Aodh-Expirer is a component of the OpenStack Telemetry (Ceilometer) project, specifically designed to handle the expiration of old alarm data in the Aodh alarm service. OpenStack is an open-source cloud computing platform that provides various services and components for building and managing cloud infrastructure.
The Aodh project within OpenStack is responsible for handling alarms and notifications. Alarms in Aodh monitor predefined events or conditions in an OpenStack deployment, and when triggered, they can take specific actions such as sending notifications or executing automated tasks. Aodh-Expirer is a service that runs periodically to clean up expired alarm data in the Aodh database. When an alarm is created, it can be configured with a specific time-to-live (TTL) value. Once the TTL period has elapsed, the alarm is considered expired and can be removed from the system to free up resources and maintain a clean alarm database.
Here’s an overview of how Aodh-Expirer works:
- Configuration: Aodh-Expirer requires appropriate configuration settings to connect to the Aodh database and determine the expiration policy. This includes parameters like the frequency of the expirer process, the time interval to query for expired alarms, and the TTL value for alarms.
- Scheduled Execution: Aodh-Expirer is typically run as a periodic task or a cron job on the OpenStack controller node. It executes at regular intervals, such as every hour or every day, as per the configured frequency.
- Alarm Expiration: During each execution, Aodh-Expirer queries the Aodh database for alarms that have exceeded their TTL. It identifies and selects the alarms that are due for expiration.
- Alarm Removal: Once the expired alarms are identified, Aodh-Expirer removes them from the Aodh database. This process ensures that old and unnecessary alarm data is deleted, reducing the storage requirements and improving overall system performance.
- Logging and Reporting: Aodh-Expirer generates logs and reports the details of its execution. These logs provide information about the expired alarms, the number of alarms removed, and any encountered errors or exceptions during the expiration process.
By running Aodh-Expirer regularly, administrators can ensure that the alarm database remains up-to-date and contains relevant information. It helps prevent the accumulation of outdated alarm data, which can impact system performance and consume unnecessary resources.