How to determine which port ASP.NET Core 2 is listening on when a dynamic port (0) was specified

Question

I\'ve got an ASP.NET Core 2.0 app which I intend to run as a stand-alone application. The app should start up and bind to an available port. To achieve this I configure the

Answer 1

You can use the Start() method instead of Run() to access IServerAddressesFeature at the right moment:

IWebHost webHost = new WebHostBuilder()
    .UseKestrel(options => 
         options.Listen(IPAddress.Loopback, 0)) // dynamic port
    .Build();

webHost.Start();

string address = webHost.ServerFeatures
    .Get()
    .Addresses
    .First();
int port = int.Parse(address.Split(':').Last());

webHost.WaitForShutdown();