Ceilometer is an OpenStack telemetry (observability/monitoring) service that collects, normalizes, and publishes measurements about the usage and performance of OpenStack cloud resources for metering, billing, and monitoring use cases.

Telemetry collection and aggregation for OpenStack services (observability/monitoring)
Event and resource usage metering across compute, storage, and networking (usage metering/billing support)
Pluggable collection agents and pipelines for polling and notification-based metrics (metrics pipeline framework)
Integration with OpenStack services such as Nova, Cinder, Neutron, and others for resource statistics (cloud infrastructure monitoring)
Data publishing to external storage and processing backends via configurable publishers (data export/integration)

More About Ceilometer

Ceilometer is the telemetry component in the OpenStack cloud platform, designed to collect, normalize, and publish measurements about the usage and performance of OpenStack-managed resources. Its primary purpose is to enable operators and service providers to support use cases such as billing, chargeback, capacity planning, and operational monitoring by providing a uniform telemetry interface across the OpenStack ecosystem (cloud observability/monitoring).

The project focuses on gathering metering data from multiple OpenStack services and resources, including compute instances, block storage volumes, networking elements, and other service-level events (usage metering). Ceilometer supports both polling-based and notification-based data collection through agents that interact with OpenStack APIs, message buses, and service-specific instrumentation. These agents capture metrics and events such as resource lifecycle changes, bandwidth usage, Central Processing Unit (CPU) and memory utilization, and storage operations where supported by integrated services.

Ceilometer uses a configurable pipeline architecture that defines how collected samples and events are transformed, filtered, and dispatched (metrics pipeline framework). Pipelines can publish data to various backends, including time-series databases or other external storage systems, through publisher plugins. This design allows operators to integrate Ceilometer telemetry with existing monitoring, billing, or analytics platforms by selecting appropriate publishers or developing custom ones (data export/integration).

Within enterprise and institutional OpenStack deployments, Ceilometer functions as a central telemetry service that works alongside other OpenStack components. It consumes notifications from services such as Nova for compute, Cinder for block storage, and Neutron for networking, among others, using the OpenStack messaging infrastructure. By standardizing how measurements are represented and accessed, Ceilometer enables consistent telemetry across heterogeneous OpenStack services and regions (cloud management tooling).

From an architectural perspective, Ceilometer typically runs as a set of distributed agents and services deployed within an OpenStack control plane. These include polling agents that query APIs at intervals, notification agents that subscribe to message queues, and services responsible for processing and publishing measurements. Ceilometer exposes telemetry data through OpenStack APIs, which can be used by higher-level services and dashboards, or by external systems that consume metering data for reporting and automation (API-based integration).

For enterprises, Ceilometer provides a telemetry foundation for cost allocation, capacity management, Service Level Agreement (SLA) monitoring, and operational insight into OpenStack-based private or public clouds. In a technical directory, Ceilometer is categorized under cloud telemetry, metering, and observability within the OpenStack and OpenInfra ecosystem, functioning as the telemetry layer that feeds data to billing, monitoring, and analytics solutions.