Feature for declaring the Hosts for reading from a URI (file, url).

Mage/Config.php

@@ -49,7 +49,14 @@ class Mage_Config
         $hosts = array();
         
         if (isset($config['hosts'])) {
+            if (is_array($config['hosts'])) {
                 $hosts = (array) $config['hosts'];                
+            } else if (is_string($config['hosts'])) {
+                $fileContent = fopen($config['hosts'], 'r');
+                while (($host = fgets($fileContent)) == true) {
+                    $hosts[] = trim($host);
+                }
+            }
         }
         
         return $hosts;

docs/example-config/.mage/config/environment/staging.yaml

@@ -3,8 +3,7 @@ deployment:
   user: stg_user
   from: ./
   to: /var/www/vhosts/example.com/staging
-hosts:
-  - staging.example.com
+hosts: /tmp/current-staging-hosts.txt
 tasks:
   pre-deploy:
     - scm/update