How to configure NLog to get IP address .NET Core

It is now easier: Introduced in NLog Web.AspNetCore 4.4.0 & NLog.Web 4.5.0

Render Client IP address

Supported in ASP.NET & ASP.NET Core.

Configuration Syntax

${aspnet-request-ip}

Nothing else is needed

This is supported since NLog.Web.AspNetCore 4.4.0.

1. Install the package NLog.Web.AspNetCore

2. Set in your config

   <!-- enable asp.net core layout renderers -->
   <extensions>
     <add assembly="NLog.Web.AspNetCore"/>
   </extensions>
   

3. You could now use ${aspnet-request-ip} in your config.

PS: also supported for ASP.NET in NLog.Web 4.5.0

Old answer

Currently this is not supported, but you could inject it in NLog like this:

using System;
using System.Text;
using Microsoft.AspNetCore.Http;
using NLog.Config;
using NLog.LayoutRenderers;
using NLog.Web.Internal;

namespace NLog.Web.LayoutRenderers
{
    /// <summary>
    /// Render the request IP for ASP.NET Core
    /// </summary>
    /// <example>
    /// <code lang="NLog Layout Renderer">
    /// ${aspnet-request-ip}
    /// </code>
    /// </example>
    [LayoutRenderer("aspnet-request-ip")]
    public class AspNetRequestIpLayoutRenderer : AspNetLayoutRendererBase
    {

        protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
        {
            var httpContext = HttpContextAccessor.HttpContext;
            if (httpContext == null)
            {
                return;
            }
            builder.Append(httpContext.Connection.RemoteIpAddress);
        }
    }
}

Register it (startup.cs)

ConfigurationItemFactory.Default.LayoutRenderers
    .RegisterDefinition("aspnet-request-ip", typeof(AspNetRequestIpLayoutRenderer));

See also Extending NLog

usage

${aspnet-request-ip}

Also include NLog.Web.AspNetCore!