Worker.cs

public class Worker : BackgroundService
{
    private readonly ILogger<Worker> _logger;
    private ConnectionFactory _connectionFactory;
    private IConnection _connection;
    private IModel _channel;
    private const string QueueName = "ordering.emailworker";

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

    public override Task StartAsync(CancellationToken cancellationToken)
    {
        _connectionFactory = new ConnectionFactory
        {
            UserName = "ops1",
            Password = "ops1"
        };
        _connection = _connectionFactory.CreateConnection();
        _channel = _connection.CreateModel();
        _channel.QueueDeclarePassive(QueueName);
        _channel.BasicQos(0, 1, false);
        _logger.LogInformation($"Queue [{QueueName}] is waiting for messages.");

        return base.StartAsync(cancellationToken);
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        // listen to the RabbitMQ messages, and send emails
    }

    public override async Task StopAsync(CancellationToken cancellationToken)
    {
        await base.StopAsync(cancellationToken);
        _connection.Close();
        _logger.LogInformation("RabbitMQ connection is closed.");
    }
}