Just-in-time label printing on the Zebra ZP450 using node.js + Easypost + Pusher + cups

README.md

This is the script we use at yerdle to print labels from our Rails backend to our Zebra ZP450 printer.

See this blog post for the whole story.

zebra-client.js.coffee

dotenv = require('dotenv')
dotenv.load()

PusherClient = require('pusher-node-client').PusherClient
easypost = require('node-easypost')(process.env.EASYPOST_SECRET_KEY)
child_process = require('child_process')
fs = require('fs')
request = require('request')

pusher_client = new PusherClient
  appId: process.env.PUSHER_APP_ID
  key: process.env.PUSHER_KEY
  secret: process.env.PUSHER_SECRET

pres = null
pusher_client.on 'connect', () ->
  pres = pusher_client.subscribe("shipments")
  pres.on 'new', (data) ->
    console.log "shipment #{data.easypost_shipment_id} with tracking number #{data.tracking_code}"

    easypost.Shipment.retrieve data.easypost_shipment_id, (err, shipment) ->
      console.log("ERROR: #{err}") if err

      shipment.label {file_format: 'zpl'}, (err, shipment) ->
        console.log("ERROR: #{err}") if err
        console.log "Fetching #{shipment.postage_label.label_zpl_url}"
        lpr = child_process.spawn "lpr", ['-P', process.env.ZEBRA_PRINT_QUEUE_NAME, '-o', 'raw']
        request(shipment.postage_label.label_zpl_url).pipe(lpr.stdin)
        lpr.on 'close', (code) ->
          console.log "Child process exit with code #{code}"


pusher_client.connect()