Install Unifi Controller on Debian 11 (Bullseye)

install_unifi_8_debian_12.txt

# libssl1.1, the only missing mongodb dependency.
# I prefer enable oldstable in case this get backport security patches
echo "deb http://deb.debian.org/debian bullseye main" | sudo tee /etc/apt/sources.list.d/oldstable-bullseye.list

# MongoDB 4.4, [end of life Feb 2024](https://www.mongodb.com/support-policy/lifecycles)
curl -fsSL https://pgp.mongodb.com/server-4.4.asc | sudo gpg -o /usr/share/keyrings/mongodb-server-4.4.gpg --dearmor
echo "deb [ signed-by=/usr/share/keyrings/mongodb-server-4.4.gpg ] http://repo.mongodb.org/apt/debian buster/mongodb-org/4.4 main" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list
sudo apt-get update && sudo apt-get install mongodb-org-server -y

# Unifi
sudo apt-get update && sudo apt-get install -y ca-certificates apt-transport-https
curl -fsSL https://dl.ui.com/unifi/unifi-repo.gpg | sudo gpg -o /usr/share/keyrings/unifi-repo.gpg --dearmor
echo 'deb [ 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 apt-get update && sudo apt-get install unifi -y

I'll note that if you're going with a very minimal Debian 12 install, you'll need to install curl and gpg
sudo apt install gpg curl -y

Otherwise worked perfectly - excellent guide.

wget http://ftp.au.debian.org/debian/pool/main/o/openssl/libssl1.1_1.1.1w-0+deb11u1_amd64.debD
sudo dpkg -i libssl1.1_1.1.1w-0+deb11u1_amd64.deb