What is Gnocchi?

Gnocchi is a service for managing a set of resources and storing metrics about them. It allows its users to create resources (servers, images, volumes…) with properties (name, URL, flavors…) and to associate those resources with metrics (CPU usage, bandwidth…) that are going to metered.

The point of Gnocchi is to provide this service and its features in a scalable and resilient way. Its functionalities are exposed over an HTTP REST API.

A Brief History of Gnocchi

The Gnocchi project was started in 2014 as a spin-off of the OpenStack Ceilometer project to address the performance issues that Ceilometer encountered while using standard databases as a storage backends for metrics. More information are available on Julien’s blog post on Gnocchi.

Project Architecture

Gnocchi is built around 2 main components: a storage driver and an indexer driver. The REST API exposed to the user manipulates both these drivers to provide all the features that are needed to provide correct infrastructure measurement.

The storage is responsible for storing measures of created metrics. It receives timestamps and values and computes aggregations according to the defined archive policies.

The indexer is responsible for storing the index of all resources, along with their types and their properties. Gnocchi only knows resource types from the OpenStack project, but also provides a generic type so you can create basic resources and handle the resource properties yourself. The indexer is also responsible for linking resources with metrics.