rudransh404/cups repository overview

⁠CUPS Printing Stack

Containerized CUPS printing stack with cups-filters, Ghostscript, and Poppler for full printing support.

⁠Introduction

The cups Docker image provides a complete printing stack, including CUPS, cups-filters, Ghostscript, and Poppler (for PostScript and PDF interpretation). This image delivers everything needed for printing (except printer-specific drivers) in a containerized environment. It’s designed for:

1. A printing stack for purely container-based systems (e.g., Ubuntu Core).
2. Replacing a classic Linux system’s printing packages with a Dockerized solution (future Ubuntu Desktop candidate).

⁠Prerequisites

• cups-ipp-utils & cups-client: Install on the Docker host:

sudo apt-get update
sudo apt-get install cups-ipp-utils cups-client -y

⁠Pulling the Image

To pull the image from Docker Hub, run:

sudo docker pull rudransh404/cups

⁠Running the Container

Run the container:

sudo docker run -d \
    --name cups \
    --network host \
    -e CUPS_PORT=<CUPS_PORT> \
    -e CUPS_ADMIN=<CUPS_ADMIN> \
    -e CUPS_PASSWORD=<CUPS_PASSWORD> \
    -v /dev/bus/usb:/dev/bus/usb:ro \
    --device-cgroup-rule='c 189:* rmw' \
    rudransh404/cups:latest

⁠Parameters:

• CUPS_PORT (optional): Sets the CUPS port (default: 631).
• CUPS_ADMIN & CUPS_PASSWORD (optional): Administrative credentials. If omitted, view generated credentials:

  sudo docker exec cups cat /etc/cups/cups-credentials
  

  Copy
• --network host: Required for discovering network printers.
• -v /dev/bus/usb:/dev/bus/usb:ro: Grants read-only access to USB devices.
• --device-cgroup-rule='c 189:* rmw': Ensures USB access permissions.

⁠Setting Up Locally

To build and run locally:

git clone https://github.com/rudra-iitm/cups-snap -b rudransh404
cd cups-snap

⁠Prerequisites

Install Rockcraft:

sudo snap install rockcraft --classic

⁠Build the Rock Image

rockcraft pack -v

⁠Convert to Docker Image

sudo rockcraft.skopeo --insecure-policy copy oci-archive:<rock_image> docker-daemon:cups:latest

⁠Run the Container

sudo docker run -d \
    --name cups \
    --network host \
    -e CUPS_PORT=<CUPS_PORT> \
    -e CUPS_ADMIN=<CUPS_ADMIN> \
    -e CUPS_PASSWORD=<CUPS_PASSWORD> \
    -v /dev/bus/usb:/dev/bus/usb:ro \
    --device-cgroup-rule='c 189:* rmw' \
    rudransh404/cups:latest

⁠Usage

1. Web Interface Setup Access the web UI at:

http://localhost:<port>/

Manage printers and jobs using the CUPS admin credentials.

1. CUPS Commands:

⁠Inside Container

sudo docker exec -u "${CUPS_ADMIN}" cups lpadmin -p <printer>

⁠From Host

CUPS_SERVER=localhost:<CUPS_PORT> lpstat -W completed

Note: For administrative tasks, add -U <CUPS_ADMIN> to lpadmin.

⁠Included Components

• cups v2.4.11: Core printing system.
• cups-filters v2.0.1: Filtering system for print processing.
• ghostscript v10.05.0: PostScript/PDF rendering engine.
• poppler: PDF interpreter.
• libcupsfilters v2.1.1: Print job filtering library.

⁠How It Works

• Print Processing: Ghostscript and Poppler render PostScript/PDF, with cups-filters handling job processing.
• Printer Discovery: CUPS backends detect USB and network printers via IPP, LPD, and socket protocols.
• IPP Support: Full compatibility with IPP clients for seamless printing.

⁠Summary

The cups Docker image provides a complete printing stack with CUPS, cups-filters, Ghostscript, and Poppler, supporting PostScript and PDF rendering for a wide range of printers. It offers flexible deployment for containerized systems, classic Linux replacements, or as a secure printing proxy, with robust IPP support and network discovery.