Symfony2 configuration for Engine Yard environment variables.

config.yml

# app/config/config.yml

imports:
    - { resource: parameters.yml }
    - { resource: engineyard.php }
    - { resource: security.yml }

...

engineyard.php

<?php
// app/config/engineyard.php

if ('prod' !== $container->getParameter('kernel.environment')) {
    return;
}

// Change this to the path to your project config directory.
$configPath = '/data/my_project/shared/config';

$eyParams = array(
    'DB_HOST'    => 'database_host',
    'DB_NAME'    => 'database_name',
    'DB_USER'    => 'database_user',
    'DB_PASS'    => 'database_password',
);

if (!isset($_SERVER['DB_HOST'])) {
    $dbConfig = $configPath . '/database.yml';
    engineyard_parse_db($dbConfig, $container);
} else {
    engineyard_parse_server($eyParams, $container);
}

$envCustom = $configPath . '/env.custom';
engineyard_parse_env($envCustom, $container);

// ----------------------------------------------------------

function engineyard_parse_server($params, $container)
{
    foreach ($params as $key => $value) {
        if (isset($_SERVER[$key])) {
            $container->setParameter($value, $_SERVER[$key]);
        }
    }
}

function engineyard_parse_env($filename, $container)
{
    $params = parse_ini_file($filename);

    if (false === $params) {
        engineyard_bad_config($filename);
    }

    foreach ($params['env'] as $key => $value) {
        $container->setParameter(strtolower($key), $value);
    }
}

function engineyard_parse_db($filename, $container)
{
    $yaml     = new Symfony\Component\Yaml\Yaml();
    $contents = file_get_contents($filename);

    if (false === $contents) {
        engineyard_bad_config($filename);
    }

    try {
        $params = $yaml->parse($contents);
    } catch (\Exception $badYaml) {
        engineyard_bad_config($filename);
    }

    $env  = $container->getParameter('kernel.environment');
    if (!array_key_exists($env, $params)) {
        return;
    }

    $data = $params[$env];

    $names = array(
        'database' => 'database_name',
        'username' => 'database_user',
        'password' => 'database_password',
        'host'     => 'database_host',
    );

    foreach ($names as $key => $param) {
        if (array_key_exists($key, $data)) {
            $container->setParameter($param, $data[$key]);
        }
    }
}

function engineyard_bad_config($filename)
{
    throw new \RuntimeException('Could not parse config ' . $filename);
}