This patchset aims to add HA Clustering support for Postgres. HA Clustering
provides automatic failover in the event of the database going down in addition
to keeping replicas of the database for rebuilding in the event of a node
going down. To achieve this clustering we use
[Patroni](https://github.com/zalando/patroni) which offers HA clustering
support for Postgres.
Patroni is a daemon that runs in the background and keeps track of which
node in your cluster is currently the leader node and routes all traffic
on the Postgresql endpoint to that node. If the leader node goes down,
Patroni holds an election to chose a new leader and updates the endpoint
to route traffic accordingly. All communication between nodes is done by
a Patroni created endpoint, seperate from the externally facing Postgres
endpoint.
Note that, although the postgresql helm chart can be upgraded from
non-patroni to patroni clustering, the previous `postgresql`
endpoints object (which is not directly managed by helm) must be
deleted via an out-of-band mechanism so that it may be replaced by the
patroni-managed endpoints. If Postgres itself is leveraged for the
deployment process, this must be done with careful timing. Note that
the old endpoints had a port named "db", and the new endpoints has
a port named "postgresql".
- Picking up patchset: https://review.openstack.org/#/c/591663
Co-authored-by: Tony Sorrentino <as1413@att.com>
Co-authored-by: Randeep Jalli <rj2083@att.com>
Co-authored-by: Pete Birley <pete@port.direct>
Co-authored-by: Matt McEuen <mm9745@att.com>
Change-Id: I721b745017dc1ea7ae05dfd9f8d5dd08d0965985
9efb353b83