Split brain writes after failover
At 02:14 your Postgres primary (managed via Patroni + etcd) became unreachable and Patroni promoted a standby. Writes resumed within 40s. At 02:30 the old primary came back online and your monitoring now shows two nodes both accepting writes for ~6 minutes, and a few duplicate-key and constraint-violation errors are appearing in app logs. The network team reports a transient partition between availability zones during the incident. Walk through how you triage, contain, and recover, and how you prevent recurrence.
What a strong answer looks like
Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.
0:00 of about 40 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.