CODEWITHSUNDEEP
node.jsmongodbmongooseprometheus
korolar
korolar

Reputation: 1535

How to monitor Mongoose connection pool

There's probably an obvious answer to this, but I can't seem to find it. I'm using Mongoose in my node app to connect to a MongoDB cluster. Is there any way to monitor the state of the client-side connection pool that Mongoose uses? Like a number of connection in the pool, number of connections currently checked-out from the pool, the rate at which connections are checked-out, etc? Bonus points if there's already a well established solution of exporting these metrics in Prometheus format.

Upvotes: 2

Views: 947

Answers (2)

phoenixstudio
phoenixstudio

Reputation: 2618

If you are looking to get only stats for example via an API you can use this

 mongoose.connection.db?.command({ serverStatus: 1})
    .then(results => console.log("connections", results.connections))
    .catch(error => console.error("command serverStatus error: ", error));

As results you will get something like this (same as what you get when running db.serverStatus().connections in mongosh):

connections {
     current: 39,
     available: 51161,
     totalCreated: 740,
     rejected: 0,
     active: 21,
     threaded: 39,
     exhaustIsMaster: 0,
     exhaustHello: 2,
     awaitingTopologyChanges: 5
 }

Upvotes: 0

divinelemon
divinelemon

Reputation: 2097

You can use the connection pool events. These events are triggered by specified pool-related events, such as connections, closures, and more.

Here’s a working example with the MongoDB module taken from the MongoDB official docs:

const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:31000,localhost:31001/?replicaSet=rs';
const client = new MongoClient(url);

client.on('connectionPoolCreated', event => console.dir(event));
client.on('connectionPoolClosed', event => console.dir(event));
client.on('connectionCreated', event => console.dir(event));
client.on('connectionReady', event => console.dir(event));
client.on('connectionClosed', event => console.dir(event));
client.on('connectionCheckOutStarted', event => console.dir(event));
client.on('connectionCheckOutFailed', event => console.dir(event));
client.on('connectionCheckedOut', event => console.dir(event));
client.on('connectionCheckedIn', event => console.dir(event));
client.on('connectionPoolCleared', event => console.dir(event));

client.connect((err, client) => {
  if (err) throw err;
});

However, if you want to do this in Mongoose, you can use connection.getClient() which returns the underlying mongodb client, bypassing the mongoose driver.

Method described in this GitHub issue

Upvotes: 3

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