The purpose of this spec is to add support for the OpenStack Gnocchi program to OpenStack-Ansible. This would allow the deployment of Gnocchi along with the core OpenStack components using OpenStack-Ansible.
Blueprint - Gnocchi deployment on OpenStack-Ansible:
Presently, while deploying OpenStack using OpenStack-Ansible only the core OpenStack components get deployed. The deployment of other components (eg: Gnocchi) via Ansible playbooks is not supported yet and to use this component’s services, they need to be deployed manually.
Gnocchi is a multi-tenant timeseries, metrics, and resources database. It is designed to store metrics at a very large scale and to allow the retrieval of those metrics quickly and efficiently, each through an HTTP REST interface. Additionally, Gnocchi is designed to stand as a replacement storage engine for metrics processed through Ceilometer, relying on a more performant storage format.
This spec proposes to allow deployment and management of this service with a versatile configuration capable of scaling in a way that conforms to both the best practices from the Gnocchi and Telemetry communities as well as with those of the OpenStack-Ansible community.
This involves adding support for the Gnocchi services, and the Gnocchi client into the appropriate hosts and containers. It also involves the optional configuration of Ceilometer to use Gnocchi in lieu of the currently supported MongoDB storage solution.
The proposed changes include:
Test playbooks will be placed in the openstack-ansible-os_gnocchi repository for functional testing purposes. Some changes are anticipated within the openstack-ansible-os_ceilometer role to configure deployment options needed for an optional integration where Ceilometer uses Gnocchi as it’s storage engine. Further a playbook, necessary group_vars and env and conf profiles would be provided for the openstack-ansible repository to complete the integration.
None. While an operator who had previously deployed Ceilometer might be interested in deploying Gnocchi, there is no migration model for exporting data from Ceilometer internal storage to Gnocchi storage. The Gnocchi role and any supporting changes to the Ceilometer role would make the transition as simple as running the associated playbooks.
The underlying storage used for Gnocchi would experience higher traffic, which might require a deployer to account for that additional traffic through additional tuning.
No other performance impacts are expected.
OpenStack users would be able to make use of Gnocchi as a multi-tenant high volume timeseries data store when deployers use the role and associated playbook to deploy Gnocchi.
This work provides an optional role for use in the OpenStack-Ansible tooling for use in their environments.
Some conditionals may be introduced into the Ceilometer role to facilitate the clean deployment of Gnocchi as a storage engine for Ceilometer. All other changes would be self-contained or limited to the introduction of new variables and a playbook which should present little to no additional cognitive load for developers.
Only a MySQL-compatible RDBMS is proposed for the Gnocchi index. Only filesystem, Ceph, and Swift storage engines are proposed. All of these are currently available within OpenStack-Ansible.
No support is proposed at this time for use of Graffana as a dashboard or the use of the statsd service endpoints for Gnocchi. In this way we avoid introducing any new dependencies.
- Add support for running Gnocchi services (api and metricd) with basic convergence testing.
- Add an Ansible module to leverage gnocchiclient, which is the command line interface tool for using and managing Gnocchi.
- Introduce a playbook for deploying Gnocchi with OpenStack-Ansible.
- Add support for Gnocchi as an optional storage engine for Ceilometer.
- Add a full scenario test (described below) to ensure successful integration of Gnocchi.
- Add documentation to the role, and possibly general documentation to the install guide for deploying Gnocchi with each of the various supported storage engines.
In an environment where the role is integration tested through the openstack-ansible repository in one monolithic stack, the additional effort of deploying this additional project could add as much as a few minutes to gate testing. That is not desirable.
To preclude the need for that additional step in the main gate, a longer scenario test is proposed for inclusion in the openstack-ansible-os_gnocchi role, to integrate with Keystone, Nova, Cinder, Glance, Neutron, Ceilometer, and Gnocchi with metrics collection enabled and with Nova being exercised to ensure metering data propagates through the OpenStack environment.
This can then be verified through the use of the Ansible module for gnocchiclient by querying for the expected measures.
Role-specific documentation describing the configuration of Gnocchi will be required.