Nito.Logging

A library for using scopes with Microsoft.Extensions.Logging.

What It Does

This library has two parts:

1. DataScopes provides the BeginDataScope extension methods for ILogger, which allow you to attach name/value pairs of metadata onto your log messages.
2. ExceptionLoggingScope captures logging scopes when an exception is thrown, and applies those logging scopes when the exception is logged. In other words, if you find your exception logs are missing useful information from your logging contexts, install this library and enjoy rich logs again!

Getting Started

First, install the Nito.Logging package.

To attach data scopes to your logs, call BeginDataScope on any ILogger or ILogger<T>. You can pass an anonymous object, any number of (string, object) tuples, or a collection of KeyValuePair<string, object> (such as a Dictionary<string, object>). See the unit tests for examples.

To preserve logging scopes for exceptions:

1. Add a call to AddExceptionLoggingScopes() in your service registration.
2. Call ILogger.BeginCapturedExceptionLoggingScopes(Exception) before logging the exception.

Your service registration will look something like this:

public void ConfigureServices(IServiceCollection services)
{
    services.AddExceptionLoggingScopes();
    ...
}

Your exception logging will look something like this:

// This example uses custom middleware.
// It's also possible to retrieve and log the exception from an error controller if using the standard exception handling middleware.

public class ExceptionLoggingMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger<ExceptionLoggingMiddleware> _logger;

    public ExceptionLoggingMiddleware(RequestDelegate next, ILogger<ExceptionLoggingMiddleware> logger)
    {
        _next = next;
        _logger = logger;
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (Exception ex)
        {
            using (_logger.BeginCapturedExceptionLoggingScopes(ex))
                _logger.Log(ex, "An error occurred.");
            throw;
        }
    }
}

// Don't forget to register the middleware (early in the pipeline):
app.UseMiddleware<ExceptionLoggingMiddleware>();

Alternatives

• Throw context enricher for Serilog - essentially the same as ExceptionLoggingScope, but for Serilog only.