Mongoose autoReconnect option

Plucked from http://bites.goodeggs.com/posts/reconnecting-to-mongodb-when-mongoose-connect-fails-at-startup/

This worked for me:

var mongoose = require('mongoose')
var mongoUrl = "mongodb://localhost:27017/test"

var connectWithRetry = function() {
  return mongoose.connect(mongoUrl, function(err) {
    if (err) {
      console.error('Failed to connect to mongo on startup - retrying in 5 sec', err);
      setTimeout(connectWithRetry, 5000);
    }
  });
};
connectWithRetry();

I had the same question as you, and robertklep's solution didn't work for me either. I found when MongoDB service is stopped, an error event is triggered, but the connection.readyState is still 1 (connected). That may be why it didn't auto reconnect.

This is what I have now:

  var db = mongoose.connection;

  db.on('connecting', function() {
    console.log('connecting to MongoDB...');
  });

  db.on('error', function(error) {
    console.error('Error in MongoDb connection: ' + error);
    mongoose.disconnect();
  });
  db.on('connected', function() {
    console.log('MongoDB connected!');
  });
  db.once('open', function() {
    console.log('MongoDB connection opened!');
  });
  db.on('reconnected', function () {
    console.log('MongoDB reconnected!');
  });
  db.on('disconnected', function() {
    console.log('MongoDB disconnected!');
    mongoose.connect(dbURI, {server:{auto_reconnect:true}});
  });
  mongoose.connect(dbURI, {server:{auto_reconnect:true}});

Just for the sake of posterity, as most of these answers are old, you should not need to deal with this issue any more, as it is now baked into the nodejs mongodb driver. To quote kdmon:

...reconnecting is now baked into mongoose and enabled by default. But it might be useful to know that Mongoose by default will only try reconnecting for 30s and then give up. Set the server.reconnectTries option to increase the number of times mongoose will try to reconnect. For example, you can tell mongoose to never stop trying to reconnect like this:

mongoose.connect(uri, { server: { reconnectTries: Number.MAX_VALUE } });

See connection docs and server options defaults for details

Recently, I investigate the auto-reconnect with MongoDB var Mongoose. There is one issue here, when invoking mongoose.connect within disconnected event handler, it will trigger infinite loop. Why the SIGINT signal is blocked when mongoose auto reconnect.

One work around solution could be that the mongoose.connect() only be called when there is no connection with MongoDB before. The auto_reconnect flag could make mongoose reconnect with MongoDB automatically. Here are code snippets.

var mongoose = require('mongoose');

var isConnectedBefore = false;
var connect = function() {
    mongoose.connect('mongodb://localhost/' + + 'test_dev', {server: { auto_reconnect: true }});
};
connect();

mongoose.connection.on('error', function() {
    console.log('Could not connect to MongoDB');
});

mongoose.connection.on('disconnected', function(){
    console.log('Lost MongoDB connection...');
    if (!isConnectedBefore)
        connect();
});
mongoose.connection.on('connected', function() {
    isConnectedBefore = true;
    console.log('Connection established to MongoDB');
});

mongoose.connection.on('reconnected', function() {
    console.log('Reconnected to MongoDB');
});

// Close the Mongoose connection, when receiving SIGINT
process.on('SIGINT', function() {
    mongoose.connection.close(function () {
        console.log('Force to close the MongoDB conection');
        process.exit(0);
    });
});