using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

HostApplicationBuilder builder = Host.CreateApplicationBuilder();
builder.Services.AddHostedService<ABackgroundService>();
builder.Services.AddHostedService<ASlowStartService>();
var host = builder.Build();

var lifetime = host.Services.GetRequiredService<IHostApplicationLifetime>();
_ = host.StartAsync();
await Task.Delay(TimeSpan.FromSeconds(1));
lifetime.StopApplication();
await Task.Delay(TimeSpan.FromSeconds(1));
await host.WaitForShutdownAsync();

internal class ABackgroundService : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        await Task.Delay(Timeout.Infinite, stoppingToken);
    }
}

internal class ASlowStartService : IHostedService
{
    public async Task StartAsync(CancellationToken cancellationToken)
    {
        await Task.Delay(TimeSpan.FromSeconds(10), CancellationToken.None);
    }

    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
}

fail: Microsoft.Extensions.Hosting.Internal.Host[9]
      BackgroundService failed
      System.Threading.Tasks.TaskCanceledException: A task was canceled.
         at ABackgroundService.ExecuteAsync(CancellationToken stoppingToken)
         at Microsoft.Extensions.Hosting.Internal.Host.TryExecuteBackgroundServiceAsync(BackgroundService backgroundService)
crit: Microsoft.Extensions.Hosting.Internal.Host[10]
      The HostOptions.BackgroundServiceExceptionBehavior is configured to StopHost. A BackgroundService has thrown an unhandled exception, and the IHost instance is stopping. To avoid this behavior, configure this to Ignore; however the BackgroundService will not be restarted.
      System.Threading.Tasks.TaskCanceledException: A task was canceled.
         at ABackgroundService.ExecuteAsync(CancellationToken stoppingToken)
         at Microsoft.Extensions.Hosting.Internal.Host.TryExecuteBackgroundServiceAsync(BackgroundService backgroundService)