Run Developer Services & Cloud Storage on <3W: The Ultimate Ultra‑Low‑Power SBC Guide (2026)

# On your workstation
wget https://cdimage.ubuntu.com/ubuntu-server/releases/24.04/release/ubuntu-24.04-preinstalled-server-arm64+raspi.img.xz
xz -d ubuntu-24.04-preinstalled-server-arm64+raspi.img.xz
sudo dd if=ubuntu-24.04-preinstalled-server-arm64+raspi.img of=/dev/sdX bs=4M conv=fsync status=progress
sync

# After first boot, SSH in as ubuntu/ubuntu, then:
sudo apt update && sudo apt upgrade -y
sudo apt install -y docker.io fail2ban ufw
sudo systemctl enable docker ufw fail2ban
sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow ssh
sudo ufw enable

# Disable HDMI (Pi Zero) – persists across reboots
sudo systemctl mask console-setup.service
sudo sed -i 's/^#hdmi_blanking=1/hdmi_blanking=1/' /boot/firmware/config.txt

# Reduce swap usage (no swap on low‑power devices)
sudo swapoff -a
sudo sed -i '/ swap / s/^/#/' /etc/fstab

version: "3.8"
services:
  gitlab:
    image: gitlab/gitlab-ce:latest
    container_name: gitlab
    restart: unless-stopped
    environment:
      GITLAB_OMNIBUS_CONFIG: |
        external_url 'http://gitlab.local'
        gitlab_rails['gitlab_shell_ssh_port'] = 2222
    ports:
      - "80:80"
      - "443:443"
      - "2222:22"
    volumes:
      - gitlab-config:/etc/gitlab
      - gitlab-logs:/var/log/gitlab
      - gitlab-data:/var/opt/gitlab
    deploy:
      resources:
        limits:
          cpus: "0.5"
          memory: "256M"

  nextcloud:
    image: nextcloud:stable
    container_name: nextcloud
    restart: unless-stopped
    environment:
      - MYSQL_PASSWORD=nextcloud
      - MYSQL_DATABASE=nextcloud
      - MYSQL_USER=nextcloud
      - MYSQL_HOST=db
    ports:
      - "8080:80"
    volumes:
      - nextcloud-data:/var/www/html
    depends_on:
      - db
    deploy:
      resources:
        limits:
          cpus: "0.3"
          memory: "256M"

  db:
    image: mariadb:10.11
    restart: unless-stopped
    environment:
      - MYSQL_ROOT_PASSWORD=supersecret
      - MYSQL_PASSWORD=nextcloud
      - MYSQL_DATABASE=nextcloud
      - MYSQL_USER=nextcloud
    volumes:
      - db-data:/var/lib/mysql
    deploy:
      resources:
        limits:
          cpus: "0.2"
          memory: "128M"

volumes:
  gitlab-config:
  gitlab-logs:
  gitlab-data:
  nextcloud-data:
  db-data:

cd /home/ubuntu/devstack
docker compose up -d

#!/usr/bin/env bash
DEVICE="/dev/bus/usb/001/002"   # change to your power meter's bus/device
THRESHOLD=2.9   # watts
INTERVAL=60     # seconds

while true; do
  WATT=$(sudo powermon -d "$DEVICE" -r 1 | grep Watt | awk '{print $2}')
  if (( $(echo "$WATT > $THRESHOLD" | bc -l) )); then
    logger -t power-watch "Power $WATT W > $THRESHOLD W – initiating graceful shutdown"
    systemctl poweroff
    exit 0
  fi
  sleep $INTERVAL
done

sudo chmod +x /usr/local/bin/power-watch.sh
sudo systemctl enable --now power-watch.service

[Unit]
Description=Watch power consumption and shutdown on over‑draw
After=network.target

[Service]
ExecStart=/usr/local/bin/power-watch.sh
Restart=always
User=root

[Install]
WantedBy=multi-user.target

sudo apt install -y rclone
rclone config   # set up a remote called "b2"
# Schedule nightly backup of Nextcloud data
cat <<'EOF' | sudo tee /etc/cron.d/nextcloud-backup
30 2 * * * root /usr/bin/rclone sync /var/lib/docker/volumes/nextcloud-data/_data b2:my-nextcloud-backups --log-file /var/log/rclone.log
EOF