NLog EventProperties in .NET Core

Question

I'm using ILogger<MyController> to write logs using DI (see step 6)

I'm also using NLog EventProperties

I want to add traceId to all my logs in my controller automatically.

This is working:

logger.Info("Some log. TraceId:{traceId}", 123);

However, then I need to change all my log commands (a lot of them!), which is a pain.

If I do the following, it's not tread safe:

using NLog;
public class MyController : Controller
{
    private static readonly Logger Logger = LogManager.GetCurrentClassLogger();
    public MyConstructor(Apilog apilog)
    {
        Logger.SetProperty("traceid", apilog.TraceId);
    }
}

Is there some way to use SetProperty with ILogger<MyController>?

Or some way of using NLog with SetProperty in a fast and thread safe way?

Many thanks in advance!

Answer 1

When you share loggers between threads, then you could use WithProperty to ensure thread safeness.

Please note that WithProperty/SetProperty is only available on the Logger of NLog. (so not ILogger of Microsoft.Extensions.Logging`). See below.

Example:

using NLog;
public class MyController : Controller
{
    private static readonly Logger BaseLogger = LogManager.GetCurrentClassLogger(); 

    private readonly Logger Logger; // non static because of traceid. 
    public MyConstructor(Apilog apilog)
    {        
        Logger = BaseLogger.WithProperty("traceid", apilog.TraceId);
    }
}

Is there some way to use SetProperty with ILogger<MyController>?

There is no SetProperty on the ILogger interface of Microsoft.Extensions.Logging, but you could do this:

using (_logger.BeginScope(new[] { new KeyValuePair<string, object>("traceid", apilog.TraceId) }))
{
   _logger.LogDebug("Log message");
}

And use in your config: ${mdlc:traceid}. See more details and options here