{ useUnifiedTopology: true } leads to MongoDB connection error: MongoTimeoutError: Server selection timed out after 30000 ms

Do you want to request a feature or report a bug?

A bug.

What is the current behavior?

After updating to Mongoose 5.7.1, the following warning appeared:

(node:41563) 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.
    at parseFn (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/node_modules/mongodb/lib/operations/connect.js:312:5)
    at parseConnectionString (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/node_modules/mongodb/lib/core/uri_parser.js:628:3)
    at connect (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/node_modules/mongodb/lib/operations/connect.js:266:3)
    at ConnectOperation.execute (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/node_modules/mongodb/lib/operations/connect.js:191:5)
    at executeOperation (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/node_modules/mongodb/lib/operations/execute_operation.js:83:26)
    at MongoClient.connect (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/node_modules/mongodb/lib/mongo_client.js:216:10)
    at Promise (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/lib/connection.js:632:12)
    at Promise._execute (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/bluebird/js/release/debuggability.js:313:9)
    at Promise._resolveFromExecutor (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/bluebird/js/release/promise.js:488:18)
    at new Promise (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/bluebird/js/release/promise.js:79:10)
    at NativeConnection.Connection.openUri (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/lib/connection.js:629:19)
    at Mongoose.connect (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/mongoose/lib/index.js:327:15)
    at Object.connect (/Users/tschaffter/dev/PHCCollaborationPortal/server/app.js:17:44)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Module._compile (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/pirates/lib/index.js:99:24)
    at Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Object.newLoader [as .js] (/Users/tschaffter/dev/PHCCollaborationPortal/node_modules/pirates/lib/index.js:104:7)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Object.<anonymous> (/Users/tschaffter/dev/PHCCollaborationPortal/server/index.js:12:28)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)

I added useUnifiedTopology: true to my mongoose config object as suggested by the message, even though I’m not using MongoDB replica set or sharded cluster. Here is how I configure and connect using mongoose:

        options: {
            // https://mongoosejs.com/docs/deprecations.html
            useNewUrlParser: true,
            useFindAndModify: false,
            useCreateIndex: true,
            useUnifiedTopology: true,
            reconnectTries: 30,
            reconnectInterval: 500, // in ms
        }
    },

and here is where I used this mongo.options object:

// Connect to MongoDB
const mongooseConnectionPromise = mongoose.connect(config.mongo.uri, config.mongo.options);
mongoose.connection.on('error', err => {
    console.error(`MongoDB connection error: ${err}`);
    process.exit(-1); // eslint-disable-line no-process-exit
});

The warning is gone but the issue is that mongoose is now no longer able to connect:

MongoDB connection error: MongoTimeoutError: Server selection timed out after 30000 ms
[nodemon] app crashed - waiting for file changes before starting...

Here is how I run MongoDB using docker during development:

docker run -p ${MONGO_PORT}:${MONGO_PORT} --name mongo -d mongo

If the current behavior is a bug, please provide the steps to reproduce.

See above

What is the expected behavior?

Mongoose should remove the deprecation warning and run fine when using useUnifiedTopology: true as mongoose suggests.

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that “latest” is not a version.

Node: v10.16.2 Mongoose: 5.7.1 (latest) MongoDB: db version v4.2.0

Related issues:

• https://github.com/Automattic/mongoose/issues/8156
• https://github.com/Automattic/mongoose/issues/8169

[mbroadst]

Hi! My name is Matt and I’m on the drivers team at MongoDB. We’re very sorry for the outages y’all have been facing, and I wanted to give a little update on the issue:

We’re in the process of trying to phase out our legacy topology types which has turned out to be a very surgical process. Phasing out these types will help greatly reduce the maintenance burden of the driver, and our hope is that means a more stable and efficient driver for our users. In particular, while introducing the “Unified Topology” we did not also introduce the rewrite of the connection pool in an effort to reduce the potential for error. It turns out the connection pool was more tightly coupled to the topology types than we anticipated and as a result we experienced some regressions, particularly around server monitoring.

This morning I pushed a v3.3.4-rc0 of the driver which should address the issues you have been facing. We would be extremely grateful if you could try this version out and report back with your experience. I have left comments on each of the existing tickets related to this issue on NODE-2267, but please feel free to open additional issues there if you experience them.

[crobinson42]

This is an issue with replica set MongoDB servers and a solution is being worked on here by MongoDB engineers

https://jira.mongodb.org/browse/NODE-2267

@vkarpov15 can probably close this issue because it has nothing to do with Mongoose.