Error establishing a database connection with WordPress on CloudSQL

Question

I cannot, for the life of me, connect my WordPress Google App Engine deployment to the CloudSQL instance that I have.

app.yaml

application: dark-gateway-XXX
version: wp
runtime: php
api_version: 1

handlers:
- url: /(.*\.(htm|html|css|js))$
static_files: wordpress/\1
upload: wordpress/.*\.(htm|html|css|js)$
application_readable: true

- url: /wp-content/(.*\.(ico|jpg|png|gif))$
static_files: wordpress/wp-content/\1
upload: wordpress/wp-content/.*\.(ico|jpg|png|gif)$
application_readable: true

- url: /(.*\.(ico|jpg|png|gif))$
static_files: wordpress/\1
upload: wordpress/.*\.(ico|jpg|png|gif)$

- url: /wp-admin/(.+)
script: wordpress/wp-admin/\1
secure: always

- url: /wp-admin/
script: wordpress/wp-admin/index.php
secure: always

- url: /wp-login.php
script: wordpress/wp-login.php
secure: always

- url: /wp-cron.php
script: wordpress/wp-cron.php
login: admin

- url: /xmlrpc.php
script: wordpress/xmlrpc.php

- url: /wp-(.+).php
script: wordpress/wp-\1.php

- url: /(.+)?/?
script: wordpress/index.php`

wp-config

<?php
/**
 * The base configurations of the WordPress.
 *
 * This file has the following configurations: MySQL settings, Table Prefix,
 * Secret Keys, WordPress Language, and ABSPATH. You can find more information
 * by visiting {@link http://codex.wordpress.org/Editing_wp-config.php Editing
 * wp-config.php} Codex page. You can get the MySQL settings from your web host.
 *
 * This file is used by the wp-config.php creation script during the
 * installation. You don't have to use the web site, you can just copy this file
 * to "wp-config.php" and fill in the values.
 *
 * @package WordPress
 */

// Required for batcache use
define('WP_CACHE', true);

// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define('DB_NAME', 'production_db');

/** MySQL database username */
define('DB_USER', 'root');

if (isset($_SERVER['SERVER_SOFTWARE']) && strpos($_SERVER['SERVER_SOFTWARE'],'Google App Engine') !== false) {
/** Live environment Cloud SQL login and SITE_URL info */
    define('DB_HOST', ':/cloudsql/dark-gateway-XXX:production');
define('DB_USER', 'root');
define('DB_PASSWORD', 'XXXX');
} else {
/** Local environment MySQL login info */
    define('DB_HOST', '127.0.0.1');
define('DB_USER', 'root');
define('DB_PASSWORD', 'password');
}

// Determine HTTP or HTTPS, then set WP_SITEURL and WP_HOME
if (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443)
{
$protocol_to_use = 'https://';
} else {
    $protocol_to_use = 'http://';
}
define( 'WP_SITEURL', $protocol_to_use . $_SERVER['HTTP_HOST']);
define( 'WP_HOME', $protocol_to_use . $_SERVER['HTTP_HOST']);

/** Database Charset to use in creating database tables. */
define('DB_CHARSET', 'utf8');

/** The Database Collate type. Don't change this if in doubt. */
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
 */
define('AUTH_KEY',         'put your unique phrase here');
define('SECURE_AUTH_KEY',  'put your unique phrase here');
define('LOGGED_IN_KEY',    'put your unique phrase here');
define('NONCE_KEY',        'put your unique phrase here');
define('AUTH_SALT',        'put your unique phrase here');
define('SECURE_AUTH_SALT', 'put your unique phrase here');
define('LOGGED_IN_SALT',   'put your unique phrase here');
define('NONCE_SALT',       'put your unique phrase here');

/**#@-*/

/**
 * 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!
 */
$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.
 */
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.
 */
define('WP_DEBUG', false);

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

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

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

// configures batcache
$batcache = [
  'seconds'=>0,
  'max_age'=>30*60, // 30 minutes
  'debug'=>false
];

I followed these instruction. The only thing I did different was to rename my DB. http://googlecloudplatform.github.io/appengine-php-wordpress-starter-project/

Any help would be appreciated as I cannot find this info anywhere.

Answer 1

When connecting to Cloud SQL from App Engine as root, you should not use a password, just an empty string:

define('DB_HOST', ':/cloudsql/dark-gateway-XXX:production');
define('DB_USER', 'root');
define('DB_PASSWORD', '');

https://developers.google.com/appengine/docs/php/cloud-sql/#PHP_Connect_to_your_database

The root password that you can set in the console only applies to external connections.

Answer 2

Your files look good so the next step is to verify settings at run time. In wp-config.php, before the define('DB_HOST',...) line, add a line to log execution, such as:

syslog(LOG_INFO, 'setting AppEngine Cloud SQL client parameters');

Sprinkle similar syslog calls in the other project files not shown here, before and after expected database access. Include values of variables where possible. View the output in the Logs part of the AppEngine Dashboard. The results should enable you to gradually close in on the actual fault.