Label Server

A REST API server for printing labels on Dymo labelwriters via CUPS.

Prerequisites

• Rust (installed automatically if not present)
• CUPS system with Dymo labelwriter configured
• Dymo labelwriter connected via USB

Setup

1. Ensure your Dymo labelwriter is connected and configured in CUPS:

   lpstat -p  # List available printers

2. Build and run the server:

   cargo run

The server will start on http://0.0.0.0:3000

Web Interface

The server includes a web interface accessible at http://localhost:3000 that provides:

• 4 text input fields for label content
• Label format selection dropdown (default: 99012)
• Print button with status feedback
• Clean, responsive design for easy label printing

API Endpoints

Health Check

GET /
GET /health

Returns server status and version.

List Printers

GET /printers

Returns a list of available printers.

Print Label

POST /print
Content-Type: application/json

{
  "line1": "John Doe",                     // Required - First line of text
  "line2": "123 Main Street",              // Optional - Second line of text
  "line3": "Anytown, NY 12345",            // Optional - Third line of text
  "line4": "USA",                          // Optional - Fourth line of text
  "printer_name": "DYMO_LabelWriter_450",  // Optional
  "label_size": "30252"                    // Optional - Dymo label size code
}

• line1 is required and cannot be empty
• line2, line3, and line4 are optional
• Empty lines are automatically filtered out when printing
• If printer_name is not specified, the server will automatically find the first available Dymo printer
• If label_size is not specified, it defaults to "30252" (standard Dymo address label)

Common Dymo Label Sizes

• 30252 - Address labels (1-1/8" x 3-1/2")
• 30256 - Shipping labels (2-5/16" x 4")
• 30321 - Large address labels (1-4/10" x 3-1/2")
• 30330 - Return address labels (3/4" x 2")
• 99012 - Large address labels (3-1/2" x 1-1/8")

Example Usage

# Check server health
curl http://localhost:3000/health

# List available printers
curl http://localhost:3000/printers

# Print a simple one-line label
curl -X POST http://localhost:3000/print \
  -H "Content-Type: application/json" \
  -d '{"line1": "Hello, World!"}'

# Print a complete address label
curl -X POST http://localhost:3000/print \
  -H "Content-Type: application/json" \
  -d '{
    "line1": "John Doe",
    "line2": "123 Main Street",
    "line3": "Anytown, NY 12345",
    "line4": "USA"
  }'

# Print to specific printer
curl -X POST http://localhost:3000/print \
  -H "Content-Type: application/json" \
  -d '{
    "line1": "Jane Smith",
    "line2": "456 Oak Avenue",
    "printer_name": "DYMO_LabelWriter_450"
  }'

# Print with custom label size (shipping label)
curl -X POST http://localhost:3000/print \
  -H "Content-Type: application/json" \
  -d '{
    "line1": "URGENT DELIVERY",
    "line2": "ABC Company",
    "line3": "789 Business Blvd",
    "label_size": "30256"
  }'

# Print return address with small label size
curl -X POST http://localhost:3000/print \
  -H "Content-Type: application/json" \
  -d '{
    "line1": "From: My Company",
    "line2": "PO Box 123",
    "printer_name": "DYMO_LabelWriter_450",
    "label_size": "30330"
  }'

Configuration

The server uses default Dymo label size (30252) when no label_size is specified in the request. You can override this per-request by including a label_size parameter in your print requests.

Running as a Service (Raspberry Pi / Debian)

For production deployment on a Raspberry Pi or Debian-based system, you can set up the label server as a systemd service to automatically start on boot and restart on crashes.

Prerequisites for Raspberry Pi

1. Install CUPS and Dymo drivers:

   sudo apt update
   sudo apt install cups cups-client printer-driver-dymo

2. Configure CUPS to accept connections:

   sudo usermod -a -G lpadmin pi
   sudo systemctl enable cups
   sudo systemctl start cups

3. Connect and configure your Dymo printer via CUPS web interface:

   # Access CUPS web interface at http://your-pi-ip:631
   # Or configure via command line:
   sudo lpadmin -p DYMO_LabelWriter_450 -E -v usb://DYMO/LabelWriter%20450 -m dymo_lw450.ppd

   Detailed Setup Guide: For a comprehensive step-by-step guide on setting up a Raspberry Pi as a print server for Dymo label printers, including CUPS configuration and troubleshooting, see: Configure a Raspberry Pi as a Print Server for Dymo Label Printers

Build and Install for Production

For x86_64 Systems (Standard)

1. Build the optimized release binary:

   cd /path/to/labelserver
   cargo build --release

For Raspberry Pi 2/3 (32-bit ARMv7)

