CorrelationIdMiddleware.cs

using System.Diagnostics;
using Serilog.Context;

public class CorrelationIdMiddleware
{
    private readonly RequestDelegate _next;

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

    public async Task InvokeAsync(HttpContext context)
    {
        var correlationId = context.Request.Headers["X-Correlation-ID"].FirstOrDefault() ?? Activity.Current?.Id ?? Guid.NewGuid().ToString();
        context.Items["CorrelationId"] = correlationId;

        using (LogContext.PushProperty("CorrelationId", correlationId))
        {
            context.Response.OnStarting(() =>
            {
                context.Response.Headers.Append("X-Correlation-ID", correlationId);
                return Task.CompletedTask;
            });

            await _next(context);
        }
    }
}

public static class CorrelationIdMiddlewareExtensions
{
    public static IApplicationBuilder UseCorrelationId(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<CorrelationIdMiddleware>();
    }
}