db-credentials

#!/usr/bin/env php
<?php
// Can't use a namespace here yet because of this bug: https://bugs.php.net/bug.php?id=66566
//namespace Loadsys\CakePHPShellScripts\DbCredentials;

/**
 * Prints usage information and exits.
 *
 * @param string $script Typically set to basename($argv[0]) when the method is called.
 * @param int $exitCode The numeric exit code to return. 0 = success. >0 = failure.
 * @return void
 */
function usage($script = null, $exitCode = 0) {
	$script = $script ?: basename(__FILE__);
	$usage = <<<EOD

${script}
    Reads a Cake app's default database connection configuration and
    formats it for consumption by bash scripts or for inclusion in
    other PHP scripts. Useful for auto-logging-into the proper
    database for the Cake app from the command line, or for initiating
    a mysqldump backup.

    Depends on the availability of the ConsoleShell, and by extension
    the `psy/psysh` composer package.


Usage:
    bin/${script}

    This will print bash variable declarations to the console. To import
    these into another bash script, use `eval \$( bin/${script} )`,
    which will populate variables for DB_HOST, DB_PORT, DB_DATABASE,
    DB_LOGIN and DB_PASSWORD. See `db-login` for a usage pattern that
    preserves special char escaping for DB_PASS.

    This script can also detect when it has been `include()`d from
    another PHP script, and will return an object with properties set
    for any keys defined in [Datasources][default] in config/app.php.
    With this style, if ${script} runs into any trouble, it will return
    an \Exception, so check for that in your consuming script. You also
    need to wrap the call in output buffering to squash the shebang at
    the top of this file.

        <?php
        \$credentialsScript = "bin/db-credentials";
        if (!is_readable(\$credentialsScript)) {
            echo "!! DB credentials are not available. Aborting.";
            exit(3);
        }

        ob_start(); // Capture the shebang line from db-credentials.
        \$db = include(\$credentialsScript);
        ob_get_clean(); // Flush it.

        if (\$db instanceof \Exception) {
            echo \$db->getMessage();
            exit(4);
        }

        // Now safe to access \$db->host, \$db->username, etc.

EOD;

	echo $usage;
	exit($exitCode);
}


/**
 * Simulates a Cake 2 style DB_CONFIG class object.
 *
 * Obtains values from either the ConfigReadShell when available, or by
 * calling the ConsoleShell and loads them into the ::$default class
 * property of the instance.
 */
class DbConfig {

	/**
	 * Populate the object's properties with DB connection values.
	 *
	 * @return void
	 */
	public function __construct() {
		$injectedCode = 'echo serialize(\Cake\Datasource\ConnectionManager::config("default")) . PHP_EOL; exit;'; // This must be on a single line to work with the REPL.
		$cmd = "echo '{$injectedCode}' | "
			. escapeshellcmd("bin/cake Console -q");
		$response = [];
		$code = 0;
		exec($cmd, $response, $code);

		if (empty($response) || $code > 0) {
			throw new RuntimeException(
				'Unable to fetch Database config from ConsoleShell.'
			);
		}

		$unserialized = @unserialize(implode('', $response));
		if (empty($unserialized)) {
			throw new RuntimeException(
				'Unable to retrieve Datasources.default config from Configure.'
			);
		}

		foreach ($unserialized as $key => $val) {
			$this->{$key} = $val;
		}
	}

	/**
	 * Handle requests for properties that we didn't obtain from the Cake app.
	 *
	 * This will only ever get called when the "real" property doesn't exist,
	 * so all we have to do is return the empty string.
	 *
	 * @param string $name The name of the property being accessed.
	 * @return string Always the empty string: ''.
	 */
	public function __get($name) {
		return '';
	}
}


/**
 * Prints essential DB values to the console in bash variable declaration format.
 *
 * @param DbConfig $db A DbConfig instance with ::$default properties set.
 * @return void
 */
function printDbConfig($db) {
	echo <<<EOD
DB_HOST='{$db->host}'
DB_PORT='{$db->port}'
DB_DATABASE='{$db->database}'
DB_USERNAME='{$db->username}'
DB_PASSWORD='{$db->password}'
EOD;
}


/**
 * main() ===================================================================
 */

if (isset($argv[1]) && $argv[1] == '-h') {
	usage();
}

// Determine if this PHP file has been `include()`d from another PHP script.
$isIncluded = (count(get_included_files()) > 1);

// First try running the command line to fetch the configs.
try {
	$db = new DbConfig();
} catch (Exception $e) { // If that fails, either pass the exception to our parent, or print the error and exit.
	if($isIncluded) {
		return $e;
	} else {
		echo $e->getMessage();
		exit(2);
	}
}

if($isIncluded) { // Be friendly and return the $db object to them.
	return $db;
} else { // Otherwise print bash-compatible var declarations and exit.
	printDbConfig($db);
	exit(0);
}