public class PrinterHostedService2 : BackgroundService
{
 private readonly ILogger _logger;
 private readonly AppSettings _settings;

 public PrinterHostedService2(ILoggerFactory loggerFactory, IOptionsSnapshot<AppSettings> options)
 {
 this._logger = loggerFactory.CreateLogger<PrinterHostedService2>();
 this._settings = options.Value;
 }

 public override Task StopAsync(CancellationToken cancellationToken)
 {
 _logger.LogInformation("Printer2 is stopped");
 return Task.CompletedTask;
 }

 protected override async Task ExecuteAsync(CancellationToken stoppingToken)
 {
 while (!stoppingToken.IsCancellationRequested)
 {
  _logger.LogInformation($"Printer2 is working. {_settings.PrinterDelaySecond}");
  await Task.Delay(TimeSpan.FromSeconds(_settings.PrinterDelaySecond), stoppingToken);
 }
 }
}

public class TimerHostedService : BackgroundService
{
 //other ...
 
 private Timer _timer;

 protected override Task ExecuteAsync(CancellationToken stoppingToken)
 {
 _timer = new Timer(DoWork, null, TimeSpan.Zero, TimeSpan.FromSeconds(_settings.TimerPeriod));
 return Task.CompletedTask;
 }

 private void DoWork(object state)
 {
 _logger.LogInformation("Timer is working");
 }

 public override Task StopAsync(CancellationToken cancellationToken)
 {
 _logger.LogInformation("Timer is stopping");
 _timer?.Change(Timeout.Infinite, 0);
 return base.StopAsync(cancellationToken);
 }

 public override void Dispose()
 {
 _timer?.Dispose();
 base.Dispose();
 }
}

class Program
{
 static async Task Main(string[] args)
 {
 var builder = new HostBuilder()
  //logging
  .ConfigureLogging(factory =>
  {
  //use nlog
  factory.AddNLog(new NLogProviderOptions { CaptureMessageTemplates = true, CaptureMessageProperties = true });
  NLog.LogManager.LoadConfiguration("nlog.config");
  })
  //host config
  .ConfigureHostConfiguration(config =>
  {
  //command line
  if (args != null)
  {
   config.AddCommandLine(args);
  }
  })
  //app config
  .ConfigureAppConfiguration((hostContext, config) =>
  {
  var env = hostContext.HostingEnvironment;
  config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
   .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);

  config.AddEnvironmentVariables();

  if (args != null)
  {
   config.AddCommandLine(args);
  }
  })
  //service
  .ConfigureServices((hostContext, services) =>
  {
  services.AddOptions();
  services.Configure<AppSettings>(hostContext.Configuration.GetSection("AppSettings"));

  //basic usage
  services.AddHostedService<PrinterHostedService2>();
  services.AddHostedService<TimerHostedService>();
  }) ;

 //console 
 await builder.RunConsoleAsync();

 ////start and wait for shutdown
 //var host = builder.Build();
 //using (host)
 //{
 // await host.StartAsync();

 // await host.WaitForShutdownAsync();
 //}
 }
}

/// <summary>
/// Listens for Ctrl+C or SIGTERM and calls <see cref="IApplicationLifetime.StopApplication"/> to start the shutdown process.
/// This will unblock extensions like RunAsync and WaitForShutdownAsync.
/// </summary>
/// <param name="hostBuilder">The <see cref="IHostBuilder" /> to configure.</param>
/// <returns>The same instance of the <see cref="IHostBuilder"/> for chaining.</returns>
public static IHostBuilder UseConsoleLifetime(this IHostBuilder hostBuilder)
{
 return hostBuilder.ConfigureServices((context, collection) => collection.AddSingleton<IHostLifetime, ConsoleLifetime>());
}

/// <summary>
/// Enables console support, builds and starts the host, and waits for Ctrl+C or SIGTERM to shut down.
/// </summary>
/// <param name="hostBuilder">The <see cref="IHostBuilder" /> to configure.</param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
public static Task RunConsoleAsync(this IHostBuilder hostBuilder, CancellationToken cancellationToken = default)
{
 return hostBuilder.UseConsoleLifetime().Build().RunAsync(cancellationToken);
}

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xsi:schemaLocation="NLog NLog.xsd"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 autoReload="true"
 internalLogLevel="Info" >

 <targets>
 <target xsi:type="File"
  name="ghost"
  fileName="logs/ghost.log"
  layout="${date}|${level:uppercase=true}|${message}" />
 </targets>

 <rules>
 <logger name="GHost.*" minlevel="Info" writeTo="ghost" />
 <logger name="Microsoft.*" minlevel="Info" writeTo="ghost" />
 </rules>
</nlog>

dotnet run -- --environment Staging

public class ComsumeRabbitMQHostedService : BackgroundService
{
 private readonly ILogger _logger;
 private readonly AppSettings _settings;
 private IConnection _connection;
 private IModel _channel;

 public ComsumeRabbitMQHostedService(ILoggerFactory loggerFactory, IOptionsSnapshot<AppSettings> options)
 {
 this._logger = loggerFactory.CreateLogger<ComsumeRabbitMQHostedService>();
 this._settings = options.Value;
 InitRabbitMQ(this._settings);
 }

 private void InitRabbitMQ(AppSettings settings)
 {
 var factory = new ConnectionFactory { HostName = settings.HostName, };
 _connection = factory.CreateConnection();
 _channel = _connection.CreateModel();

