glance/doc/source/gettingstarted.rst

Quick Guide to Getting Started with Glance

Glance is a server that provides the following services:

• Ability to store and retrieve virtual machine images
• Ability to store and retrieve metadata about these virtual machine images
• FUTURE: Convert a virtual machine image from one format to another
• FUTURE: Help caching proxies such as Varnish or Squid cache machine images

Communication with Glance occurs via a REST-like HTTP interface.

However, Glance includes a Client <client> class that makes working with Glance easy and straightforward.

In the Cactus release, there will be also command-line tools for interacting with Glance.

Overview of Glance Architecture

There are two main parts to Glance's architecture:

• Glance API server
• Glance Registry server(s)

Glance API Server

The API server is the main interface for Glance. It routes requests from clients to registries of image metadata and to its backend stores, which are the mechanisms by which Glance actually saves incoming virtual machine images.

The backend stores that Glance can work with are as follows:

• Swift

  Swift is the highly-available object storage project in OpenStack. More information can be found about Swift here.

• Filesystem

  The default backend that Glance uses to store virtual machine images is the filesystem backend. This simple backend writes image files to the local filesystem.

• S3

  This backend allows Glance to store virtual machine images in Amazon's S3 service.

• HTTP

  Glance can read virtual machine images that are available via HTTP somewhere on the Internet. This store is readonly

Glance Registry Servers

Glance registry servers are servers that conform to the Glance Registry API. Glance ships with a reference implementation of a registry server that complies with this API (glance-registry).

For more details on Glance's architecture see here <architecture>. For more information on what a Glance registry server is, see here <registries>.