title: Mongoose connection to replica set
body: <p>I tried to connect to MongoDB replicaSet via mongoose. I used this <a href="http://mongoosejs.com/docs/connections.html" rel="noreferrer">link</a>.<br/>
  Configuration json:<br/></p>
  
  <pre><code>"mongoose": {
     "uri": "mongodb://localhost:27022/chat,localhost:27021,localhost:27020",
     "options": {
         "replset": { "rs_name": "rs0" },
         "server": {
             "poolSize": 3,
             "socketOptions": {
                 "keepAlive": 1
             }
         }
      }
  }
  </code></pre>
  
  <p>Mongoose connect:</p>
  
  <pre><code>var mongoose = require('mongoose');
  mongoose.connect(config.get('mongoose:uri'), config.get('mongoose:options'));
  </code></pre>
  
  <p>And after launching application i got exception:</p>
  
  <pre><code>Error: host must be specified [undefined]
  at new exports.ConnectionPool (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\mongodb\lib\mongodb\connection\connection_pool.js:18:11)
  at Server.connect (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\mongodb\lib\mongodb\connection\server.js:335:25)
  at Db.open (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\mongodb\lib\mongodb\db.js:264:23)
  at MongoStore._open_database (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\connect-mongo\lib\connect-mongo.js:174:15)
  at MongoStore._get_collection (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\connect-mongo\lib\connect-mongo.js:169:14)
  at MongoStore.get (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\connect-mongo\lib\connect-mongo.js:213:10)
  at Object.session [as handle] (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\connect\node_modules\express-session\index.js:215:11)
  at next (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\connect\lib\proto.js:194:15)
  at Object.module.exports [as handle] (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\middleware\resExtensions.js:21:2)
  at next (c:\Users\lor1an\Downloads\prj_chat-master\prj_chat-master\node_modules\connect\lib\proto.js:194:15)
  </code></pre>
  
  <p>Db: chat, primary server: localhost:27022.</p>
  
  <p>Also I tried remove two other servers (keeping only the primary one in config json) and I saw that it knows about the secondary servers (I used log). I think it's about mongodb meta-data. But when I shutdown primary one, it finished its work (no wonder), I need it so it can use the secondary one instead.<br/>
  Any ideas?</p>