Reliably reconnect to MongoDB

Question

UPDATE: I am using the 2.1 version on the driver, against 3.2

I have a node application that uses MongoDB. The problem I have is that if the MongoDB

Answer 1

package.json: "mongodb": "3.1.3"

Reconnect existing connections

To fine-tune the reconnect configuration for pre-established connections, you can modify the reconnectTries/reconnectInterval options (default values and further documentation here).

Reconnect initial connection

For the initial connection, the mongo client does not reconnect if it encounters an error (see below). I believe it should, but in the meantime, I've created the following workaround using the promise-retry library (which uses an exponential backoff strategy).

const promiseRetry = require('promise-retry')
const MongoClient = require('mongodb').MongoClient

const options = {
  useNewUrlParser: true,
  reconnectTries: 60,
  reconnectInterval: 1000,
  poolSize: 10,
  bufferMaxEntries: 0
}

const promiseRetryOptions = {
  retries: options.reconnectTries,
  factor: 1.5,
  minTimeout: options.reconnectInterval,
  maxTimeout: 5000
}

const connect = (url) => {
  return promiseRetry((retry, number) => {
    console.log(`MongoClient connecting to ${url} - retry number: ${number}`)
    return MongoClient.connect(url, options).catch(retry)
  }, promiseRetryOptions)
}

module.exports = { connect }

Mongo Initial Connect Error: failed to connect to server [db:27017] on first connect