Server Discovery And Monitoring engine is deprecated

Question

I am using Mongoose with my Node.js app and this is my configuration:

mongoose.connect(process.env.MONGO_URI, {
   useNewUrlParser: true,
   useUnifiedTopology: true,
   useCreateIndex: true,
   useFindAndModify: false
}).then(()=>{
    console.log(`connection to database established`)
}).catch(err=>{
    console.log(`db error ${err.message}`);
    process.exit(-1)
})

but in the console it still gives me the warning:

DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.

What is the problem? I was not using useUnifiedTopology before but now it shows up in the console. I added it to the config but it still gives me this warning, why? I do not even use MongoClient.

Edit

As Felipe Plets answered there was a problem in Mongoose and they fixed this bug in later versions. So you can solve problem by updating mongoose version.

Answer 1

Update

Mongoose 5.7.1 was release and seems to fix the issue, so setting up the useUnifiedTopology option work as expected.

mongoose.connect(mongoConnectionString, {useNewUrlParser: true, useUnifiedTopology: true});

Original answer

I was facing the same issue and decided to deep dive on Mongoose code: https://github.com/Automattic/mongoose/search?q=useUnifiedTopology&unscoped_q=useUnifiedTopology

Seems to be an option added on version 5.7 of Mongoose and not well documented yet. I could not even find it mentioned in the library history https://github.com/Automattic/mongoose/blob/master/History.md

According to a comment in the code:

• @param {Boolean} [options.useUnifiedTopology=false] False by default. Set to true to opt in to the MongoDB driver's replica set and sharded cluster monitoring engine.

There is also an issue on the project GitHub about this error: https://github.com/Automattic/mongoose/issues/8156

In my case I don't use Mongoose in a replica set or sharded cluster and though the option should be false. But if false it complains the setting should be true. Once is true it still don't work, probably because my database does not run on a replica set or sharded cluster.

I've downgraded to 5.6.13 and my project is back working fine. So the only option I see for now is to downgrade it and wait for the fix to update for a newer version.