my.jorgecuadros.com serves customer balances from the Oracle VPS replica.
A replica whose SQL thread has stopped does not error — it keeps answering,
with data frozen at the moment it stopped — so nothing on the customer site
looks wrong and the only signal is a customer complaining about a stale
balance. This puts the failure somewhere a human sees it.
Deliberately does not trust the two fields an operator reaches for first.
Replica_IO_Running reports Yes while the SQL thread is stopped, because the
network thread keeps downloading binlog it will never apply; verified by
stopping SQL_THREAD and watching IO stay Yes. Seconds_Behind_Source reads
NULL whenever EITHER thread is down, so the card renders "sin dato" rather
than "0 s" — showing zero there would report an outage as perfect health.
The problem string is resolved most-specific-first for the same reason.
Shells out to the mysql client because the API has no MySQL driver and the
image already ships one. --ssl is required (the replica sets
require_secure_transport); --ssl-verify-server-cert=0 is deliberate and is
NOT the trade-off the website makes: this hop never leaves Tailscale and the
replica's firewall admits only this host, so WireGuard authenticates the
peer, whereas the DreamHost leg crosses the public internet and pins the CA.
The account behind it holds REPLICATION CLIENT and nothing else — it cannot
read a single row. REPLICA_DB_* unset is a supported state and renders "no
configurada", which is correct in dev and before cutover.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
rmancinasandClaude Opus 5
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