Comment 5 for bug 1850945

Reviewed: https://review.opendev.org/701343
Committed: https://git.openstack.org/cgit/openstack/kolla-ansible/commit/?id=1b89068bb6092ea2d3bdac3d0282b0df1cb6e2ce
Submitter: Zuul
Branch: stable/stein

commit 1b89068bb6092ea2d3bdac3d0282b0df1cb6e2ce
Author: Mark Goddard <email address hidden>
Date: Fri Nov 1 15:17:48 2019 +0000

    Enable load balancing to Galera nodes in Donor state

    We use the wsrep_notify.sh script to notify changes in Galera cluster
    membership to haproxy. When xtrabackup was used for the state transfer,
    nodes in the Donor state would be included in the backend pool. However,
    since the switch to mariabackup in the Stein cycle, we now remove nodes
    in the Donor state from the backend pool.

    This change ensures that nodes in the Donor state are included in the
    backend pool when the SST method is either xtrabackup or mariabackup.

    https://galeracluster.com/library/documentation/mysql-wsrep-options.html#wsrep-notify-cmd

    Change-Id: Ide4301779a0d221ae5d4dbdd4873fb8a40eb7297
    Co-authored-by: Radosław Piliszek <email address hidden>
    Closes-Bug: #1850945
    (cherry picked from commit f6e8478b6112a6a4820ce8ed867a5a05b16d9bf0)