MongoDB 4.4.18 installed on Armbian Linux x64 for Orange Pi 3 LTS

Ubiquiti UniFi controller requires MongoDB which is a real pain to install with it's various dependencies. Here are the steps I used to get it working on Armbian Linux.

First install libssl1.1. I just did an internet search for the standalone DEB file and installed it with dpkg.

wget http://launchpadlibrarian.net/475575244/libssl1.1_1.1.1f-1ubuntu2_arm64.deb
dpkg -i libssl1.1_1.1.1f-1ubuntu2_arm64.deb

Create the apt list file. Using an old Ubuntu repo as the Debian repo doesn't have the server. 

echo "deb [ arch=amd64,arm64 signed-by=/usr/share/keyrings/mongodb-server-4.4.gpg ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/4.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list

Import repo signing key

gpg --keyserver keyserver.ubuntu.com --recv-keys 656408E390CFB1F5
gpg --export --armor 656408E390CFB1F5 | sudo apt-key add -
mv /etc/apt/trusted.gpg   /usr/share/keyrings/mongodb-server-4.4.gpg

Update and if no errors install 4.4.18

apt update
apt install mongodb-org-mongos=4.4.18 mongodb-org-tools=4.4.18 mongodb-org-shell=4.4.18 mongodb-org-database-tools-extra=4.4.18 mongodb-org=4.4.18 mongodb-org-server=4.4.18

I believe only 4.4 is compatible with Raspberry Pi boards so make sure apt doesn't try to upgrade MongoDB

apt-mark hold   mongodb-org mongodb-org-database-tools-extra mongodb-org-mongos mongodb-org-server mongodb-org-shell mongodb-org-tools
apt-mark showhold

Set mongo daemon to start at boot

systemctl enable --now  mongod
systemctl status mongod

Now that MongoDB is installed and running do the actual UniFi controller install

echo 'deb [ arch=amd64,arm64 signed-by=/usr/share/keyrings/unifi-repo.gpg ] https://www.ui.com/downloads/unifi/debian stable ubiquiti' | sudo tee /etc/apt/sources.list.d/100-ubnt-unifi.list
sudo wget -O /usr/share/keyrings/unifi-repo.gpg https://dl.ui.com/unifi/unifi-repo.gpg
sudo apt-get update
apt-get install unifi -y
systemctl status unifi