ASP.NET Core : open browser on start, and stop server from browser.

Program.cs

// This exemple shows :
// * how to start an app with a free local port
// * how to find urls used and open a brower
// * how to stop the server
//
// Of course it's not production ready, it's a simple howto/reminder.
//
// Some part are come from :
// https://andrewlock.net/how-to-automatically-choose-a-free-port-in-asp-net-core/

using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Hosting.Server.Features;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace LocalAndEphemeralAspNetCore
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Program>();
                    webBuilder.UseUrls("http://127.0.0.1:0;https://127.0.0.1:0");
                });

        public void ConfigureServices(IServiceCollection services)
        {
        }

        public void Configure(IApplicationBuilder app,
                              IWebHostEnvironment env,
                              IHostApplicationLifetime lifetime,
                              ILogger<Program> logger)
        {
            lifetime.ApplicationStarted.Register(() =>
            {
                var url = FindUrl(app.ServerFeatures, logger);
                if (url is not null)
                {
                    OpenBrowser(url);
                }
            });

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapGet("/", async context =>
                {
                    await context.Response.WriteAsync("Hello World!");
                });

                endpoints.MapGet("/stop", context =>
                {
                    lifetime.StopApplication();
                    return Task.CompletedTask;
                });
            });
        }

        public string FindUrl(IFeatureCollection features, ILogger logger)
        {
            var addressFeature = features.Get<IServerAddressesFeature>();
            string UrlToOpen = null;

            foreach (var address in addressFeature.Addresses)
            {
                logger.LogInformation("Listening on address: " + address);
                if (address.StartsWith("https://127.0.0.1:"))
                {
                    UrlToOpen = address;
                }
            }

            return UrlToOpen;
        }

        public void OpenBrowser(string url)
        {
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
            {
                Process.Start(new ProcessStartInfo("cmd", $"/c start {url}"));
            }
            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
            {
                Process.Start("xdg-open", url);
            }
            else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
            {
                Process.Start("open", url);
            }
        }
    }
}