Writing
Thinking out loud on ML systems, backend architecture, and building software that behaves under pressure.
The Booking That Took Itself: Solving Double-Booking with a Sentinel Lock
SELECT FOR UPDATE prevents two people from booking the same slot — except when the slot is the first one of the day. Here's the edge case, and the one-line fix.
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The Firewall Rule That Wasn't: Docker, ufw, and a Silent Port Leak
ufw was configured correctly. The port was still open to the internet. Here's the iptables ordering issue that caused it, and how to actually close it.
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