If you're building on a different architecture (e.g., x86_64) to deploy on Raspberry Pi 2 with 32-bit Debian Bookworm:

1. Install cross-compilation tools:

   # Install Rust ARM target (musl for better compatibility)
   rustup target add arm-unknown-linux-musleabihf
   
   # Install ARM cross-compiler (on Ubuntu/Debian)
   sudo apt install gcc-arm-linux-gnueabihf

2. Create cargo cross-compilation config:

   mkdir -p .cargo
   echo '[target.arm-unknown-linux-musleabihf]
   linker = "arm-linux-gnueabihf-gcc"' > .cargo/config.toml

3. Build for ARM:

   cargo build --release --target arm-unknown-linux-musleabihf

   The ARM binary will be located at: target/arm-unknown-linux-musleabihf/release/labelserver

   Note: This uses musl libc for static linking, making it compatible with older glibc versions on Raspberry Pi systems.

Install the Binary and Static Files

Create installation directory:

sudo mkdir -p /opt/labelserver/static

For x86_64 deployment:

sudo cp target/release/labelserver /opt/labelserver/
sudo cp static/index.html /opt/labelserver/static/
sudo chmod +x /opt/labelserver/labelserver

For Raspberry Pi 2 deployment:

sudo cp target/arm-unknown-linux-musleabihf/release/labelserver /opt/labelserver/
sudo cp static/index.html /opt/labelserver/static/
sudo chmod +x /opt/labelserver/labelserver

Set ownership and create symlink:

# Set ownership
sudo chown -R labelserver:labelserver /opt/labelserver

# Create symlink for easy access (optional)
sudo ln -sf /opt/labelserver/labelserver /usr/local/bin/labelserver

Create a Dedicated User (Optional but Recommended)

sudo useradd --system --shell /bin/false --home /opt/labelserver labelserver

Create Systemd Service

1. Create the service file:

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

2. Add the following configuration:

   [Unit]
   Description=Label Server - Dymo Label Printer REST API
   Documentation=https://github.com/your-repo/labelserver
   After=network-online.target cups.service
   Wants=network-online.target
   Requires=cups.service
   
   [Service]
   Type=simple
   User=labelserver
   Group=lp
   ExecStart=/opt/labelserver/labelserver
   WorkingDirectory=/opt/labelserver
   Environment=RUST_LOG=info
   
   # Restart policy
   Restart=always
   RestartSec=5
   
   # Security settings
   NoNewPrivileges=yes
   PrivateTmp=yes
   ProtectSystem=strict
   ProtectHome=yes
   ReadWritePaths=/opt/labelserver
   
   # Resource limits
   LimitNOFILE=1024
   
   [Install]
   WantedBy=multi-user.target

Service Management

1. Reload systemd and enable the service:

   sudo systemctl daemon-reload
   sudo systemctl enable labelserver.service

2. Start the service:

   sudo systemctl start labelserver.service

3. Check service status:

   sudo systemctl status labelserver.service

4. View service logs:

   # View recent logs
   sudo journalctl -u labelserver.service -f
   
   # View logs since boot
   sudo journalctl -u labelserver.service --since today
   
   # View last 50 log entries
   sudo journalctl -u labelserver.service -n 50

5. Stop or restart the service:

   sudo systemctl stop labelserver.service
   sudo systemctl restart labelserver.service

6. Disable auto-start (if needed):

   sudo systemctl disable labelserver.service

Service Troubleshooting

• Check if the service is running:

  sudo systemctl is-active labelserver.service

• Check if the service is enabled for boot:

  sudo systemctl is-enabled labelserver.service

• Test the binary manually:

  /opt/labelserver/labelserver

• Check CUPS dependencies:

  sudo systemctl status cups.service
  lpstat -p  # Should show your Dymo printer

• Verify network connectivity:

  curl http://localhost:3000/health

• Check service permissions:

  # Ensure the labelserver user can access CUPS
  groups labelserver  # Should include 'lp' group

Updating the Service

When updating the label server:

1. Stop the service:

   sudo systemctl stop labelserver.service

2. Update the binary and static files:

   For x86_64:

   cargo build --release
   sudo cp target/release/labelserver /opt/labelserver/
   sudo cp static/index.html /opt/labelserver/static/

   For Raspberry Pi 2:

   cargo build --release --target arm-unknown-linux-musleabihf
   sudo cp target/arm-unknown-linux-musleabihf/release/labelserver /opt/labelserver/
   sudo cp static/index.html /opt/labelserver/static/

3. Start the service:

   sudo systemctl start labelserver.service

Troubleshooting

• Ensure CUPS is running: systemctl status cups
• Check printer status: lpstat -p
• Verify printer queues: lpq -P your_printer_name