Telemetry Alarming service overview
The Telemetry Alarming services trigger alarms when the collected metering
or event data break the defined rules.
The Telemetry Alarming service consists of the following components:
- An API server (
aodh-api) 
- Runs on one or more central management servers to provide access
to the alarm information stored in the data store.
 
- An alarm evaluator (
aodh-evaluator) 
- Runs on one or more central management servers to determine when
alarms fire due to the associated statistic trend crossing a
threshold over a sliding time window.
 
- A notification listener (
aodh-listener) 
- Runs on a central management server and determines when to fire alarms.
The alarms are generated based on defined rules against events, which are
captured by the Telemetry Data Collection service’s notification agents.
 
- An alarm notifier (
aodh-notifier) 
- Runs on one or more central management servers to allow alarms to be
set based on the threshold evaluation for a collection of samples.
 
These services communicate by using the OpenStack messaging bus.