key. For assemblies starting with Elastic.Apm, that may contain DiagnosticListeners, load into AssemblyLoadContext.Default to allow listeners to register via DiagnosticListener.AllListeners.Subscribe(). For any other assemblies, load them into a separate AssemblyLoadContext to avoid version conflicts with assemblies that the application may reference. An example of the problem this avoids is System.Reflection.Metadata; The APM agent's source included version of Ben.Demystifier depends on System.Reflection.Metadata 5.0.0, but an application may reference a different version, such as ASP.NET Core 3.0, which references System.Reflection.Metadata 1.4.4.0 by default. Add integration tests for capturing errors from startup hooks for netcoreapp3.0, netcoreapp3.1 and net5.0. Update documentation for startup hooks to indicate that this feature is supported in .NET Core 3.0 and newer. .NET Core 2.2 is End of Life (EOL) and no longer supported by Microsoft. In testing startup hooks with .NET Core 2.2, Diagnostic Listeners do not subscribe to ASP.NET Core diagnostic events. On initial investigation, the System.Diagnostics.DiagnosticSource assembly loaded in the startup hooks is version 4.0.3.1. When listeners come to subscribe, System.Diagnostics.DiagnosticSource 4.0.4.0 that listeners are compiled against is loaded into the separate AssemblyLoadContext, which might be why listeners do not end up subscribing. Considering .NET Core 2.2 is EOL however, no further effort has been put into making this work. Fixes elastic#1233

apmmachine · 2021-05-06T11:27:19Z

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Build Cause: Branch indexing
Start Time: 2021-05-27T02:20:23.321+0000
Duration: 46 min 56 sec
Commit: 5ba3052

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Test	Results
Failed	14
Passed	17596
Skipped	76
Total	17686

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