Scheduled failover allows scheduling of a failover in the future. It does this by writing
a failover key in the DCS which contains the scheduled failover time.
The reason to allow a scheduled failover, is that it does not require one to use a
scheduler (e.g. cron) to schedule such a failover. One of the issues with using
a scheduler is that it may need to authenticate itself. With scheduled failover the authentication
takes place during the scheduling, not during the actual failover.
To allow the time of failover to be expressed, the failover key has changed its format; the old format however
can still be used. The new format expects the failover key to be a json-document with relevant
keys set. We need the timestamp specified to be time zone aware and to be expressed unambigiously, e.g. ISO 8601.
Do not try to create replication slots on the replica for the
member that wants to replicate from it if the member's currently
holds the master role.
Remove a debug message.
Master shouldn't keep a replication slot for the members that
replicate from other members instead of the master (replicatefrom).
Otherwise, the master will keep collecting WAL segments that won't
be requested ever. Of course, if the destination of replicatefrom
is not part of the cluster, master should create the slot.
The replication method should have no_master flag set and
support getting the base backup from some external storage
(i.e. S3). At the moment we only support initialization of
replicas in the already existing cluster when no master is
present, since there is no 'one fits all' way to decide whether
to run initidb or wait for the replica data storage to become
available when dealing with the new cluster.
Rename the follow_the_leader to just follow, since the node to
be followed is not necessary a leader anymore. Extend the code
that manages replication slots to the non-master nodes if they
are mentioned in at least one replicatefrom tag.
Add the 3rd configuration in order to be able to run cascading
replicas.
Our current master branch doesn't pass the code coverage test, due to behaviour changes
in upstream python-etcd.
As a bandaid, fix the version for now.
Reference build fail:
https://travis-ci.org/zalando/patroni/jobs/98470121
Call normal follow the leader method from HA even during recovery.
This provides a single place that changes recovery.conf, making
it easier to plug in a cascading replica in the future.
Remove an obsolete demote function from PostreSQL module, modified
the tests.
Feike Steenbergen