Use GUID as TraceIdentifier in ASP.NET Core Web API

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Background

HttpContext.TraceIdentifier is a unique identifier to represent a request in trace logs. Kestrel generates this ID as {ConnectionId}:{Request number} like 0HLEACIU86PT7:00000005. Now if we want to customize this process, can assign a generated unique id using middleware.

TraceIdentifier Middleware

Middleware

using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;

namespace Cpm.Web.Api.Middlewares
{
    public class TraceIdMiddleware
    {
        private readonly RequestDelegate _next;

        public TraceIdMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext context)
        {
            context.TraceIdentifier = Guid.NewGuid().ToString();
            string id = context.TraceIdentifier;
            context.Response.Headers["X-Trace-Id"] = id;
            await _next(context);
        }
    }
}

Here, we are assigning Guid.NewGuid().ToString() to ccontext.TraceIdentifier and adding the value to the response header as X-Trace-Id.

Use Middleware

Let's use the filter and middleware in Startup.cs or in the bootstrap file. In void Configure(IApplicationBuilder app, IWebHostEnvironment env), add:

/*Middleware*/
app.UseMiddleware<TraceIdMiddleware>();

Testing

Curl

curl -X GET "https://localhost:7178/api/Hello" -H  "accept: text/plain"

Response Headers

content-type: application/json; charset=utf-8 
date: Mon18 Jul 2022 10:25:18 GMT 
server: Kestrel 
x-trace-id: 0c635697-5606-4417-970f-6cdeebbc60ed 

Important

This middleware should be used as the first middleware in the pipeline.

Reference

• How is HttpContext TraceIdentifier generated in .NET Core?

History

• 22^nd July, 2022: Initial version