contact/Program.cs

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;

namespace contact
{
    public class Program
    {
        //No UseUrls here. The listening address comes from ASPNETCORE_URLS in the systemd unit
        //(http://127.0.0.1:3002) and from launchSettings.json for local runs.
        //The old "only *:3002 works with nginx" comment was F1: nginx proxied to $server_addr, the public IP.
        public static void Main(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(web => web.UseStartup<Startup>())
                .Build()
                .Run();
    }
}