Get First Kestrel Endpoint Address

Startup.cs

// Type: Microsoft.AspNetCore.Hosting.Server.Features.IServerAddressesFeature
// Assembly: Microsoft.AspNetCore.Hosting.Server.Abstractions, Version=2.2.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60
// using Microsoft.AspNetCore.Hosting.Server.Features;

public void Configure(IApplicationBuilder app)
{
  var address = app.ServerFeatures
    .Select(i => i.Value)
    .OfType<IServerAddressesFeature>()
    .SelectMany(f => f.Addresses)
    .First();
}