Install & Configure MongoDB on the Raspberry Pi

#Prerequisites

You will need:

• A Raspberry Pi 3 or 4
• A suitably sized Micro SD card (I used a 16 Gb card)
• A computer and SD card reader to write the SD card image. (This can be another Raspberry Pi, but I'm using my desktop PC)
• A text editor on the host computer. (I recommend VS Code)

#What This Tutorial Will Do

This tutorial will show you how to:

• Install the 64-bit version of Ubuntu Server on your Raspberry Pi.
• Configure it to connect to your WiFi.
• Correctly install MongoDB onto your Pi.
• Add a user account, so you can safely expose MongoDB on your home network.

When you're done, you'll have a secured MongoDB instance available on your home network.

#Things Not To Do

Do not run apt install mongodb on your Raspberry Pi, or indeed any Linux computer! The versions of MongoDB shipped with Linux distributions are very out of date. They won't run as well, and some of them are so old they're no longer supported.

MongoDB provide versions of the database, pre-packaged for many different operating systems, and Ubuntu Server on Raspberry Pi is one of them.

#Installing Ubuntu

Download and install the Raspberry Pi Imager for your host computer.

Run the Raspberry Pi Imager, and select Ubuntu Server 20.04, 64-bit for Raspberry Pi 3/4.

Make sure you don't accidentally select Ubuntu Core, or a 32-bit version.

Insert your Micro SD Card into your computer and select it in the Raspberry Pi Imager window.

Click Write and wait for the image to be written to the SD Card. This may take some time! When it's finished, close the Raspberry Pi Imager. Then remove the Micro SD Card from your computer, and re-insert it.

The Ubuntu image for Raspberry Pi uses cloud-init to configure the system at boot time. This means that in your SD card system-boot volume, there should be a YAML file, called network-config. Open this file in VS Code (or your favourite text editor).

Edit it so that it looks like the following. The indentation is important, and it's the 'wifis' section that you're editing to match your wifi configuration. Replace 'YOUR-WIFI-SSD' with your WiFi's name, and 'YOUR-WIFI-PASSWORD' with your WiFi password.

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version: 2
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ethernets:
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   eth0:
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      dhcp4: true
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      optional: true
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wifis:
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   wlan0:
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      dhcp4: true
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      optional: true
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      access-points:
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         "YOUR-WIFI-SSID":
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            password: "YOUR-WIFI-PASSWORD"

Now eject the SD card (safely!) from your computer, insert it into the Pi, and power it up! It may take a few minutes to start up, at least the first time. You'll need to monitor your network to wait for the Pi to connect. When it does, ssh into the Pi with ssh ubuntu@<raspberry-pi-ip-address>. The password is also ubuntu.

You'll be prompted to change your password to something secret.

Once you've set your password update the operating system by running the following commands:

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sudo apt update
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sudo apt upgrade

#Install MongoDB

Now let's install MongoDB. This is done as follows:

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# Install the MongoDB 4.4 GPG key:
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wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | sudo apt-key add -
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# Add the source location for the MongoDB packages:
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echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/4.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list
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# Download the package details for the MongoDB packages:
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sudo apt-get update
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# Install MongoDB:
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sudo apt-get install -y mongodb-org

The instructions above have mostly been taken from Install MongoDB Community Edition on Ubuntu

#Run MongoDB

Ubuntu 20.04 uses Systemd to run background services, so to set up mongod to run in the background, you need to enable and start the service:

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# Ensure mongod config is picked up:
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sudo systemctl daemon-reload
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# Tell systemd to run mongod on reboot:
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sudo systemctl enable mongod
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# Start up mongod!
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sudo systemctl start mongod

Now, you can check to see if the service is running correctly by executing the following command. You should see something like the output below it:

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$ sudo systemctl status mongod
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● mongod.service - MongoDB Database Server
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   Loaded: loaded (/lib/systemd/system/mongod.service; enabled; vendor preset: enabled)
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   Active: active (running) since Tue 2020-08-09 08:09:07 UTC; 4s ago
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   Docs: https://docs.mongodb.org/manual
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Main PID: 2366 (mongod)
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   CGroup: /system.slice/mongod.service
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         └─2366 /usr/bin/mongod --config /etc/mongod.conf

If your service is running correctly, you can run the MongoDB client, mongo, from the command-line to connect:

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# Connect to the local mongod, on the default port:
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$ mongo
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MongoDB shell version v4.4.0
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connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
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Implicit session: session { "id" : UUID("576ec12b-6c1a-4382-8fae-8b6140e76d51") }
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MongoDB server version: 4.4.0
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---
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The server generated these startup warnings when booting:
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      2020-08-09T08:09:08.697+00:00: Using the XFS filesystem is strongly recommended with the WiredTiger storage engine. See http://dochub.mongodb.org/core/prodnotes-filesystem
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      2020-08-09T08:09:10.712+00:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
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---
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---
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      Enable MongoDB's free cloud-based monitoring service, which will then receive and display
      metrics about your deployment (disk utilization, CPU, operation statistics, etc).

