exception_logging_preserve_context.cs

/*
When `LogOperation1` logs the exception, the log record does not contain the properties
of the logging scope that were active at the moment of throwing.
`LogOperation2` has no such issue.
Demo:
❯ dotnet run | grep '^{' | jq 'del(.["@t"], .["@i"], .["@l"], .["@x"], .SourceContext)'
{
  "@m": "Starting operation: \"Fail1\"",
  "OperationName": "Fail1"
}
{
  "@m": "Operation failed: \"Fail1\"",
  "OperationName": "Fail1"
}
{
  "@m": "Starting operation: \"Fail2\"",
  "OperationName": "Fail2"
}
{
  "@m": "Operation failed: \"Fail2\"",
  "OperationName": "Fail2",
  "inner": 42
}

The trick with logging in an exception filter (`when` clause) is used by Serilog, see
https://github.com/serilog/serilog-aspnetcore/blob/dc1181cea495194d86f7ea54c42298d1f805b529/src/Serilog.AspNetCore/AspNetCore/RequestLoggingMiddleware.cs#L69

... but somehow not by Microsoft
https://github.com/dotnet/aspnetcore/blob/81b289460a9ce5fcbd0d32d80a645f139dffc422/src/Middleware/Diagnostics/src/ExceptionHandler/ExceptionHandlerMiddlewareImpl.cs#L103

*/

using Serilog;
using Serilog.Formatting.Compact;
using ILogger = Microsoft.Extensions.Logging.ILogger;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton<MyService>();
builder.Host.UseSerilog((services, lc) => lc
    .Enrich.FromLogContext()
    .WriteTo.Console(new RenderedCompactJsonFormatter()));
var app = builder.Build();
var myService = app.Services.GetRequiredService<MyService>();

try { myService.Fail1(); } catch{}
try { myService.Fail2(); } catch{}

public class MyService {
    private readonly ILogger<MyService> logger;

    public MyService(ILogger<MyService> logger)
    {
        this.logger = logger;
    }

    public int Fail1() => LogHelper.LogOperation1(
        logger,
        () => {
            using var _ = logger.BeginScope(new Dictionary<string, object> {["inner"] = 42});
            throw new Exception("Fail 1");
            return 1;
        }
    );

    public int Fail2() => LogHelper.LogOperation2(
        logger,
        () => {
            using var _ = logger.BeginScope(new Dictionary<string, object> {["inner"] = 42});
            throw new Exception("Fail 2");
            return 1;
        }
    );
}

public static class LogHelper {
    public static T LogOperation1<T>(
        ILogger logger,
        Func<T> action,
        [System.Runtime.CompilerServices.CallerMemberName] string operationName = "")
    {
        try
        {
            logger.LogInformation("Starting operation: {OperationName}", operationName);
            var result = action();
            logger.LogInformation("Operation completed: {OperationName}", operationName);
            return result;
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "Operation failed: {OperationName}", operationName);
            throw;
        }
    }

    public static T LogOperation2<T>(
        ILogger logger,
        Func<T> action,
        [System.Runtime.CompilerServices.CallerMemberName] string operationName = "")
    {
        bool LogException(Exception ex)
        {
            logger.LogError(ex, "Operation failed: {OperationName}", operationName);
            return false;
        }
        try
        {
            logger.LogInformation("Starting operation: {OperationName}", operationName);
            var result = action();
            logger.LogInformation("Operation completed: {OperationName}", operationName);
            return result;
        }
        catch (Exception ex) when (LogException(ex))
        {
            throw;
        }
    }
}