How to connect to mongodb behind nginx with nodejs on same server

Question

I have created a droplet via DigitalOcean with Ubuntu 16.04. I want to deploy my website on the server and I need my nodejs app and mongodb on the server.

I had no problem setting up the nodejs app. I am using pm2 with nginx as reverse proxy and letsencrypt for https.

So, to the problem. I have no idea how to connect to my mongodb server. I have installed mongodb. When I run sudo systemctl status mongodb this comes in the output:

    mongodb.service - High-performance, schema-free document-oriented database
   Loaded: loaded (/etc/systemd/system/mongodb.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2017-06-28 13:12:41 UTC; 2h 4min ago
 Main PID: 13918 (mongod)
    Tasks: 20
   Memory: 61.9M
      CPU: 1min 21.003s
   CGroup: /system.slice/mongodb.service
           └─13918 /usr/bin/mongod --quiet --config /etc/mongod.conf

Log file looks like this after start of mongod:

2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] MongoDB starting : pid=13918 port=27017 dbpath=/var/lib/mo$
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] db version v3.2.14
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] git version: 92f6668a768ebf294bd4f494c50f48459198e6a3
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] OpenSSL version: OpenSSL 1.0.2g  1 Mar 2016
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] allocator: tcmalloc
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] modules: none
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] build environment:
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten]     distmod: ubuntu1604
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten]     distarch: x86_64
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten]     target_arch: x86_64
2017-06-28T13:12:41.583+0000 I CONTROL  [initandlisten] options: { config: "/etc/mongod.conf", net: { bindIp: "127$
2017-06-28T13:12:41.643+0000 I -        [initandlisten] Detected data files in /var/lib/mongodb created by the 'wi$
2017-06-28T13:12:41.643+0000 I STORAGE  [initandlisten] wiredtiger_open config: create,cache_size=1G,session_max=2$
2017-06-28T13:12:42.482+0000 I CONTROL  [initandlisten]
2017-06-28T13:12:42.483+0000 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is$
2017-06-28T13:12:42.483+0000 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2017-06-28T13:12:42.483+0000 I CONTROL  [initandlisten]
2017-06-28T13:12:42.483+0000 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is $
2017-06-28T13:12:42.483+0000 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2017-06-28T13:12:42.483+0000 I CONTROL  [initandlisten]
2017-06-28T13:12:42.491+0000 I FTDC     [initandlisten] Initializing full-time diagnostic data capture with direct$
2017-06-28T13:12:42.491+0000 I NETWORK  [initandlisten] waiting for connections on port 27017
2017-06-28T13:12:42.491+0000 I NETWORK  [HostnameCanonicalizationWorker] Starting hostname canonicalization worker

My config files looks like this:

# mongod.conf

# for documentation of all options, see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# Where and how to store data.
storage:
  dbPath: /var/lib/mongodb
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# network interfaces
net:
  port: 27017
  bind

Ip: 127.0.0.1


#processManagement:

#security:

#operationProfiling:

#repli

cation:

#sharding:

## Enterprise-Only Options:

#auditLog:

#snmp:

I have for example tried this without luck:

mongoose.connect('mongodb://127.0.0.1:27017/DB');

The big question is how I should connect to the mongodb database that we can see are running as it should, as we can see in the logs. Do I have to configure nginx to get this to work or do I have the wrong url?

Thanks for the help!