 _channel.ExchangeDeclare(_settings.ExchangeName, ExchangeType.Topic);
 _channel.QueueDeclare(_settings.QueueName, false, false, false, null);
 _channel.QueueBind(_settings.QueueName, _settings.ExchangeName, _settings.RoutingKey, null);
 _channel.BasicQos(0, 1, false);

 _connection.ConnectionShutdown += RabbitMQ_ConnectionShutdown;
 }

 protected override Task ExecuteAsync(CancellationToken stoppingToken)
 {
 stoppingToken.ThrowIfCancellationRequested();

 var consumer = new EventingBasicConsumer(_channel);
 consumer.Received += (ch, ea) =>
 {
  var content = System.Text.Encoding.UTF8.GetString(ea.Body);
  HandleMessage(content);
  _channel.BasicAck(ea.DeliveryTag, false);
 };

 consumer.Shutdown += OnConsumerShutdown;
 consumer.Registered += OnConsumerRegistered;
 consumer.Unregistered += OnConsumerUnregistered;
 consumer.ConsumerCancelled += OnConsumerConsumerCancelled;

 _channel.BasicConsume(_settings.QueueName, false, consumer);
 return Task.CompletedTask;
 }

 private void HandleMessage(string content)
 {
 _logger.LogInformation($"consumer received {content}");
 }
 
 private void OnConsumerConsumerCancelled(object sender, ConsumerEventArgs e) { ... }
 private void OnConsumerUnregistered(object sender, ConsumerEventArgs e) { ... }
 private void OnConsumerRegistered(object sender, ConsumerEventArgs e) { ... }
 private void OnConsumerShutdown(object sender, ShutdownEventArgs e) { ... }
 private void RabbitMQ_ConnectionShutdown(object sender, ShutdownEventArgs e) { ... }

 public override void Dispose()
 {
 _channel.Close();
 _connection.Close();
 base.Dispose();
 }
}

public void ConfigureServices(IServiceCollection services)
{
 services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
 services.AddHostedService<PrinterHostedService2>();
 services.AddHostedService<TimerHostedService>();
 services.AddHostedService<ComsumeRabbitMQHostedService>();
}

vim /etc/systemd/system/ghostdemo.service

[Unit]
Description=Generic Host Demo

[Service]
WorkingDirectory=/var/www/ghost
ExecStart=/usr/bin/dotnet /var/www/ghost/ConsoleGHost.dll --environment Staging
KillSignal=SIGINT
SyslogIdentifier=ghost-example

[Install]
WantedBy=multi-user.target

service ghostdemo start
service ghostdemo stop 

systemctl enable ghostdemo.service

sudo journalctl -fu ghostdemo.service

public class PrinterHostedService : IHostedService, IDisposable
{
 //other ....
 
 public async Task StartAsync(CancellationToken cancellationToken)
 {
  while (!cancellationToken.IsCancellationRequested)
  {
   Console.WriteLine("Printer is working.");
   await Task.Delay(TimeSpan.FromSeconds(_settings.PrinterDelaySecond), cancellationToken);
  }
 }

 public Task StopAsync(CancellationToken cancellationToken)
 {
  Console.WriteLine("Printer is stopped");
  return Task.CompletedTask;
 }
} 

public class PrinterHostedService3 : IHostedService, IDisposable
{
 //others .....
 private bool _stopping;
 private Task _backgroundTask;

 public Task StartAsync(CancellationToken cancellationToken)
 {
  Console.WriteLine("Printer3 is starting.");
  _backgroundTask = BackgroundTask(cancellationToken);
  return Task.CompletedTask;
 }

 private async Task BackgroundTask(CancellationToken cancellationToken)
 {
  while (!_stopping)
  {
   await Task.Delay(TimeSpan.FromSeconds(_settings.PrinterDelaySecond),cancellationToken);
   Console.WriteLine("Printer3 is doing background work.");
  }
 }

 public Task StopAsync(CancellationToken cancellationToken)
 {
  Console.WriteLine("Printer3 is stopping.");
  _stopping = true;
  return Task.CompletedTask;
 }

 public void Dispose()
 {
  Console.WriteLine("Printer3 is disposing.");
 }
}

public static class Extensions
{
 public static IHostBuilder UseHostedService<T>(this IHostBuilder hostBuilder)
  where T : class, IHostedService, IDisposable
 {
  return hostBuilder.ConfigureServices(services =>
   services.AddHostedService<T>());
 }

 public static IHostBuilder UseComsumeRabbitMQ(this IHostBuilder hostBuilder)
 {
  return hostBuilder.ConfigureServices(services =>
     services.AddHostedService<ComsumeRabbitMQHostedService>());
 }
}

var builder = new HostBuilder()
  //others ...
  .ConfigureServices((hostContext, services) =>
  {
   services.AddOptions();
   services.Configure<AppSettings>(hostContext.Configuration.GetSection("AppSettings"));

   //basic usage
   //services.AddHostedService<PrinterHostedService2>();
   //services.AddHostedService<TimerHostedService>();
   //services.AddHostedService<ComsumeRabbitMQHostedService>();
  })
  //extensions usage
  .UseComsumeRabbitMQ()
  .UseHostedService<TimerHostedService>()
  .UseHostedService<PrinterHostedService2>()
  //.UseHostedService<ComsumeRabbitMQHostedService>()
  ;