New relic TraceId Not getting poplulated in .net core middleware

[cpr4377]

New relic TraceId Not getting poplulated in .net core middleware.

Description
I am trying to access the newrelic traceid in asp.net core middleware and pass it as a response header in the response.

Please see the implementation below :

`public sealed class TraceIdMiddleware
{
       private readonly RequestDelegate _next;
       private readonly ILogger<TraceIdMiddleware> _logger;

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

   public async Task InvokeAsync(HttpContext context)
   {
       if (!context.Request.Headers.ContainsKey("X-Trace-Id"))
       {
           var tracer = NewRelic.Api.Agent.NewRelic.GetAgent();
           var traceId = tracer.TraceMetadata.TraceId;
           
           _logger.LogWarning("NewRelic Trace Id " + traceId);
           _logger.LogWarning("Http context trace Id " + context.TraceIdentifier);
         
           if (!string.IsNullOrEmpty(traceId))
           {
               context.Response.Headers.Append("X-Trace-Id", traceId);
           }
       }
       await _next(context);
   }
   }`

But the trace id is always coming as empty . The agent is running and distributed tracing is enabled, still the issue persist. Has anyone encountered this issue ?

Expected Behavior
Traceid should not be coming empty

Using the latest agent and latest donet newrelic api

[workato-integration]

https://new-relic.atlassian.net/browse/NR-305595

[tippmar-nr]

Thanks @cpr4377 for your bug report.

I created a simple test app targeting .NET 8 (using the default Web API app from Visual Studio), added your middleware code and ran some tests. The NewRelic trace id was generated for each request:

How are you adding the middleware to the asp.net core request pipeline? The .NET agent injects our middleware at the very beginning of the request pipeline, so if you're doing anything other than just calling app.UseMiddleware<TraceIdMiddleware>(), it's possible you're interfering with the agent's middleware injection.

I'm going to close this bug since I can't reproduce it, but if you have further information that would help reproduce it, feel free to re-open and provide a repro app.

Here's my repro app (not including the bits generated by Visual Studio for the Web API sample app):

{
    public class Program
    {
        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);

            // Add services to the container.
            builder.Services.AddControllers();
            var app = builder.Build();

            // Configure the HTTP request pipeline.

            app.UseAuthorization();
            app.UseMiddleware<TraceIdMiddleware>();

            app.MapControllers();

            app.Run();
        }
    }

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

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

        public async Task InvokeAsync(HttpContext context)
        {
            if (!context.Request.Headers.ContainsKey("X-Trace-Id"))
            {
                var tracer = NewRelic.Api.Agent.NewRelic.GetAgent();
                var traceId = tracer.TraceMetadata.TraceId;

                _logger.LogWarning("NewRelic Trace Id " + traceId);
                _logger.LogWarning("Http context trace Id " + context.TraceIdentifier);

                if (!string.IsNullOrEmpty(traceId))
                {
                    context.Response.Headers.Append("X-Trace-Id", traceId);
                }
            }
            await _next(context);
        }
    }
}