Ceilometer

Ceilometer: The Telemetry Component in OpenStack

Ceilometer is a data collection service within the OpenStack Telemetry project. It provides the ability to collect, normalize, and transform data across all OpenStack components. This data can be used for billing, resource tracking, and alarming purposes.

How Ceilometer Works

Ceilometer operates through several key components and processes:

Data Collection:
- Polling: Ceilometer retrieves information directly from the hypervisor or by using the APIs of other OpenStack services.
- Notifications: It processes notifications from other OpenStack services by consuming messages from the message queue system.
Data Processing:
- Notification Agent: Consumes notifications from the message bus and transforms them into events and measurement samples.
- Polling Agent: Periodically polls the infrastructure to collect resource utilization statistics.
Data Storage:
- Collected data is stored in supported databases, which can be queried for generating reports and alarms.
Data Publishing:
- Ceilometer publishes collected data to various targets, including data stores and message queues, for further processing and analysis.

Practical Analogy

Think of Ceilometer as a utility meter reader in a smart city:

Polling Agent: The meter reader who periodically checks the electricity, water, and gas meters at each house.
Notification Agent: The smart meters that automatically send usage data to the central system whenever there is significant activity.
Data Storage: The central database where all the collected meter readings are stored.
Data Publishing: The billing department that uses the stored data to generate utility bills and send alerts to residents about their usage.

Practical Use-Cases

Billing: Ceilometer can be used to track resource usage and generate billing reports for cloud tenants based on their consumption.
Resource Tracking: It helps administrators monitor the utilization of cloud resources, such as CPU, memory, and storage, to ensure efficient usage and capacity planning.
Alarming: Ceilometer can trigger alarms based on predefined thresholds, allowing administrators to respond to potential issues, such as resource overutilization or failures.
Performance Monitoring: It provides detailed insights into the performance of cloud infrastructure, helping to identify bottlenecks and optimize resource allocation.
Auto-Scaling: Ceilometer data can be used to automatically scale cloud resources up or down based on demand, ensuring optimal performance and cost-efficiency.