Show Patroni cluster status, topology and history

Command

# Members, roles, state, timeline and lag (MB):
patronictl -c /etc/patroni/patroni.yml list <cluster>
# Extended info (pending restart, tags) + timestamp, refresh every 5 s:
patronictl -c /etc/patroni/patroni.yml list <cluster> -e -t -w 5
# Leader -> replica tree (including cascading replicas):
patronictl -c /etc/patroni/patroni.yml topology <cluster>
# Past failovers/switchovers (timeline, LSN, reason, time):
patronictl -c /etc/patroni/patroni.yml history <cluster>

What it does

Shows Patroni's cluster view from the DCS: leader/replica roles, member state (running/streaming), timeline, replication lag and pending restarts; history lists timeline changes with the LSN at which they happened.

When to use it

Before and after every switchover/failover/maintenance, and as the first diagnostic step when an alert fires.

Caution

The output reflects what is stored in the DCS; if the DCS is unreachable the command fails or may show stale data. Do not start a switchover before confirming all members are on the same timeline and Lag in MB is below maximum_lag_on_failover.