Worker Services

public class Worker : BackgroundService
{
    private readonly ILogger<Worker> _logger;

    public Worker(ILogger<Worker> logger)
    {
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("Worker starting");

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                _logger.LogInformation("Worker running at: {Time}", DateTimeOffset.Now);
                await DoWorkAsync(stoppingToken);
                await Task.Delay(TimeSpan.FromSeconds(5), stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
                // Graceful shutdown, not an error
                break;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error in worker iteration");
                // Continue or break based on error severity
            }
        }

        _logger.LogInformation("Worker stopping");
    }

    private async Task DoWorkAsync(CancellationToken cancellationToken)
    {
        // Business logic here
    }
}

public class TimedWorker : BackgroundService
{
    private readonly ILogger<TimedWorker> _logger;
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly TimeSpan _period = TimeSpan.FromMinutes(1);

    public TimedWorker(ILogger<TimedWorker> logger, IServiceScopeFactory scopeFactory)
    {
        _logger = logger;
        _scopeFactory = scopeFactory;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        using var timer = new PeriodicTimer(_period);

        while (await timer.WaitForNextTickAsync(stoppingToken))
        {
            try
            {
                await using var scope = _scopeFactory.CreateAsyncScope();
                var processor = scope.ServiceProvider.GetRequiredService<IDataProcessor>();
                await processor.ProcessAsync(stoppingToken);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error processing scheduled task");
            }
        }
    }
}

public class ScopedWorker : BackgroundService
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly ILogger<ScopedWorker> _logger;

    public ScopedWorker(IServiceScopeFactory scopeFactory, ILogger<ScopedWorker> logger)
    {
        _scopeFactory = scopeFactory;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            // Create scope for each unit of work
            await using var scope = _scopeFactory.CreateAsyncScope();

            var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
            var service = scope.ServiceProvider.GetRequiredService<IScopedService>();

            await service.ProcessAsync(dbContext, stoppingToken);
            await Task.Delay(TimeSpan.FromSeconds(10), stoppingToken);
        }
    }
}

public class QueueWorker : BackgroundService
{
    private readonly ILogger<QueueWorker> _logger;
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly IBackgroundTaskQueue _taskQueue;

    public QueueWorker(
        ILogger<QueueWorker> logger,
        IServiceScopeFactory scopeFactory,
        IBackgroundTaskQueue taskQueue)
    {
        _logger = logger;
        _scopeFactory = scopeFactory;
        _taskQueue = taskQueue;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("Queue Worker started");

        while (!stoppingToken.IsCancellationRequested)
        {
            var workItem = await _taskQueue.DequeueAsync(stoppingToken);

            try
            {
                await using var scope = _scopeFactory.CreateAsyncScope();
                await workItem(scope.ServiceProvider, stoppingToken);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error processing queued work item");
                // Handle poison message - retry, dead-letter, etc.
            }
        }
    }
}

// Task queue interface
public interface IBackgroundTaskQueue
{
    ValueTask QueueBackgroundWorkItemAsync(
        Func<IServiceProvider, CancellationToken, ValueTask> workItem);

    ValueTask<Func<IServiceProvider, CancellationToken, ValueTask>> DequeueAsync(
        CancellationToken cancellationToken);
}

// Program.cs
var builder = Host.CreateApplicationBuilder(args);

builder.Services.AddHostedService<Worker>();

// Add health checks
builder.Services.AddHealthChecks()
    .AddCheck<WorkerHealthCheck>("worker_health")
    .AddResourceUtilizationHealthCheck();

// Add HTTP endpoint for health checks
builder.Services.AddHealthChecksUI();

// Or use simple TCP listener for Kubernetes
builder.Services.AddSingleton<TcpHealthProbeService>();
builder.Services.AddHostedService(sp => sp.GetRequiredService<TcpHealthProbeService>());

var host = builder.Build();
host.Run();

public class WorkerHealthCheck : IHealthCheck
{
    private readonly WorkerState _workerState;

    public WorkerHealthCheck(WorkerState workerState)
    {
        _workerState = workerState;
    }

    public Task<HealthCheckResult> CheckHealthAsync(
        HealthCheckContext context,
        CancellationToken cancellationToken = default)
    {
        if (_workerState.LastSuccessfulRun > DateTime.UtcNow.AddMinutes(-5))
        {
            return Task.FromResult(HealthCheckResult.Healthy(
                $"Last successful run: {_workerState.LastSuccessfulRun}"));
        }

        return Task.FromResult(HealthCheckResult.Unhealthy(
            $"No successful run since: {_workerState.LastSuccessfulRun}"));
    }
}

// Shared state
public class WorkerState
{
    public DateTime LastSuccessfulRun { get; set; } = DateTime.UtcNow;
    public bool IsProcessing { get; set; }
}

public class GracefulWorker : BackgroundService
{
    private readonly ILogger<GracefulWorker> _logger;
    private int _currentWorkItemId;

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("Worker starting");

        while (!stoppingToken.IsCancellationRequested)
        {
            _currentWorkItemId = GetNextWorkItemId();

            try
            {
                // Pass cancellation token to all async operations
                await ProcessWorkItemAsync(_currentWorkItemId, stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
                _logger.LogInformation(
                    "Shutdown requested, stopping after work item {Id}", _currentWorkItemId);
                break;
            }
        }
    }

    public override async Task StopAsync(CancellationToken cancellationToken)
    {
        _logger.LogInformation("Worker stopping gracefully");
        await base.StopAsync(cancellationToken);
        _logger.LogInformation("Worker stopped");
    }
}

// Program.cs
var builder = Host.CreateApplicationBuilder(args);

builder.Services.AddWindowsService(options =>
{
    options.ServiceName = "My Worker Service";
});

builder.Services.AddHostedService<Worker>();

var host = builder.Build();
host.Run();

<Project Sdk="Microsoft.NET.Sdk.Worker">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <RuntimeIdentifier>win-x64</RuntimeIdentifier>
    <PublishSingleFile>true</PublishSingleFile>
    <SelfContained>true</SelfContained>
  </PropertyGroup>
</Project>