exposed redis' "connect" method, so socket.io can call it from outside database/redis.js, fixed NodeBB requiring Redis as a socket.io store. It will now go back to using in-memory store per process, if no redis config is found in the NodeBB configuration. re: #2097

src/database/redis.js

@@ -47,26 +47,7 @@
 			process.exit();
 		}
 
-		var redis_socket_or_host = nconf.get('redis:host');
-
-		if (redis_socket_or_host && redis_socket_or_host.indexOf('/')>=0) {
-			/* If redis.host contains a path name character, use the unix dom sock connection. ie, /tmp/redis.sock */
-			redisClient = redis.createClient(nconf.get('redis:host'));
-		} else {
-			/* Else, connect over tcp/ip */
-			redisClient = redis.createClient(nconf.get('redis:port'), nconf.get('redis:host'));
-		}
-
-		if (nconf.get('redis:password')) {
-			redisClient.auth(nconf.get('redis:password'));
-		} else {
-			winston.warn('You have no redis password setup!');
-		}
-
-		redisClient.on('error', function (err) {
-			winston.error(err.stack);
-			process.exit(1);
-		});
+		redisClient = module.connect();
 
 		module.client = redisClient;
 
@@ -104,6 +85,34 @@
 		}
 	};
 
+	module.connect = function() {
+		var redis_socket_or_host = nconf.get('redis:host'),
+			cxn;
+
+		if (!redis) redis = require('redis');
+
+		if (redis_socket_or_host && redis_socket_or_host.indexOf('/') >= 0) {
+			/* If redis.host contains a path name character, use the unix dom sock connection. ie, /tmp/redis.sock */
+			cxn = redis.createClient(nconf.get('redis:host'));
+		} else {
+			/* Else, connect over tcp/ip */
+			cxn = redis.createClient(nconf.get('redis:port'), nconf.get('redis:host'));
+		}
+
+		if (nconf.get('redis:password')) {
+			cxn.auth(nconf.get('redis:password'));
+		} else {
+			winston.warn('You have no redis password setup!');
+		}
+
+		cxn.on('error', function (err) {
+			winston.error(err.stack);
+			process.exit(1);
+		});
+
+		return cxn;
+	};
+
 	module.close = function() {
 		redisClient.quit();
 	};

src/socket.io/index.js

@@ -66,23 +66,32 @@ function onUserDisconnect(uid, socketid, socketCount) {
 }
 
 Sockets.init = function(server) {
-	 var RedisStore = require('socket.io/lib/stores/redis'),
-		redis = require('redis'),
-		pub = redis.createClient(),
-		sub = redis.createClient(),
-		client = redis.createClient();
-
-	io = socketioWildcard(SocketIO).listen(server, {
+	// Default socket.io config
+	var config = {
 			log: false,
 			transports: ['websocket', 'xhr-polling', 'jsonp-polling', 'flashsocket'],
 			'browser client minification': true,
-		resource: nconf.get('relative_path') + '/socket.io',
-		'store' : new RedisStore({
+			resource: nconf.get('relative_path') + '/socket.io'
+		};
+
+	// If a redis server is configured, use it as a socket.io store, otherwise, fall back to in-memory store
+	if (nconf.get('redis')) {
+		var RedisStore = require('socket.io/lib/stores/redis'),
+			database = require('../database/redis'),
+			pub = database.connect(),
+			sub = database.connect(),
+			client = database.connect();
+
+		config.store = new RedisStore({
 			redisPub : pub,
 			redisSub : sub,
 			redisClient : client
-		}),
 		});
+	} else if (nconf.get('cluster')) {
+		winston.warn('[socket.io] Clustering detected, you are advised to configure Redis as a websocket store.')
+	}
+
+	io = socketioWildcard(SocketIO).listen(server, config);
 
 	Sockets.server = io;