Fix 502 Bad Gateway in Nginx

SQL Lens

Run this query locally to surface offenders.

SELECT time_local, request, status FROM logs WHERE status = 502 ORDER BY time_local DESC LIMIT 50

Playbook

1. Verify upstream pods/processes are healthy and accepting traffic.
2. Check keepalive/timeout alignment between Nginx and upstream.
3. Inspect error.log for upstream prematurely closed connection entries.