In order to fix bug#1756928 the whole cluster buildup process needed to
be redesigned. The assumptions about what is_bootstrapped and clustered
meant and when to restart on configuration changed needed to be
re-evaluated.
The timing of restarts needed to be protected to avoid collisions.
Only bootstrapped hosts should go in to the
wsrep_cluster_address=gcomm:// setting. Adding or removing units should
be handled gracefully. Starting with a single unit and expanding to a
cluster must work.
This change guarantees mysqld is restarted when the configuration file
changes and meets all the above requirements. As a consequence of the redesign,
the workload status now more accurately reflects the state of the unit.
Charm-helpers sync to bring in distributed_wait fix.
Closes-Bug: #1756308
Closes-Bug: #1756928
Change-Id: I0742e6889b32201806cec6a0b5835e11a8027567
Liam Young