Receipt Relay

Containerized Python service that listens for Signal messages and provides a small web UI for printing text or images to an Epson TM-T20III receipt printer.

Features

• FastAPI web interface with form at / and print endpoint at /print.
• Prints a header with the current date/time and a footer rule.
• Basic Markdown wrapping.
• Image processing with Pillow for scaling and dithering.
• ESC/POS output using python-escpos over USB.
• Dockerfile and docker-compose setup including signal-cli sidecar.

Development

pip install -r requirements.txt
uvicorn receipt_relay.web.main:app --reload

Visit http://localhost:8081/ to access the form.

Testing

pytest

Docker

The included docker-compose.yml runs the web service and the Signal sidecar. Set the required SIGNAL_NUMBER and ALLOWED_SENDERS environment variables before starting.

docker compose up --build