printer-gui

Django web app for RPi to handle print jobs using a connected CUPS printer.

Changes

• Capturing stderr from subprocesses to convey errors to the user.
• Leveraging Django's Messages Framework to display statuses and exceptions.
• Implementing libreoffice for PDF conversion instead of pandoc.
• Re-designed UI for better look/feel. -- Improved mobile/overall experience.
• Added a favicon to better distinguish the browser tab.

Requirements

• Raspberry Pi or similar SBC with networking capability
• Python 3.8+ and the pip package installer on the SBC's OS.
• A network printer connected on the local network

Limitations

• Only pdf, doc, docx, odt, and rtf are supported.
• It seems that some printers may not respect page orientation chosen.
• No sessions.

Because I have not yet implemented sessions, if someone clicks

"Print Files" while another person on the network is uploading

some files, whatever that other person has uploaded will print

and be cleared from the queue as well. Not a big deal in my

house but I may implement separate sessions in the future to

address this flaw.

Setup

Follow the steps below to convert your single-board computer

into a printer server on your local network.

1) Connect your printer via CUPS

On your single-board computer, you will first need to connect

to your printer using CUPS. I was not in the mood for reading

command-line documentation and was able to set this up in a

few minutes using the CUPS web GUI. There are many tutorials

on how to do this such as this one.

2) Install some necessary utilities

My printer server handles PDFs, as well as doc, docx, odt, and rtf

formats. Since the 'lp' command-line utility is called for printing,

all formats that are not PDFs are converted to PDF using LibreOffice.

In the future, I may experiment with converting images to PDF format.

Anyhow, the following utilities need to be installed:

- cups 2.3.3

- default-jre 2:1.11

- libreoffice-core 1:7.0.4

- libreoffice-common 1:7.0.4

- libreoffice-java-common 1:7.0.4

- libreoffice-writer 1:7.0.4

If you are using a Raspberry Pi with Raspberry Pi OS or if you are

using a similar Debian distribution, you may use the initial_setup.py

script to install the above packages.

3) Setup the virtualenv

You will need to create your Python virtualenv in the root

directory for this project, activate it and install the

required packages:

python3 -m venv venv
source venv/bin/activate
pip3 install -r requirements.txt

4) Run the initial_setup script

This script must be run within the Django shell. With the

virtualenv enabled (source venv/bin/activate), enter the

following commands from the root directory of this repository:

python3 manage.py shell
exec(open('initial_setup.py').read())

Follow the prompts until the script is finished and the shell is closed.

5) Give your device a static IP

You will, of course, need a static IP address. On Raspberry Pi

OS, you can configure your IP address in /etc/dhcpcd.conf by

setting "static ip_address", "static domain_name_servers", and

"static routers". A simple example is given below:

interface wlan0
  static ip_address=192.168.1.4
  static domain_name_servers=192.168.1.1
  static routers=192.168.1.1

6) Add your IP address in printer/settings.py

Open the settings.py file and enter your server's IP address as

a string in the ALLOWED_HOSTS list.

7) Configure the scripts

Assuming you have cloned this repository in the '/home/pi'

directory, you will only need to change the IP address

in the 'start.bash' script to the static IP address you have

set. You can run the server by executing this script and enter

Ctrl-C to exit it:

./start.bash
Watching for file changes with StatReloader
Performing system checks...

System check identified no issues (0 silenced).
January 04, 2021 - 17:40:26
Django version 3.1, using settings 'printer.settings'
Starting development server at http://192.168.1.133:8000/
Quit the server with CONTROL-C.

Assuming the server runs correctly, you may configure the

server to run automatically on startup as a systemd service.

On the Raspberry Pi, copy the 'printerserver.service' file

to '/etc/systemd/system/', start it, and enable it.

sudo cp /home/pi/printer-gui/printerserver.service /etc/systemd/system/
sudo systemctl start printerserver
sudo systemctl enable printerserver

To check the status of the service and debug, use:

systemctl status printerserver, and

sudo journalctl -u printerserver

8) Configure the server to use your printer

The printer server has not yet been configured to use your

CUPS printer profile. With the server running, visit its

URL in a web browser from a device on the same network

(e.g. http://192.168.1.4:8000). Locate and click the

settings icon as pictured below:

As you can see in the picture, you can also set a title and

defaults for the print server. Now the server should be able

to print correctly. Upload some test files, configure the

options, and print out the files if you wish.