Ceilometer, Aodh, and Gnocchi - Telemetry

Ceilometer provides a metering service in OpenStack. In a shared, multi-tenant environment such as OpenStack, metering resource utilization is of prime importance.

Ceilometer collects data associated with resources. Resources can be any entity in the OpenStack cloud such as VMs, disks, networks, routers, and so on. Resources are associated with meters. The utilization data is stored in the form of samples in units defined by the associated meter. Ceilometer has an inbuilt summarization capability.

Ceilometer allows data collection from various sources, such as the message bus, polling resources, centralized agents, and so on.

As an additional design change in the Telemetry service in OpenStack since the Liberty release, the Alarming service has been decoupled from the Ceilometer project to make use of a new incubated project code-named Aodh. The Telemetry Alarming service will be dedicated to managing alarms and triggering them based on collected metering and scheduled events

More Telemetry service enhancements have been proposed to adopt a Time Series Database as a Service project code-named Gnoochi. This architectural change will tackle the challenge of metrics and event storage at scale in the OpenStack Telemetry service and improve its performance.

Telemetry and system monitoring are covered in more detail in Chapter 10, Monitoring and Troubleshooting - Running a Healthy OpenStack Cluster.