Raspberry Pi CPU Temp & Fan Monitor

Minimal FastAPI + Tailwind web UI that shows live CPU temperature and Raspberry Pi 5 Active Cooler fan speed (RPM + % of 8000 max). The backend only reads when the browser polls /api/stats, so no commands or sysfs reads occur when nobody is connected.

Requirements

• Raspberry Pi OS with vcgencmd available (usually /usr/bin/vcgencmd)
• Docker and Docker Compose

Run with Docker Compose

docker compose build
docker compose up -d

Then open http://<raspberry-pi-ip>:9000/ in your browser.

Notes on mounts/devices

• docker-compose.yml bind-mounts:
  • /usr/bin/vcgencmd:/usr/bin/vcgencmd:ro for temperature.
  • /sys:/sys:ro so the app can find /sys/devices/platform/cooling_fan/hwmon*/fan1_input for fan RPM.
• Devices:
  • Raspberry Pi 5: /dev/vcio; older Pis: /dev/vchiq. Set the devices: entry to whichever exists.
• Adjust the vcgencmd path if which vcgencmd differs on your Pi.
• If permission issues arise, you can try uncommenting privileged: true (not recommended unless necessary).

Project structure

• main.py — FastAPI app with / (HTML) and /api/stats (JSON: temp + fan rpm/%).
• templates/index.html — Tailwind CDN UI with 1s polling, starts/stops on focus/blur; shows temp, fan rpm, fan percent, diagnostics.
• requirements.txt — Python deps (fastapi, uvicorn, jinja2).
• Dockerfile, docker-compose.yml — Container build/run setup for Pi.

Local (non-Docker) run

python -m venv .venv
source .venv/bin/activate    # on Windows: .venv\\Scripts\\activate
pip install -r requirements.txt
uvicorn main:app --host 0.0.0.0 --port 9000

Visit http://localhost:9000/.