MiniPrint - Zebra Printer API Server

This Flask application provides a REST API to interact with Zebra label printers on a network. It supports listing all registered printers, checking their online status, and sending ZPL commands to print labels directly from supplied text.

Features

• ERP-backed Printers: Loads the list of printers from an ERPNext DocType (default: NPrint Printer).
• List Printers: Retrieve the current mapping with IP and port as seen by the server.
• Check Printer Status: Check the online/offline status of each printer.
• Print Labels: Send text to a printer to be printed on a label using Zebra Programming Language (ZPL).
• Manual Reload: POST /printers/reload to re-fetch the printer list from ERP immediately.
• Auto Refresh: Optional background refresh on an interval via PRINTERS_REFRESH_SECONDS.

Setup

Prerequisites

• Python 3.6 or higher
• Flask

Installation

1. Clone the repository:

   git clone https://github.com/newmatik/miniprint.git
   cd miniprint

2. Set up a virtual environment (optional but recommended):

   python -m venv venv
   source venv/bin/activate  # On Windows use `venv\Scripts\activate`

3. Install dependencies:

   pip install -r requirements.txt

4. Environment setup: Copy .env_sample to .env and set the variables. At minimum set APIKEY, ERP_URL, ERP_API_KEY, and ERP_API_SECRET.

   cp .env_sample .env
   vim .env

   • ERP_PRINTER_DOCTYPE (optional, defaults to NPrint Printer)
   • PRINTERS_REFRESH_SECONDS (optional; set to 0 to disable, e.g., 3600 for hourly refresh)
   • Note: If ERP is unreachable or returns no rows, the server falls back to the local mapping defined in printers.py.

5. Running the Server: Run the server with the following command:

   flask run

   This starts the server on http://0.0.0.0:5500/, making it accessible on all network interfaces on port 5500.

Usage

• GET /printers Requires API key Returns a list of all printers

• GET /printers/status Requires API key Returns the status of each printer (online, offline)

• POST /printers/reload Requires API key Forces an immediate reload of printers from ERPNext.

• POST /print Requires API key Prints the ZPL label to the specified printer

Example Request

Using curl to check printer status:

curl -X GET http://localhost:5500/printers/status -H "apikey: g9d8fh09df8hg09f8siw3erfsd8"

Reload printers from ERP:

curl -X POST http://localhost:5500/printers/reload -H "apikey: $APIKEY"

List the current mapping:

curl -X GET http://localhost:5500/printers -H "apikey: $APIKEY"

ERPNext integration

• The server queries ERPNext’s built-in REST API at /api/resource/<DocType> using the API key/secret.
• Expected fields on the DocType (defaults to NPrint Printer):
  • printer_name: unique identifier used by clients to select a printer
  • server_ip: IPv4/hostname of the device
  • port: TCP port (default 9100 if not set)
• Optional: configure an ERPNext Webhook on the DocType to call POST /printers/reload after insert/update for near-real-time updates. Keep PRINTERS_REFRESH_SECONDS as a fallback.

Deployment on Ubuntu Server

To ensure that the Flask application starts automatically at server boot and restarts in case it crashes, we use systemd on Ubuntu. Consider deploying with a production-ready WSGI server like Gunicorn.

Create a Service File

First, create a systemd service file for your Flask application. You’ll need root or sudo privileges to write to the service directory.

Open a terminal and use your preferred text editor to create a service file:

sudo nano /etc/systemd/system/miniprint.service

Add the following configuration to the file, customizing it to suit your application setup:

[Unit]
Description=Flask Application Service
After=network.target

[Service]
User=your_username
Group=your_usergroup
WorkingDirectory=/path/to/your/application
Environment="PATH=/path/to/your/venv/bin"
ExecStart=/path/to/your/venv/bin/python app.py
Restart=always

[Install]
WantedBy=multi-user.target

Enable and Start the Service

After saving your service file, you'll need to reload the systemd manager configuration, enable the service to start on boot, and then start the service:

sudo systemctl daemon-reload
sudo systemctl enable miniprint.service
sudo systemctl start miniprint.service

Check the Status of Your Service

To check the status of your service and ensure it's running properly:

sudo systemctl status miniprint.service

Note

This application is designed for demonstration and development purposes and may require additional security and error handling features for production use.