Heroku + mongoose connection error: no primary server found in set - node.js

Question

I have a mongodb replica set on mongolab.
I'm using nodejs + mongoose. When I'm trying to connect from my local machine everything goes ok.
But after deployment to heroku something wrong happens and mongoose got strange error:
[Error: no primary server found in set]
Here some code (server.js):
async.series([
function(callback){
console.log('DB Connection: ' + siteConf.mongo_url);
mongoose.connect(siteConf.mongo_url, siteConf.mongo_options, callback);
},
function(callback){
http.createServer(app).listen(siteConf.port, callback);
}
],
function(err, results){
if (err) {
console.log(err);
}
console.log('Running in ' + (process.env.NODE_ENV || 'development') + ' mode # ' + siteConf.uri);
}
);
This url I'm using as connection string:
mongodb://username:password#someid-a0.mongolab.com:39897/pm_prod,mongodb://someid-a1.mongolab.com:39897
The main thing I can't understand is: what is the differences between my maching and heroku cloud hosting.
I already tried to remove node_modules and npm install them to be sure that I have same versions as on heroku. (Because heroku do this on each deploy).
Thanks, and sorry for my bad english

Answer 1

This may be a URI problem. The format for DB URIs is:
mongodb://<user>:<pass>#host:port,host:port,...,host:port/db_name
That means that
mongodb://username:password#someid-a0.mongolab.com:39897/pm_prod,mongodb://someid-a1.mongolab.com:39897
should be:
mongodb://username:password#someid-a0.mongolab.com:39897,someid-a1.mongolab.com:39897/pm_prod
It's also worth noting for others: If you are using Heroku's MongoLab add-on, your URI is available as an environment variable at process.env.MONGOLAB_URI, so you don't have to place the URI in your code.
This could also be related to a running question about connectivity between Heroku and Mongo. See https://github.com/jcottr/temps-mort, which references two tickets for the Node Mongo driver:
https://jira.mongodb.org/browse/NODE-4
https://jira.mongodb.org/browse/NODE-5