using symfony dependency injection in Drupal 7 (parameters)

cruisehunter_config_yaml.yaml

# CruiseHunter Config Yaml.
parameters:
    agency:   NULL
services:
    cruise_hunter_fetcher:
        class: CruiseHunter\CruiseHunterFetcher
        arguments:
            # Agency from which we will fetch the information
            - "@agency"

cruisehunter_namespace_register.module

<?php
/**
* Register a name class in Drupal
 * Implements hook_namespace_register().
 */
function cruisehunter_namespace_register() {
  // Structure array('<namespace>' => '<path>');
  return array(
    'CruiseHunter' => __DIR__ . '/lib',
  );
}

CruiseHunterFetcher.php

<?php
/**
 * Created by PhpStorm.
 * User: Alex Moreno
 * Date: 16/03/2014
 * Time: 16:19
 */

namespace CruiseHunter;

/**
 * Class CruiseHunterFetcher
 *
 * @package CruiseHunter
 */
class CruiseHunterFetcher {

  // List of Cruises in that object.
  protected $listOfCruises;

  /**
   * Execute robot to fetch the list of cruises from a given url.
   *
   * @param $url
   *  URL from which start the crawl.
   *
   * @return array
   *  Array with the list of cruises.
   */
  public function fetchListofCruises($url) {

    $this->listOfCruises = array();
  }

  /**
   * Return the list of cruises.
   *
   * @return array
   *   list of cruises in that object.
   */
  public function getListCruises() {

    return $this->listOfCruises;
  }

  /**
   *	Function to find cruise dates in an array or urls.
   *
   *	@urls
   */
  public function find_prices($urls) {

  }

  /**
   * Normalize string
   *
   * @param $string_to_normalize
   *   Normalized string $string_normalized
   *
   * @return mixed
   */
  public function normalize($string_to_normalize){

    return str_replace("€","",$string_to_normalize);

  }

}

fetch_cruises.module

<?php
/**
 * Example function to fetch cruises from site agencies.
 *
 */
function fetch_cruises() {

  try {
    global $_drupal_symfony_di_container;

    if (isset($_drupal_symfony_di_container)) {
      $service_manager = $_drupal_symfony_di_container->get('cruise_hunter_fetcher');
      $cruises = $service_manager->fetchListofCruises();

    }
  }
  catch(Exception $exp) {
    watchdog_exception('cruise_hunter', $exp);
  }
  
  return $cruises;
}

hook_symfony_yaml_config.module

<?php
/**
 * Implements hook_symfony_yaml_config().
 */
function cruisehunter_symfony_yaml_config() {
  // Return the path of the Yaml config files.
  // Structure array('<filename>' => '<file_path>');
  return array(
    'config.yaml' => drupal_get_path('module', 'cruisehunter') . '/config/yaml',
  );
}

hook_symfony_yaml_config_params.module

<?php
/**
 * Implements hook_symfony_yaml_config_params().
 */
function cruisehunter_symfony_yaml_config_params($container_builder) {
  // Param array to compile.
  $param_array = array();

  if ($container_builder instanceof ContainerBuilder) {
    // Generic Web Service Settings.
    $proxy_host = variable_get(WEBSERVICE_PROXY_HOST, NULL);
    $proxy_host = variable_get(WEBSERVICE_PROXY_PORT, NULL);

    // Add the proxy host and the port.
    if (isset($proxy_host) && isset($proxy_port)) {
      // Set proxy for wsdl client.
      $wsdl_pfw_options['WEBSERVICE_PROXY_HOST'] = $proxy_host;
      $wsdl_pfw_options['WEBSERVICE_PROXY_PORT'] = $proxy_port;
    }

  }

  return $param_array;
}