It could take up to 10 seconds to create replication slot.
In addition to that when replica fails to connect to the master via
streaming replication it doesn't retry immediately, but with some
timeout (5 seconds). 10 + 5 == 15 what causes replication check
scenarios fail.
It was shutdown correctly and I expected such 'join' working, but it was
not, because new leader didn't had enough time to catch up with the
master before promote.
The actual amount of time to establish the master and the replication
after the scheduled failover seems sufficient (15 seconds with the
failover in 10 seconds), but occasionally leads to test failures.
This is unlikely the test issue and should be investigated inside
the patroni.
Add an ability to specify the origin and the destination for
the replication works clause. Use this ability in the API
promotion test to ensure the replication from the former
replica to the former master.
Alexander Kukushkin