Program.CreateHostBuilder

program-create-host-builder.cs

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

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureServices((hostContext, services) =>
            {
                // Add event processor
                services.AddSingleton<IEventProcessor>(sp =>
                {
                    // Create Kafka consumer and producer
                    var kafkaConsumer = KafkaUtils.CreateConsumer("localhost:9092", new List<string> { "raw-events" });
                    var kafkaProducer = KafkaUtils.CreateProducer("localhost:9092");

                    // Create handlers
                    var handlers = new List<MessageHandler> { new TransformHandler() };

                    // Create event processor
                    return new KafkaEventProcessor<int, string, int, string>(
                        new KafkaEventConsumer<int, string>(kafkaConsumer),
                        new KafkaEventProducer<int, string>(kafkaProducer, "processed-events"),
                        handlers.ToArray());
                });
                services.AddHostedService<Worker>();
            });
}