      The monitoring data will be available on a MongoDB website with a unique URL accessible to you
      and anyone you share the URL with. MongoDB may use this information to make product
      improvements and to suggest MongoDB products and deployment options to you.

      To enable free monitoring, run the following command: db.enableFreeMonitoring()
      To permanently disable this reminder, run the following command: db.disableFreeMonitoring()
---

First, check the warnings. You can ignore the recommendation to run the XFS filesystem, as this is just a small, local install. The warning about access control not being enabled for the database is important though! You'll fix that in the next section. At this point, if you feel like it, you can enable the free monitoring that MongoDB provides, by running db.enableFreeMonitoring() inside the mongo shell.

#Securing MongoDB

Here's the next, essential steps, that other tutorials miss out, for some reason. Recent versions of mongod won't connect to the network unless user authentication has been configured. Because of this, at the moment your database is only accessible from the Raspberry Pi itself. This may actually be fine, if like me, the services you're running with MongoDB are running on the same device. It's still a good idea to set a username and password on the database.

Here's how you do that, inside mongo (replace SUPERSECRETPASSWORD with an actual secret password!):

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use admin
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db.createUser( { user: "admin",
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            pwd: "SUPERSECRETPASSWORD",
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            roles: [ "userAdminAnyDatabase",
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                     "dbAdminAnyDatabase",
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                     "readWriteAnyDatabase"] } )
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exit

The three roles listed give the admin user the ability to administer all user accounts and data in MongoDB. Make sure your password is secure. You can use a random password generator to be safe.

Now you need to reconfigure mongod to run with authentication enabled, by adding a couple of lines to /etc/mongod.conf. If you're comfortable with a terminal text editor, such as vi or emacs, use one of those. I used nano, because it's a little simpler, with sudo nano /etc/mongod.conf. Add the following two lines somewhere in the file. Like the network-config file you edited earlier, it's a YAML file, so the indentation is important!

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# These two lines must be uncommented and in the file together:
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security:
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   authorization: enabled

And finally, restart mongod:

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sudo systemctl restart mongod

Ensure that authentication is enforced by connecting mongo without authentication:

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$ mongo
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MongoDB shell version v4.4.0
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connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
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Implicit session: session { "id" : UUID("4002052b-1a39-4158-8a99-234cfd818e30") }
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MongoDB server version: 4.4.0
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> db.adminCommand({listDatabases: 1})
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{
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      "ok" : 0,
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      "errmsg" : "command listDatabases requires authentication",
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      "code" : 13,
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      "codeName" : "Unauthorized"
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}
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> exit

Ensure you've exited mongo and now test that you can connect and authenticate with the user details you created:

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$ mongo -u "admin" -p "SUPERSECRETPASSWORD"
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MongoDB shell version v4.4.0
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connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
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Implicit session: session { "id" : UUID("3dee8ec3-6e7f-4203-a6ad-976b55ea3020") }
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MongoDB server version: 4.4.0
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> db.adminCommand({listDatabases: 1})
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{
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      "databases" : [
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               {
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                        "name" : "admin",
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                        "sizeOnDisk" : 151552,
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                        "empty" : false
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               },
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               {
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                        "name" : "config",
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                        "sizeOnDisk" : 36864,
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                        "empty" : false
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               },
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               {
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                        "name" : "local",
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                        "sizeOnDisk" : 73728,
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                        "empty" : false
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               },
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               {
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                        "name" : "test",
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                        "sizeOnDisk" : 8192,
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                        "empty" : false
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               }
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      ],
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      "totalSize" : 270336,
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      "ok" : 1
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}
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> exit

#Make MongoDB Available to your Network

This step is optional! Now that you've configured authentication on your server, if you want your database to be available to other computers on your network, you need to:

• Bind MongoDb to the Raspberry Pi's public IP address
• Open up port 27017 on the Raspberry Pi's firewall.

First, edit /etc/mongod.conf again, the same way as before. This time, change the IP address to 0.0.0.0:

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# Change the bindIp to '0.0.0.0':
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net:
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   port: 27017
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   bindIp: 0.0.0.0

And restart mongod again:

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sudo systemctl restart mongod

Open up port 27017 on your Raspberry Pi's firewall:

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sudo ufw allow 27017/tcp

Now, on another computer on your network, with the MongoDB client installed, run the following to ensure that mongod is available on your network:

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# Replace YOUR-RPI-IP-ADDRESS with your Raspberry Pi's actual IP address:
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mongo --host 'YOUR-RPI-IP-ADDRESS'

If it connects, then you've successfully installed and configured MongoDB on your Raspberry Pi!

#Wrapping Up

As you can see, there are a few steps to properly installing and configuring MongoDB yourself. I hadn't done it for a while, and I'd forgotten how complicated it can be! For this reason, you should definitely consider using MongoDB Atlas where a lot of this is taken care of for you. Not only is the free-forever tier quite generous for small use-cases, there are also a bunch of extra services thrown in, such as serverless functions, charting, free-text search, and more!

You're done! Go write some code in your favourite programming language, and if you're proud of it (or even if you're just having some trouble and would like some help) let us know!. Check out all the cool blog posts on the MongoDB Developer Hub, and make sure to bookmark MongoDB Documentation