CUPS Docker Auto-Builder 🖨️

A fully automated, multi-architecture Docker setup for the Common UNIX Printing System (CUPS).

This repository doesn't just host a Dockerfile. It uses a "smart polling" GitHub Actions workflow to check for new stable releases from the official OpenPrinting repository and automatically builds a fresh Docker image whenever a new version is out.

✨ Features

• Always Up-to-Date: The GitHub Actions workflow checks for new upstream releases every 3 hours. If a new version is detected, it builds and pushes a new image automatically.
• Multi-Architecture: Built for both linux/amd64 (standard PCs/servers) and linux/arm64 (perfect for ARM-based boards like Raspberry Pi).
• Portainer & Watchtower Ready: Designed to be easily deployed via Docker Compose and seamlessly updated in the background using Watchtower.
• Pre-configured Web UI Access: Comes with a default admin user and pre-configured network settings to allow remote access to the CUPS Web Interface right out of the box.

🚀 Quick Start (Docker Compose)

To deploy this container, you can use the following docker-compose.yml file. It is optimized for environments like Portainer.

version: '3.8'

services:
  cups:
    image: ghcr.io/dtsypkin/openprinting-cups-docker:latest
    container_name: cups-server
    restart: unless-stopped
    ports:
      - "631:631"
    volumes:
      # Stores printer configurations and system settings
      - cups_config:/etc/cups
      
      # Stores the print queue and cache
      # Recommendation: Bind mount to a fast external SSD if available
      - cups_spool:/var/spool/cups
      
    devices:
      # Crucial for USB printer passthrough
      - /dev/bus/usb:/dev/bus/usb
      
    labels:
      # Explicitly enable Watchtower automatic updates for this container
      - "com.centurylinklabs.watchtower.enable=true"

volumes:
  cups_config:
  cups_spool:

⚙️ Configuration & Access

Once the container is up and running, open your web browser and navigate to:

👉 http://<your-server-ip>:631

To add printers or modify administrative settings via the Web UI, use the following default credentials:

• Username: admin
• Password: admin

🔌 Connecting Physical USB Printers

If you are using a physical printer connected via a USB cable, ensure the printer is turned on and plugged into the host machine before starting the container. The devices: - /dev/bus/usb:/dev/bus/usb directive in the Compose file passes the host's USB bus directly into the container so CUPS can detect the hardware.

🔄 How the Automation Works

1. A scheduled cron job in GitHub Actions runs every 3 hours.
2. It queries the GitHub API for the latest release tag of OpenPrinting/cups.
3. It checks this GitHub Container Registry (GHCR) to see if an image with this tag already exists.
4. If the tag is new, it triggers a multi-architecture buildx process using QEMU, compiling the CUPS source code from scratch.
5. The new image is pushed to GHCR, updating the latest tag.
6. If you have Watchtower running in your home lab, it will detect the updated latest tag and seamlessly recreate your local container.