labelprint

Unified UI for printing labels/receipts:

• Native ZPL printing to a Datamax-ONeil thermal barcode printer

• A proxy/switcher in front of three brother_ql_web instances, one per Brother QL printer

• ESC/POS receipt printing to an Epson TM-T20II

Routes

• / — home page, links to everything below

• /upload, POST /upload — upload a PDF/ZPL file and print it (Datamax)

• POST /shipping/zpl — print raw ZPL text (see "API usage" below)

• /test-print — print the bundled Datamax test label

• /epson — receipt printing UI (title/body/QR template, or raw ESC/POS mnemonic notation)

• POST /epson/print — print a title/body/QR receipt

• POST /epson/raw — print already-formatted ESC/POS mnemonic notation (see "API usage" below)

• POST /epson/test-print — print an Epson capability test page (text sizes, barcode, QR, raster image)

• /labels — shared repository of saved ZPL labels / ESC-POS receipts (list, edit, preview, print, delete)

• /brother — list of Brother QL printers

• /brother/<printer>/* — proxied to that printer’s brother_ql_web instance (UI and API alike)

API usage (e.g. from Gitea Actions)

POST /shipping/zpl and POST /epson/raw are plain, unauthenticated form-POST endpoints — no session/login needed, and printing without a save_as/commit param just prints (nothing gets kept in the label repository). That makes labelprint usable as a "dumb" print API for other automation: it doesn’t need to know anything about the caller, and the caller doesn’t need any labelprint-specific client, just an HTTP form POST.

Example: randy/home-gitops has a workflow (.gitea/workflows/print-issues.yaml + scripts/print_issues.rb) that fetches its own open issues via the Gitea API and prints a summary on the Epson receipt printer — the Gitea-specific logic (fetching, formatting) lives entirely in that script, not here:

require 'net/http'

res = Net::HTTP.post_form(
  URI('http://rpi-printserver.hv.priesol.net/epson/raw'),
  'content' => "ESC E 0x01\nHello from CI\nESC E 0x00\nLF"
)

content uses labelprint’s mnemonic ESC/POS notation: ESC/GS/FS/LF/CR/HT/NUL as command names, 0xNN as a raw byte, anything else as literal text (CP852-encoded) — see the /epson page for the full reference and worked examples (alignment, bold, barcodes). POST /shipping/zpl works the same way but with a zpl form field taking plain ZPL instead.

Running

bundle install
bundle exec ruby app.rb

Requires config.json (see printer definitions inside) and a .session_secret file (random string, not committed).

Deployment

Runs as sinatra.service (systemd) on rpi-printserver.hv.priesol.net, under RVM (rvm default do bundle exec ruby app.rb — always uses whatever ruby is currently the RVM default, no manual bumping needed).

.gitea/workflows/deploy.yaml deploys on every push to main: SSH into rpi-printserver.hv.priesol.net, git pull, bundle install, restart the service.

Dependency updates

.gitea/workflows/renovate.yaml runs Renovate on a schedule (Monday 06:00 Europe/Bratislava, or manually) to open PRs for outdated gems and GitHub Actions. See the "Dependency Dashboard" issue for current status.