Multi-environment wp-config

wp-config.php

<?php

// Define Environments - may be a string or array of options for an environment
$environments = array(
  'local'       => 'localhost',
//   'staging'     => 'staging-env',
);

// Get Server name
$server_name = $_SERVER['SERVER_NAME'];

foreach($environments AS $key => $env){
  if(is_array($env)){
    foreach ($env as $option){
      if(stristr($server_name, $option)){
        define('ENVIRONMENT', $key);
        break 2;
      }
    }
  } else {
    if(stristr($server_name, $env)){
      define('ENVIRONMENT', $key);
      break;
    }
  }
}

// If no environment is set default to production
if(!defined('ENVIRONMENT')) define('ENVIRONMENT', 'production');

// Define different DB connection details depending on environment
switch(ENVIRONMENT) {

  case 'local':

    define('DB_NAME', 'database_name_here');
    define('DB_USER', 'username_here');
    define('DB_PASSWORD', 'password_here');
    define('DB_HOST', 'localhost');
    define('WP_DEBUG', true);

    define('WP_SITEURL', 'http://site-url-here/');
    define('WP_HOME', 'http://site-url-here/');

    break;

  case 'staging':

    define('DB_NAME', 'database_name_here');
    define('DB_USER', 'username_here');
    define('DB_PASSWORD', 'password_here');
    define('DB_HOST', 'localhost');

    define('WP_SITEURL', 'http://site-url-here/');
    define('WP_HOME', 'http://site-url-here/');

    break;

}

// If database isn't defined then it will be defined here.
// Put the details for your production environment in here.
if(!defined('DB_NAME'))
  define('DB_NAME', 'database_name_here');

if(!defined('DB_USER'))
  define('DB_USER', 'username_here');

if(!defined('DB_PASSWORD'))
  define('DB_PASSWORD', 'password_here');

if(!defined('DB_HOST'))
  define('DB_HOST', 'localhost');

if(!defined('DB_CHARSET'))
  define('DB_CHARSET', 'utf8');

if(!defined('DB_COLLATE'))
  define('DB_COLLATE', '');


/**#@+
 * Authentication Unique Keys and Salts.
 *
 * Change these to different unique phrases!
 * You can generate these using the {@link https://api.wordpress.org/secret-key/1.1/salt/ WordPress.org secret-key service}
 * You can change these at any point in time to invalidate all existing cookies. This will force all users to have to log in again.
 *
 * @since 2.6.0
 */

if(!defined('AUTH_KEY'))
  define('AUTH_KEY', '');

if(!defined('SECURE_AUTH_KEY'))
  define('SECURE_AUTH_KEY', '');

if(!defined('LOGGED_IN_KEY'))
  define('LOGGED_IN_KEY', '');

if(!defined('NONCE_KEY'))
  define('NONCE_KEY', '');

if(!defined('AUTH_SALT'))
  define('AUTH_SALT', '');

if(!defined('SECURE_AUTH_SALT'))
  define('SECURE_AUTH_SALT', '');

if(!defined('LOGGED_IN_SALT'))
  define('LOGGED_IN_SALT', '');

if(!defined('NONCE_SALT'))
  define('NONCE_SALT', '');

/**#@-*/

/**
 * WordPress Database Table prefix.
 *
 * You can have multiple installations in one database if you give each a unique
 * prefix. Only numbers, letters, and underscores please!
 */
if(!isset($table_prefix)) $table_prefix  = 'wp_';

/**
 * WordPress Localized Language, defaults to English.
 *
 * Change this to localize WordPress. A corresponding MO file for the chosen
 * language must be installed to wp-content/languages. For example, install
 * de_DE.mo to wp-content/languages and set WPLANG to 'de_DE' to enable German
 * language support.
 */
if(!defined('WPLANG'))
  define('WPLANG', '');

/**
 * For developers: WordPress debugging mode.
 *
 * Change this to true to enable the display of notices during development.
 * It is strongly recommended that plugin and theme developers use WP_DEBUG
 * in their development environments.
 */
if(!defined('WP_DEBUG'))
  define('WP_DEBUG', false);

/* That's all, stop editing! Happy blogging. */

/** Absolute path to the WordPress directory. */
if ( !defined('ABSPATH') )
  define('ABSPATH', dirname(__FILE__) . '/');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');