monkeytype/backend/init/mongodb.js

const { MongoClient } = require("mongodb");

let mongoClient;

module.exports = {
  async connectDB() {
    let options = {
      useNewUrlParser: true,
      useUnifiedTopology: true,
      connectTimeoutMS: 2000,
      serverSelectionTimeoutMS: 2000,
    };

    if (process.env.DB_USERNAME && process.env.DB_PASSWORD) {
      options.auth = {
        username: process.env.DB_USERNAME,
        password: process.env.DB_PASSWORD,
      };
    }

    if (process.env.DB_AUTH_MECHANISM) {
      options.authMechanism = process.env.DB_AUTH_MECHANISM;
    }

    if (process.env.DB_AUTH_SOURCE) {
      options.authSource = process.env.DB_AUTH_SOURCE;
    }

    return MongoClient.connect(process.env.DB_URI, options)
      .then((client) => {
        mongoClient = client;
      })
      .catch((e) => {
        console.error(e.message);
        console.error("FAILED TO CONNECT TO DATABASE. EXITING...");
        process.exit(1);
      });
  },
  mongoDB() {
    return mongoClient.db(process.env.DB_NAME);
  },
};