Vol. 1 · 5 issues Maimul’s notebook

Today I Learned

All the bugs that are fit to print

Latest: Monday, 26 October 2026 Home lab · cloud · infrastructure Free to read
No. 005 · deploys · git · bash · zsh

The Deploy That Went Green and Shipped Nothing

My home server's deploy failed at step one, and every step after it reported success. Here's how a failure goes missing in a deploy chain, and a copy-paste script that refuses to call nothing a success.

What you’ll learn
  • How `git pull` on a server can fail while every step after it succeeds, and how to spot it.
  • How an exit status gets lost in a pipe, and what `set -euo pipefail` changes.
  • A copy-paste deploy script that stops when the pull fails, HEAD is wrong, the image didn't change or the pods run something else.
  • Two more silent failures: zsh and an unquoted `$list`, and a misleading backup error.
Monday, 26 October 2026 · Read the issue →

Earlier editions

  1. No. 004 · 24 Oct 2026

    The Guard That Couldn’t Read, So It Waved the Commit Through

    My AI coding agent was only allowed to commit code once the code passed my checks. One night the checks failed, the agent committed anyway, and the guard I'd built to stop exactly that did nothing. Here's why, in plain words, and the rule that fixes it.

    Related to: claude-code · git-hooks · ai-coding-agents · ci
  2. No. 003 · 21 Oct 2026

    Every Test Passed. Production Returned 500.

    My test suite was green, my smoke test was green, and a photo upload in a FastAPI app I work on had never worked. Here's the Python behaviour that hid it, the test that now catches it, and why fixing the bug still didn't fix the feature.

    Related to: python · imports · fastapi · testing
  3. No. 002 · 19 Oct 2026

    The Case of the Printer Nobody Could Reach

    My iPhone could see my home printer, but it hadn't printed a page in 127 days. Here's how I tracked down why, what finally fixed it, and how to check your own setup when AirPrint goes quiet.

    Related to: bonjour · mdns · avahi · airprint
  4. No. 001 · 19 Oct 2026

    AirPrint for a Printer That Never Had It

    My Epson L3250 doesn't support AirPrint, so my iPhone can't see it. One small container on my Synology NAS fixes that. Here's how it works, and how to set it up for your own printer.

    Related to: airprint · cups · avahi · bonjour