Check out this blog post if you want to get the full public URL of your ASP.NET Core application, or this blog post if you want to generate absolute URLs for your ASP.NET Core application.
There are many ways to configure the URLs ASP.NET Core will try binding to. Here's a couple of ways: - You can programmatically configure the URLs using the UseUrls method. - You can use the `--urls` argument like this `dotnet run --urls "http://localhost:8080"`. - You can configure the URL with the `ASPNETCORE_URLS` environment variable. - Out of the box, the web templates will create a JSON file *Properties/launchSettings.json* which holds multiple profiles to run your application. In that JSON file, you can change the `applicationUrl` property to configure which URL ASP.NET Core will bind to. There are also other ways to set the URLs using JSON configuration. You could try to programmatically check each one of these variations to see which URLs will be used, but there are multiple built-in APIs you can use to get these URLs. ## How to get ASP.NET Core server URLs in Program.cs with minimal APIs {#how-to-get-aspnet-core-server-urls-in-programcs-with-minimal-apis} Here's how you could access the URLs in .NET 6's minimal API Program.cs file:var builder = WebApplication.CreateBuilder(args); var app = builder.Build(); app.MapGet("/", () => "Hello World!"); Console.WriteLine($"Urls from Program.cs before app.StartAsync(): {string.Join(", ", app.Urls)}"); await app.StartAsync(); Console.WriteLine($"Urls from Program.cs after app.StartAsync(): {string.Join(", ", app.Urls)}"); await app.WaitForShutdownAsync();Here's what the output looks like:
Urls from Program.cs before app.StartAsync():
info: Microsoft.Hosting.Lifetime[14]
Now listening on: https://localhost:7227
info: Microsoft.Hosting.Lifetime[14]
Now listening on: http://localhost:5227
info: Microsoft.Hosting.Lifetime[0]
Application started. Press Ctrl+C to shut down.
Urls from Program.cs after app.StartAsync(): https://localhost:7227, http://localhost:5227
You can get the URLs via the `app.Urls` property, but only after the application has been started.using Microsoft.AspNetCore.Hosting.Server; using Microsoft.AspNetCore.Hosting.Server.Features; using Microsoft.AspNetCore.Mvc; public class HomeController : Controller { private readonly IServer server; public HomeController(IServer server) { this.server = server; } public IActionResult Index() { var addresses = server.Features.Get<IServerAddressesFeature>().Addresses; Console.WriteLine($"Addresses from HomeController.Index: {string.Join(", ", addresses)}"); return View(); } }You can have the `IServer` object injected through your constructor, and then get the `IServerAddressesFeature` feature.
Addresses from HomeController.Index: https://localhost:7187, http://localhost:5187
The Addresses collection will be empty if the server application hasn't started yet. You don't have to worry about that inside of a Controller because the controllers won't be invoked until the server has been started yet. But if you try to get address outside of Razor Pages, MVC controllers, or endpoints, you'll have to make sure the server has been started before getting the URLs.
So, what do you do if the server application hasn't started yet? Let's look at another example.
using Microsoft.AspNetCore.Hosting.Server; using Microsoft.AspNetCore.Hosting.Server.Features; public class MyHostedService : IHostedService { private readonly IServer server; private readonly IHostApplicationLifetime hostApplicationLifetime; public MyHostedService(IServer server, IHostApplicationLifetime hostApplicationLifetime) { this.server = server; this.hostApplicationLifetime = hostApplicationLifetime; } public Task StartAsync(CancellationToken cancellationToken) { Console.WriteLine($"Addresses before application has started: {GetAddresses()}"); hostApplicationLifetime.ApplicationStarted.Register( () => Console.WriteLine($"Addresses after application has started: {GetAddresses()}")); return Task.CompletedTask; } private string GetAddresses() { var addresses = server.Features.Get<IServerAddressesFeature>().Addresses; return string.Join(", ", addresses); } public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask; }You can receive an instance of `IHostApplicationLifetime` through constructor dependency injection, and then use it in `StartAsync` to hook into its lifecycle events.
Addresses before application has started: Addresses after application has started: https://localhost:7012, http://localhost:5012You can also do this in the `ExecuteAsync` method if you use a `BackgroundService`:
using Microsoft.AspNetCore.Hosting.Server; using Microsoft.AspNetCore.Hosting.Server.Features; public class MyBackgroundService : BackgroundService { private readonly IServer server; private readonly IHostApplicationLifetime hostApplicationLifetime; public MyBackgroundService(IServer server, IHostApplicationLifetime hostApplicationLifetime) { this.server = server; this.hostApplicationLifetime = hostApplicationLifetime; } protected override async Task ExecuteAsync(CancellationToken stoppingToken) { Console.WriteLine($"Addresses before application has started: {GetAddresses()}"); await WaitForApplicationStarted(); Console.WriteLine($"Addresses after application has started: {GetAddresses()}"); } private string GetAddresses() { var addresses = server.Features.Get<IServerAddressesFeature>().Addresses; return string.Join(", ", addresses); } private Task WaitForApplicationStarted() { var completionSource = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously); hostApplicationLifetime.ApplicationStarted.Register(() => completionSource.TrySetResult()); return completionSource.Task; } }In `BackgroundService.ExecuteAsync` you can properly wait by awaiting a task. Unfortunately, in `IHostedService.StartAsync` you cannot do this because the application builder will wait for your hosted service to start, but your hosted service would wait for the application to start, in which case neither ever finish starting. This is probably a less common use case, but being able to access the URLs can come in really useful. For example, you can use these [URLs to automatically start a ngrok tunnel and use the tunnel to respond to webhooks which I wrote about for the Twilio blog](https://www.twilio.com/blog/integrate-ngrok-into-aspdotnet-core-startup-and-automatically-update-your-webhook-urls)! **I'm curious to know how you'll be using these URLs, let me know!**