Drush aliases: scrub "remote host" key for cross-environment use

drush-alias-remote-host-check.php

<?php

/**
 * @file
 * Example drush alias file for multihost use.
 */

// Alias settings common to all.
$aliases['base'] = array(
  'root'         => '/var/www/docroot',
  'remote-user'  => 'georgepburdell',
  'path-aliases' => array(
    '%files' => 'sites/default/files',
    '%dump'  => '/tmp/dump.sql',
  ),
);

// We explicitly include the "remote-host" key for each alias below. This means
// that the aliases won't work when logged in to the same box. E.g. @dev fails
// while logged into the dev server. So, at the end, we determine the current
// server and remove "remote-host" from all local aliases.
//
// Dev site.
$aliases['dev'] = array(
  'parent'      => '@example.base',
  'remote-host' => 'dev.example.com',
  'uri'         => 'dev.example.com',
);

// Alias entry for a "home directory" site hosted on the dev server. Note the
// parent is @dev and not @base.
$aliases['georgepburdell'] = array(
  'parent' => '@example.dev',
  'root'   => '/home/georgepburdell/public_html',
  'uri'    => 'georgepburdell.dev.example.com',
);

// Staging site.
$aliases['stage'] = array(
  'parent'      => '@example.base',
  'remote-host' => 'stage.example.com',
  'uri'         => 'stage.example.com',
);

// Production site.
$aliases['prod'] = array(
  'parent'      => '@example.base',
  'remote-host' => 'www.example.com',
  'uri'         => 'www.example.com',
);

// TLDR; MAGIC STARTS HERE.
//
// Remove "remote-host" from entries that correspond with the current server.
// This allows us to use the same alias file in all environments.
$ip = gethostbyname(php_uname('n'));
foreach ($aliases as &$alias) {
  if (empty($alias['remote-host'])) {
    continue;
  }
  if (gethostbyname($alias['remote-host']) == $ip) {
    unset($alias['remote-host']);
  }
}