Example request logging middleware for ASP.NET Core

RequestLoggingMiddleware.cs

using System.Diagnostics;

namespace GettingStarted;

class RequestLoggingMiddleware
{
    readonly RequestDelegate _next;
    readonly ILogger _logger;

    public RequestLoggingMiddleware(RequestDelegate next, ILogger<RequestLoggingMiddleware> logger)
    {
        _next = next ?? throw new ArgumentNullException(nameof(next));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task Invoke(HttpContext httpContext)
    {
        if (httpContext == null) throw new ArgumentNullException(nameof(httpContext));

        var start = Stopwatch.GetTimestamp();
        try
        {
            await _next(httpContext);
            var elapsed = Stopwatch.GetElapsedTime(start, Stopwatch.GetTimestamp());
            var statusCode = httpContext.Response.StatusCode;
            LogCompletion(httpContext, statusCode, elapsed, null);
        }
        catch (Exception ex) when (LogCompletion(httpContext, 500, Stopwatch.GetElapsedTime(start, Stopwatch.GetTimestamp()), ex))
        {
        }
    }

    bool LogCompletion(HttpContext httpContext, int statusCode, TimeSpan elapsed, Exception? exception)
    {
        var level = exception != null
            ? LogLevel.Error
            : statusCode > 499
                ? LogLevel.Error
                : LogLevel.Information;
        
        _logger.Log(
            level,
            default,
            exception,
            "HTTP {RequestMethod} {RequestPath} responded {StatusCode} in {Elapsed:0.0000} ms",
            httpContext.Request.Method,
            httpContext.Request.Path,
            statusCode,
            elapsed.TotalMilliseconds);

        return false;
    }
}