The Telemetry service uses an agent-based architecture. Several modules combine their responsibilities to collect data, store samples in a database, or provide an API service for handling incoming requests.
The Telemetry service is built from the following agents and services:
computenamespace polls the local hypervisor to acquire performance data of local instances. The
centralnamespace polls the public RESTful APIs of other OpenStack services such as Compute service and Image service. The
ipminamespace polls the local node with IPMI support, in order to acquire IPMI sensor data and Intel Node Manager datahost-level information.
Consumes AMQP notifications from the agents, then dispatches these data to the appropriate data store.
ceilometer-pollingservice provides polling support on any namespace but many distributions continue to provide namespace-scoped agents:
ceilometer-collectorare no longer supported since the Ocata release. Storage and API are provided by gnocchi, aodh, and panko services.
Except for the
ceilometer-polling agents polling the
ipmi namespaces, all the other services are placed on one or more
The Telemetry architecture highly depends on the AMQP service both for consuming notifications coming from OpenStack services and internal communication.
The other key external component of Telemetry is the database, where events, samples, alarm definitions, and alarms are stored. Each of the data models have their own storage service and each support various back ends.
The list of supported base back ends for measurements:
The list of supported base back ends for alarms:
The list of supported base back ends for events:
The Telemetry service collects information about the virtual machines, which requires close connection to the hypervisor that runs on the compute hosts.
The following is a list of supported hypervisors.
Telemetry is able to retrieve information from OpenStack Networking and external networking services:
This service of OpenStack uses OpenStack Identity for authenticating and authorizing users. The required configuration options are listed in the Telemetry section in the OpenStack Configuration Reference. Alternatively, gnocchi can be configured without authentication to minimize overhead.
The system uses two roles:
non-admin. The authorization
happens before processing each API request. The amount of returned data
depends on the role the requestor owns.
The creation of alarm definitions also highly depends on the role of the user, who initiated the action. Further details about Alarms handling can be found in this guide.