Horizon is a modular Django web application that provides an end user and administrator interface to OpenStack services.
As with most web applications, the architecture is fairly simple:
Horizon is usually deployed via mod_wsgi in Apache. The code itself is separated into a reusable python module with most of the logic (interactions with various OpenStack APIs) and presentation (to make it easily customizable for different sites).
A database (configurable as to which one). As it relies mostly on the other services for data, it stores very little data of its own.
From a network architecture point of view, this service will need to be customer accessible as well as be able to talk to each service's public APIs. If you wish to use the administrator functionality (i.e. for other services), it will also need connectivity to their Admin API endpoints (which should be non-customer accessible).
