Example Hosted Service using IHostApplicationLifetime to customize the post-start logic

Program.cs

// ExampleHostedService
class ExampleHostedService : IHostedService
{
    private readonly ILogger _logger;
    private readonly IHostApplicationLifetime _appLifetime;

    public ExampleHostedService(
        ILogger<ExampleHostedService> logger,
        IHostApplicationLifetime appLifetime)
    {
        _logger = logger;
        _appLifetime = appLifetime;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        _appLifetime.ApplicationStarted.Register(OnStarted);
        _appLifetime.ApplicationStopping.Register(OnStopping);
        _appLifetime.ApplicationStopped.Register(OnStopped);

        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        return Task.CompletedTask;
    }

    private void OnStarted()
    {
        _logger.LogInformation("ExampleHostedService: OnStarted has been called.");
        // Perform post-startup activities here
    }

    private void OnStopping()
    {
        _logger.LogInformation("ExampleHostedService: OnStopping has been called.");
        // Perform on-stopping activities here
    }

    private void OnStopped()
    {
        _logger.LogInformation("ExampleHostedService: OnStopped has been called.");
        // Perform post-stopped activities here
    }
}

// Program.cs
class Program
{
  static void Main(string[] args)
  {
      CreateHostBuilder(args).Build().Run();
  }

  static IHostBuilder CreateHostBuilder(string[] args) =>
      Host.CreateDefaultBuilder(args)
          .ConfigureServices((_, services) =>
              services.AddTransient<ITransientGetCreatedTime, GetCreatedTimeImplementation>()
                      .AddScoped<IScopedGetCreatedTime, GetCreatedTimeImplementation>()
                      .AddSingleton<ISingletonGetCreatedTime, GetCreatedTimeImplementation>()
                      .AddTransient<GetCreatedTimeInvoker>()
                      .AddHostedService<ExampleHostedService>());

}