configuration.php

<?php

class Config
{
    public $database_host = '127.0.0.1';
    public $database_port = 3306;
    public $database_name = 'response_map';
    public $database_user = 'rmap_user';
    public $database_pass = '';
    public $adminpassword = '19VZ7mDyYsHWs9iU3AWm';
    public $google_key = '';
    public $key_secret = '{}';
    public $instructor_roles = '["Instructor", "Administrator", "ContentDeveloper"]';

    // environment variables map with Config properties
    private $envs = array(
        'OPENSHIFT_MYSQL_DB_HOST' => 'database_host',
        'OPENSHIFT_MYSQL_DB_PORT' => 'database_port',
        'OPENSHIFT_APP_NAME' => 'database_name',
        'OPENSHIFT_MYSQL_DB_USERNAME' => 'database_user',
        'OPENSHIFT_MYSQL_DB_PASSWORD' => 'database_pass',
        'DB_HOST' => 'database_host',
        'DB_PORT' => 'database_port',
        'DB_NAME' => 'database_name',
        'DB_USERNAME' => 'database_user',
        'DB_PASSWORD' => 'database_pass',
        'ADMIN_PASSWORD' => 'adminpassword',
        'GOOGLE_KEY' => 'google_key',
        'OAUTH_CONSUMER' => 'key_secret',
        'INSTRUCTOR_ROLES' => 'instructor_roles',
    );

    public function __construct()
    {
        // include config.php if exists
        include('config.php');
        foreach ($this->envs as $k => $v) {
            $value = getenv($k);
            // if environment variable is set
            if ($value !== false) {
                $this->$v = $value;
                // if variable is set in config.php
            } else if (isset($$v)) {
                $this->$v = $$v;
            }
        }
    }
}

// initialize the configuration
$config = new Config();

// Establish a connection to the database
$conn = mysqli_connect($config->database_host, $config->database_user, $config->database_pass, $config->database_name, $config->database_port);
mysqli_set_charset($conn, 'utf8');