Mongoose Connection Initializer

1 public initializeDbConnection(): void {
2
3    // Atomic DB Connection
4    const connectionOpts = {
5      useNewUrlParser: true,
6      server: { socketOptions: { keepAlive: 1, connectTimeoutMS: 30000 } },
7      replset: { socketOptions: { keepAlive: 1, connectTimeoutMS: 30000 } }
8    };
9    (<any>mongoose).Promise = bluebird;
10    this.db = mongoose.connection;
11    this.db.once('open', () => {
12      logService.log('debug', 'Database connection is open.');
13    });
14    this.db.on('error', (err) => {
15      logService.log('debug', 'Database connection error.', err);
16      if (err) throw err;
17      process.exit(1);
18    });
19    mongoose.connect(process.env.MONGODB_URI, connectionOpts)
20    .then(
21      () => { /** ready to use. The `mongoose.connect()` promise resolves to undefined. */ },
22    ).catch(err => {
23      logService.log(`error`, `MongoDB connection error. Please make sure MongoDB is running`, err);
24      process.exit(1);
25    });
26  }