[Ceilometer] Set parameter disable_non_metric_meters to True by default

[Vitaly Gusev]

As Ceilometer has expanded to capture more notifications from the OpenStack message ecosystem, the number of samples it generates grows even faster as many samples are derived from a single notification or polling request.

The "Existence of xyz" meters we store in our samples database represents a significant portion of the data we store. These meters however offer no useful measurement value and it's true value is to capture the state of the resource at a given time -- a value that is also available in the meters generated alongside the existence meters. Additionally, the volume=1 value is very confusing to consumers of data as for a while, Horizon used that value as the total number of values and often users would wonder why there was always 1 record of an instance, network, port, etc.

As we move to a more time-series focused storage for samples, the "volume=1" meters we collect has not just an impact on storage size, but also the overhead of rolling up and computing statistics on something as trivial and meaningless as the constant 1. Additionally, the rollup of samples will diminish the value of said meters as valid auditable datapoints.

At a high-level, Samples are the children of Events. Samples are a derived subset of an Event. Because of that, the Samples we create should capture an explicit datapoint of interest from an Event and not just be a shadow of an Event.

So that's why need to set parameter disable_non_metric_meters to True by default in ceilometer.conf file.

Upstream blueprint https://blueprints.launchpad.net/ceilometer/+spec/deprecate-existence-meters

[Ivan Berezovskiy (iberezovskiy)]

Upstream patch is https://review.openstack.org/#/c/253451/

[Vitaly Gusev (vgusev)]

Move this bug to Invalid. We will use disable_non_metric_meters=False by default and deprecate some meters in pipeline files. See https://bugs.launchpad.net/mos/+bug/1524682 .