Bootstrapping a standby cluster using pgBackRest

[l2dy]

Pigsty sets create_replica_methods key in standby_cluster section to basebackup only. Can pgbackrest be supported too?

pigsty/roles/pgsql/templates/oltp.yml

Lines 215 to 217 in c4ddba7

	create_replica_methods:
	- basebackup
	{% endif %}

Implementation notes

1. A standby cluster needs to restore from the upstream cluster's stanza during its bootstrap, which is different from {{ pg_cluster }} used by cascade replicas replicating from standby leader.
2. restore_command of the standby leader should bet set to pgbackrest archive-get with the upstream cluster's stanza, in case some WAL segments on the upstream primary have been recycled during restore and could not be received via streaming replication.