Add user to the log context when using Serilog and Asp.Net Core

Question

I'm trying to use Serilog together with my ASP.Net Core 1.0 project. I just can't seem to get the current logged in user added to properties logged.

Has anyone figure this out yet?

I have tried this:

using System.Threading.Tasks;
using Serilog.Context;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using System.Security.Claims;
using xxx.Models;

namespace xxx.Utils
{
    public class EnrichSerilogContextMiddleware
    {
        private readonly RequestDelegate _next;
        public EnrichSerilogContextMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext httpContext)
        {

            var username = httpContext.User.Identity.Name;
            if (httpContext.User.Identity.IsAuthenticated)
            {
                var userFullName = (((ClaimsIdentity)httpContext.User.Identity).FindFirst(Member.FullnameClaimName).Value);
                var userName = "[email protected]";
                LoggerEnricher.AddEntryPointContext(userFullName, userName);
            }
            else
            {
                LoggerEnricher.AddEntryPointContext();
            }


            await _next(httpContext);
        }
    }

    public static class LoggerEnricher

    {
        public static void AddEntryPointContext(string userFullName = null, string username = null)
        {
            if (!string.IsNullOrWhiteSpace(username) || !string.IsNullOrWhiteSpace(userFullName))
            {
                LogContext.PushProperty("Username", username);
                LogContext.PushProperty("UserFullename", userFullName);
            }
            else
            {
                LogContext.PushProperty("Username", "Anonymous");
            }

        }

        public static void EnrichLogger(this IApplicationBuilder app)
        {
            app.UseMiddleware<EnrichSerilogContextMiddleware>();
        }
    }
}

I trigger this in Startup.cs by adding:

  public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        loggerFactory.AddConsole(Configuration.GetSection("Logging"));
        loggerFactory.AddDebug();
        loggerFactory.AddSerilog();
        app.EnrichLogger();
        ...
    }

But this always ends up with an "Anonymous" as the Username.

Thanks in advance

Søren Rokkedal

Answer 1

I was able to get the authenticated Active Directory user with just a few lines of code. I'm not very experienced with Core authentication, claims in particular, but perhaps this will get you on your way or at a minimum help others that come along with a similar problem to yours but with AD.

The key lines are Enrich.FromLogContext() and app.Use(async...

public class Startup
{
    public IConfigurationRoot Configuration { get; }

    public Startup(IHostingEnvironment env)
    {
        Log.Logger = new LoggerConfiguration()
                   .Enrich.FromLogContext() // Populates a 'User' property on every log entry
                   .WriteTo.MSSqlServer(Configuration.GetConnectionString("MyDatabase"), "Logs")
                   .CreateLogger();
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        loggerFactory.WithFilter(new FilterLoggerSettings
                                 {
                                     { "Default", LogLevel.Information },
                                     { "Microsoft", LogLevel.Warning },
                                     { "System", LogLevel.Warning }
                                 })
                     .AddSerilog();

        app.Use(async (httpContext, next) =>
                {
                    var userName = httpContext.User.Identity.IsAuthenticated ? httpContext.User.Identity.Name : "unknown";
                    LogContext.PushProperty("User", !String.IsNullOrWhiteSpace(userName) ? userName : "unknown");
                    await next.Invoke();
                });
    }
}

For AD Authentication via IIS/Kestrel the web.config requires a forwardWindowsAuthToken setting as follows:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <aspNetCore ... forwardWindowsAuthToken="true" />
  </system.webServer>
</configuration>