Introduction

MongoDB is a free and open-source NoSQL document database used commonly in modern web applications. This tutorial will help you set up MongoDB on your server for a production application environment.

Prerequisites

To follow this tutorial, you will need:

One Ubuntu 16.04 server set up by following this initial server setup tutorial, including a sudo non-root user and a firewall.

Step 1 — Adding the MongoDB Repository

MongoDB is already included in Ubuntu package repositories, but the official MongoDB repository provides most up-to-date version and is the recommended way of installing the software. In this step, we will add this official repository to our server.
Ubuntu ensures the authenticity of software packages by verifying that they are signed with GPG keys, so we first have to import they key for the official MongoDB repository.

wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | sudo apt-key add -

After successfully importing the key, you will see:

OK

Next, we have to add the MongoDB repository details so apt will know where to download the packages from.
Issue the following command to create a list file for MongoDB.

echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/4.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list

After adding the repository details, we need to update the packages list.

sudo apt-get update

Step 2 — Installing and Verifying MongoDB

Now we can install the MongoDB package itself.

sudo apt-get install -y mongodb-org

This command will install several packages containing latest stable version of MongoDB along with helpful management tools for the MongoDB server.
Next, start MongoDB with systemctl.

sudo systemctl start mongod

You can also use systemctl to check that the service has started properly.

sudo systemctl status mongod


● mongodb.service - High-performance, schema-free document-oriented database
   Loaded: loaded (/etc/systemd/system/mongodb.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2016-04-25 14:57:20 EDT; 1min 30s ago
 Main PID: 4093 (mongod)
    Tasks: 16 (limit: 512)
   Memory: 47.1M
      CPU: 1.224s
   CGroup: /system.slice/mongodb.service
           └─4093 /usr/bin/mongod --quiet --config /etc/mongod.conf

The last step is to enable automatically starting MongoDB when the system starts.

sudo systemctl enable mongod

The MongoDB server is now configured and running, and you can manage the MongoDB service using the systemctl command (e.g. sudo systemctl stop mongod, sudo systemctl start mongod).

Step 3 — Adjusting the Firewall (Optional)

Assuming you have followed the initial server setup tutorial instructions to enable the firewall on your server, MongoDB server will be inaccessible from the internet.
If you intend to use the MongoDB server only locally with applications running on the same server, it is a recommended and secure setting. However, if you would like to be able to connect to your MongoDB server from the internet, we have to allow the incoming connections in ufw.
To allow access to MongoDB on its default port 27017 from everywhere, you could use sudo ufw allow 27017. However, enabling internet access to MongoDB server on a default installation gives unrestricted access to the whole database server.
in most cases, MongoDB should be accessed only from certain trusted locations, such as another server hosting an application. To accomplish this task, you can allow access on MongoDB’s default port while specifying the IP address of another server that will be explicitly allowed to connect.

sudo ufw allow from your_other_server_ip/32 to any port 27017

You can verify the change in firewall settings with ufw.

sudo ufw status

You should see traffic to 27017 port allowed in the output.If you have decided to allow only a certain IP address to connect to MongoDB server, the IP address of the allowed location will be listed instead of Anywhere in the output.

Status: active

To                         Action      From
--                         ------      ----
27017                      ALLOW       Anywhere
OpenSSH                    ALLOW       Anywhere
27017 (v6)                 ALLOW       Anywhere (v6)
OpenSSH (v6)               ALLOW       Anywhere (v6)

More advanced firewall settings for restricting access to services are described in UFW Essentials: Common Firewall Rules and Commands.

Conclusion

You can find more in-depth instructions regarding MongoDB installation and configuration in these DigitalOcean community articles.