Ceilometer is an OpenStack component that provides telemetry services for collecting and processing metering data in an OpenStack cloud environment. The ceilometer-agent-notification is one of the services provided by Ceilometer, responsible for receiving and processing metering notifications.
Here’s a detailed explanation of ceilometer-agent-notification:
- Purpose: The ceilometer-agent-notification service is designed to receive metering notifications from different OpenStack services and perform further processing on the received data. It acts as a central component for collecting and handling metering events within an OpenStack cloud environment.
- Notification System: OpenStack services generate metering notifications when specific events occur. For example, when an instance is created, deleted, or when resource utilization exceeds a threshold, these events trigger the generation of metering notifications. The ceilometer-agent-notification service acts as a consumer of these notifications.
- Notification Processing: Upon receiving metering notifications, the ceilometer-agent-notification service performs several tasks to process and store the collected data. These tasks include:
- Parsing: The service parses the received notifications to extract relevant information such as resource ID, timestamp, event type, and other metadata associated with the event.
- Data Transformation: The parsed data is transformed into a format suitable for storage and further analysis. This may involve converting data types, aggregating measurements, or applying filters.
- Storage: The transformed data is then stored in a backend database, such as a relational database or a time-series database. Ceilometer supports various database backends, including MongoDB, PostgreSQL, and MySQL.
- Data Enrichment: Additional information can be added to the collected data to enhance its context. For example, ceilometer-agent-notification can query the OpenStack Identity service (Keystone) to associate relevant project or user information with the collected data.
- Event Dispatching: After processing and storing the collected data, ceilometer-agent-notification can dispatch the processed data to other services or components within the OpenStack environment. For instance, it can forward the data to the Ceilometer API service or trigger alarms in the Aodh component for further actions.
- Configuration: The ceilometer-agent-notification service can be configured through its configuration file, typically located at
/etc/ceilometer/ceilometer.conf. This file allows administrators to specify the messaging transport mechanism (e.g., RabbitMQ, Kafka) and the appropriate authentication credentials for communicating with other OpenStack services. - Scalability and High Availability: To handle large-scale deployments, ceilometer-agent-notification can be deployed in a distributed manner across multiple nodes. This allows for load balancing and ensures high availability of the metering notification processing service. Additionally, message queue brokers like RabbitMQ or Kafka can be used to handle message distribution and ensure fault tolerance.
- Integration with other Ceilometer Components: ceilometer-agent-notification works closely with other Ceilometer components to provide a comprehensive metering solution. It interacts with the Ceilometer Collector service, which aggregates metering data from multiple agents for further processing and analysis. The Ceilometer API service provides a RESTful API for querying and retrieving the collected metering data.
In summary, the ceilometer-agent-notification is a component of the Ceilometer project in OpenStack. It receives metering notifications from various OpenStack services, processes and transforms the data, stores it in a backend database, and dispatches it to other components or services for further analysis and actions. It plays a crucial role in providing telemetry and metering capabilities within an OpenStack cloud environment.