diff --git a/composer.json b/composer.json
index 60094d5bd..9a86ebc2c 100644
--- a/composer.json
+++ b/composer.json
@@ -77,6 +77,12 @@
 		"npm-asset/textcomplete": "^0.18.2",
 		"npm-asset/typeahead.js": "^0.11.1"
 	},
+	"suggest": {
+		"ext-imagick": "For faster image processing",
+		"ext-redis": "To use Redis as a locking or caching provider",
+		"ext-pdo": "To use PDO as a database driver, has priority over mysqli unless database.disable_pdo is set",
+		"ext-mysqli": "To use mysqli as a databse driver"
+	},
 	"repositories": [
 		{
 			"type": "vcs",
diff --git a/src/Core/Cache/Type/RedisCache.php b/src/Core/Cache/Type/RedisCache.php
index be2a7ff08..a6ce7c44b 100644
--- a/src/Core/Cache/Type/RedisCache.php
+++ b/src/Core/Cache/Type/RedisCache.php
@@ -57,22 +57,27 @@ class RedisCache extends AbstractCache implements ICanCacheInMemory
 		$redis_host = $config->get('system', 'redis_host');
 		$redis_port = $config->get('system', 'redis_port');
 		$redis_pw   = $config->get('system', 'redis_password');
-		$redis_db   = $config->get('system', 'redis_db', 0);
+		$redis_db   = (int)$config->get('system', 'redis_db', 0);
 
 		try {
-
-			if (!empty($redis_port) && !@$this->redis->connect($redis_host, $redis_port)) {
-				throw new CachePersistenceException('Expected Redis server at ' . $redis_host . ':' . $redis_port . ' isn\'t available');
-			} else if (!@$this->redis->connect($redis_host)) {
-				throw new CachePersistenceException('Expected Redis server at ' . $redis_host . ' isn\'t available');
+			if (is_numeric($redis_port) && $redis_port > -1) {
+				$connection_string = $redis_host . ':' . $redis_port;
+				if (!@$this->redis->connect($redis_host, $redis_port)) {
+					throw new CachePersistenceException('Expected Redis server at ' . $connection_string . " isn't available");
+				}
+			} else {
+				$connection_string = $redis_host;
+				if (!@$this->redis->connect($redis_host)) {
+					throw new CachePersistenceException('Expected Redis server at ' . $connection_string . ' isn\'t available');
+				}
 			}
 
 			if (!empty($redis_pw) && !$this->redis->auth($redis_pw)) {
-				throw new CachePersistenceException('Cannot authenticate redis server at ' . $redis_host . ':' . $redis_port);
+				throw new CachePersistenceException('Cannot authenticate redis server at ' . $connection_string);
 			}
 
 			if ($redis_db !== 0 && !$this->redis->select($redis_db)) {
-				throw new CachePersistenceException('Cannot switch to redis db ' . $redis_db . ' at ' . $redis_host . ':' . $redis_port);
+				throw new CachePersistenceException('Cannot switch to redis db ' . $redis_db . ' at ' . $connection_string);
 			}
 		} catch (\RedisException $exception) {
 			throw new CachePersistenceException('Redis connection fails unexpectedly', $exception);
diff --git a/static/defaults.config.php b/static/defaults.config.php
index e8f44613c..6c9e2dd3c 100644
--- a/static/defaults.config.php
+++ b/static/defaults.config.php
@@ -543,11 +543,11 @@ return [
 		'pushpoll_frequency' => 3,
 
 		// redis_host (String)
-		// Host name of the redis daemon.
+		// Host name or the path to the Unix domain socket of the Redis daemon.
 		'redis_host' => '127.0.0.1',
 
-		// redis_port (String)
-		// Port number of the redis daemon.
+		// redis_port (Integer)
+		// Port number of the Redis daemon, should be -1 for unix domain socket
 		'redis_port' => 6379,
 
 		// redis_db (Integer)