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Despite our conversation in the meeting yesterday[1] I still remain a
bit confused about the upgrade path from alarming-in-ceilometer to
alarming provided by aodh and the availability of the older code in
released liberty.

Much of my confusion can probably be resolved by knowing the answer to
this question:

If someone installs aodh on a machine that already has ceilometer on it
and turns off ceilometer-alarm-notifier and ceilometer-alarm-evaluator
(in favor of aodh-notifier and aodh-evaluator) will they be able to run
those aodh services against their existing ceilometer.conf files[2]?

What if they were, in ceilometer, using specific config for their
alarming database (alarm_connection). Can aodh "see" and use this
config option?

Or will they need to copy and modify the existing conf files to allow
them to carry on using their existing database config?

I know that I can go try some of this in a devstack, but that's not
really the point of the question. The point is: What are we expecting
existing deployments to do?

I had assumed that the reason for keeping alarming in ceilometer for
the liberty release was to allow a deployment to upgrade to Liberty
across the project suites without having to go through modifying
alarming config and managing an alarming migration in the same step.
That migration ought to be pretty minor (tweak a config here and
there) but unless the answer to my first question is "yes" it has some
significance.

[1] http://eavesdrop.openstack.org/meetings/ceilometer/2015/ceilometer.2015-08-06-15.01.log.html#l-110

[2] directly as in aodh-notifier --config-file /etc/ceilometer/ceilometer.conf

-- 
Chris Dent tw:@anticdent freenode:cdent
https://tank.peermore.com/tanks/cdent