Neal Spangler

Work Endpoints

Paper in the feeder, PDF on the shared drive

I added scan-to-folder to an office printer that lacked it. A Python service detects paper in the feeder, starts the scan and saves the PDF to the shared drive without a computer login.

All-in-one inkjet printer
All-in-one inkjet printer Photo: Kskhh, CC BY-SA 4.0
0buttons, logins or apps needed to scan
13fixes from an adversarial review
3unattended test scans before it went live

The problem

The printer had a network-scanning interface, but a computer had to request each scan. Staff needed a way to load paper and get a file on the share without logging in or installing an app.

What I did

  • A Python service that watches the printer's eSCL status and scans every page when the feeder goes from empty to loaded.
  • Write PDFs under a temporary name, then rename the completed file into place on the share.
  • A local holding folder for scans made while the share is down, delivered automatically once it's back.
  • A sandboxed systemd service with restart limits and a watchdog heartbeat that continues through long scans. A health check on another machine alerts if it stops.
Walk-up scan pipeline A sandboxed service with a watchdog sees the printer's feeder go from empty to loaded, scans every page over eSCL, builds one PDF and renames it into place on the shared drive. If the share is down, the PDF is held locally and delivered later. sandboxed service with a watchdog Feeder loaded empty → loaded Scan pages over eSCL Build PDF all pages, one file Shared drive renamed into place Held locally if the share is down delivered later Load the feeder, get a PDF
The service waits for paper, scans, and holds files until the share can take them.

What I took from it

Scans reached the share after the first day. I spent the next day testing share outages, a hang during scanning and a failed install before leaving it for staff to use.

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