AWS Dynamodb Session for SilverStirpe

_config.php

<?php
use Aws\DynamoDb\DynamoDbClient;
use Aws\DynamoDb\Session\SessionHandler;

// DISCLAIMER: untested and should just be used as guideline
// 
// Either fetches the required credentials from the ec2 server or requires to add them to a _ss_environment.php file
// AWS_REGION_NAME <- required
// AWS_DYNAMODB_SESSION_TABLE <- required
// AWS_SECRET_KEY
// AWS_DYNAMODB_SESSION_LIFETIME

$dynamoOptions = array('region' => AWS_REGION_NAME);

if(defined('AWS_ACCESS_KEY') && defined('AWS_SECRET_KEY')) {
	$dynamoOptions['key'] = AWS_ACCESS_KEY;
	$dynamoOptions['secret'] = AWS_SECRET_KEY;
} else {
	// cache credentials when IAM fetches the credentials from EC2 metadata service
	// this will use doctrine/cache (included via composer) to do the actual caching into the filesystem
	// http://docs.aws.amazon.com/aws-sdk-php/guide/latest/performance.html#cache-instance-profile-credentials
	$dynamoOptions['credentials.cache'] = true;
}

if(defined('AWS_DYNAMODB_SESSION_LIFETIME')) {
	$dynamoOptions['session_lifetime'] = AWS_DYNAMODB_SESSION_LIFETIME;
}

if(!isset($dynamoOptions['session_lifetime'])) {
	$timeout = Config::inst()->get('Session', 'timeout');
	if($timeout != null) {
		$dynamoOptions['session_lifetime'] = $timeout;
	}
}

$client = DynamoDbClient::factory($dynamoOptions);

$handler = SessionHandler::factory(array(
        'dynamodb_client' => $client,
        'table_name' => AWS_DYNAMODB_SESSION_TABLE
));

$handler->register();

// The garbage collection command below needs to be run at regular interval, see aws docs for it
// $handler->garbageCollect()