How to run a MongoDB instance on a specific port and activate authentification?

Sometimes you need to work on different projects that need MongoDB in differents ports /instances, We have a lot of situations for which that happens but I will not list them here. I faced that situation and I diced to share my experience on it with you.

In this tutorial you will learn how to run a specific instance of MongoDB :

• Store the database files in a specific directory
• Specify a custom port
• Activate authentification by username and password
• How to connect from mongo client directly from the terminal

Requirement

• Have MongoDB 3.4 or higher installed

Create the directories to persist your data

mkdir /home/memel/data
mkdir /home/memel/data/log

Create a Configuration file

Everything can be done in the config file.
create a file anywhere you want and keep in mind the full path of that file.

Name it externaldb.conf :

touch /home/memel/externaldb.conf

Put content below and adapt it to your need :

systemLog:
   destination: file
# you can put the corresponding path for the log
   path: /home/memel/data/external/log/mongod.log
   logAppend: true
storage:
   journal:
      enabled: true
# you can put the corresponding path to store the DB
   dbPath: /home/memel/data/external
net:
   bindIp: 127.0.0.1
# put the port that you want
   port: 27020
setParameter:
   enableLocalhostAuthBypass: false

From your terminal run the following to lunch your instance :

mongod --config "/home/memel/externaldb.conf"

To check if everything is ok, from you terminal run :

mongo --port 27020

Create a secured account

Select the admin database

use admin

Create a server admin user

db.createUser(
{
user: "sa",
pwd: "your password",
roles: [ { role: "userAdminAnyDatabase", db: "admin" }, "readWriteAnyDatabase" ]
})

That user account will manage all the server, I mean all the databases.
you can create a user only for a specific database.

Create a database admin user

Creating a specific account myAppUser that will acceed only your app database myAppDB.

db.createUser(
{
user: "myAppUser",
pwd: "your password",
roles: [ { role: "readWrite", db: "myAppDB" }]
})

You should see a success message, close your terminal.

Connect from mongo client

Now open a new terminal and test if the sa account works, run the next command line

mongo --port 27020  -u sa -p --authenticationDatabase admin

Activate full authentification

Activate the security allow only access by password
you just need to set enableLocalhostAuthBypass to true
your config file should look like this

systemLog:
   destination: file
# you can put the corresponding path for the log
   path: /home/memel/data/external/log/mongod.log
   logAppend: true
storage:
   journal:
      enabled: true
# you can put the corresponding path to store the DB
   dbPath: /home/memel/data/external
net:
   bindIp: 127.0.0.1
# put the port that you want
   port: 27020
setParameter:
   enableLocalhostAuthBypass: true

Enjoy !!!