Add Username into Serilog

问题:

I have this Serilog configuration in program.cs

public class Program
    {
        public static IConfiguration Configuration { get; } = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Production"}.json", optional: true)
            .Build();

        public static void Main(string[] args)
        {
            Log.Logger = new LoggerConfiguration()
                .MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
                .MinimumLevel.Override("System", LogEventLevel.Warning)
                .WriteTo.MSSqlServer(Configuration.GetConnectionString("DefaultConnection"), "dbo.Log")
                .Enrich.WithThreadId()
                .Enrich.WithProperty("Version", "1.0.0")
                .CreateLogger();
            try
            {
                BuildWebHost(args).Run();
            }
            catch (Exception ex)
            {
                Log.Fatal(ex, "Host terminated unexpectedly");
            }
            finally
            {
                Log.CloseAndFlush();
            }

        }

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .UseSerilog()
                .Build();
    }

Now i want to add HttpContext.Current.User.Identity.Name into all log messages.

I tried to create new Enrich class following documentation https://github.com/serilog/serilog/wiki/Configuration-Basics#enrichers

class UsernameEnricher : ILogEventEnricher
    {
        public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory, HttpContext httpContext)
        {
            logEvent.AddPropertyIfAbsent(propertyFactory.CreateProperty(
                    "Username", httpContext.User.Identity.Name));
        }
    }

But there is conflict with ILogEventEnricher which does not know HttpContext.

I also tried to install Nuget package Serilog.Web.Classic which contains Username Enricher, but there is conflict between target framework .Net Framework and .Net Core therefore i cannot use this plugin.

Any idea ?

回答1:

You can create a middleware to put required property to LogContext.

public class LogUserNameMiddleware
{
    private readonly RequestDelegate next;

    public LogUserNameMiddleware(RequestDelegate next)
    {
        this.next = next;
    }

    public Task Invoke(HttpContext context)
    {
        LogContext.PushProperty("UserName", context.User.Identity.Name);

        return next(context);
    }
}

Also you need to add the following to your logger configuration:

.Enrich.FromLogContext()

回答2:

An alternative to using middleware is to use an action filter.

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.Filters;
using Serilog.Context;

namespace Acme.Widgets.Infrastructure
{
    public class LogEnrichmentFilter : IActionFilter
    {
        private readonly IHttpContextAccessor httpContextAccessor;

        public LogEnrichmentFilter(IHttpContextAccessor httpContextAccessor)
        {
            this.httpContextAccessor = httpContextAccessor;
        }

        public void OnActionExecuting(ActionExecutingContext context)
        {
            var httpUser = this.httpContextAccessor.HttpContext.User;

            if (httpUser.Identity.IsAuthenticated)
            {
                var appUser = new AppIdentity(httpUser);
                LogContext.PushProperty("Username", appUser.Username);
            }
            else
            {
                LogContext.PushProperty("Username", "-");
            }
        }

        public void OnActionExecuted(ActionExecutedContext context)
        {
            // Do nothing
        }
    }
}

In your Startup.ConfigureServices you will need to:

1. Ensure IHttpContextAccessor is added to the IoC container
2. Add the LogEnrichmentFilter to the IoC container, scoped to the request
3. Register LogEnrichmentFilter as a global action filter

Startup.cs:

services.TryAddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.AddScoped<LogEnrichmentFilter>();

services.AddMvc(o =>
{
    o.Filters.Add<LogEnrichmentFilter>();
});

You should then have the current username in the log context for code that runs in the MVC action invocation pipeline. I imagine the username would be attached to a few more log entries if you used a resource filter instead of an action filter, as they run slightly earlier in the pipeline (I've only just found out about these!)