The associated bug is due to a change introduced in commit d55dcde
which was to ensure that the correct password update is used for
different versions of mysql (pre and post 5.7.5). However, this change
has broken the nagios user creation due to not setting the password.
This patch creates the nagios user and passord at the same time. The
updating of the password is only done if the account already exists.
The change also corrects the nagios password store in leader-settings to
the 'mysql-nagios.passwd' key instead of 'nagios-password'. This was an
unfortuante error when the nagios change password was introduced. The
charm detects if the 'nagios-password' key is used on charm-upgrade and
moves it to 'mysql-nagios.passwd'. This enables the key to work with
the standard MySQLHelper functions.
Finally, the ALTER command (on percona) doesn't update non-InnoDB tables
and thus needs to be run for each unit when the nagios password is
changed via the action. The changes in percona_utils.py enable this to
happen.
Whilst the change looks large it ONLY affects the nagios password parts
of the charm.
The related bug is a tracking bug to serve as a reminder to fix this in
charm-helpers and this charm (i.e. make the charm-helpers code work to
change a password for any user other than root, and then enable this
charm to use that code).
Change-Id: Ibc751bef7b4654ebffdf843c556b193373e6e80c
Related-Bug: #1925377
Closes-Bug: #1925042
432c3f0be4