openstack/glance
Code Issues Proposed changes
cec64292df
glance/doc/source/architecture.rst
Nikhil Komawar 66335ba873 Remove references of s3 store driver 
As we are removing the s3 driver from source tree per change
I032b0fc16400cbd2112687d38e010128be699221 , it seems right to remove the
references of the same in the glance tree.

Updated here are files that referenced s3; these files include:

    * documentation files
    * documentation of the glance architecture (source and png files)
    * config help text
    * stores associated with location strategy
    * tests

UpgradeImpact

Change-Id: I680ee2baf39b49156d173e2ae108ae5d0221eca7
Depends-On: I032b0fc16400cbd2112687d38e010128be699221
Depends-On: I5d2da0611365b838f41285b64cdcfef9adf50e85
2016-08-11 12:32:48 -04:00

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Basic architecture

OpenStack Glance has a client-server architecture that provides a REST API to the user through which requests to the server can be performed.

A Glance Domain Controller manages the internal server operations that is divided into layers. Specific tasks are implemented by each layer.

All the file (Image data) operations are performed using glance_store library, which is responsible for interaction with external storage back ends and (or) local filesystem(s). The glance_store library provides a uniform interface to access the backend stores.

Glance uses a central database (Glance DB) that is shared amongst all the components in the system and is sql-based by default. Other types of database backends are somewhat supported and used by operators but are not extensively tested upstream.

Image 1. OpenStack Glance Architecture

Following components are present in the Glance architecture:

  • A client - any application that makes use of a Glance server.
  • REST API - Glance functionalities are exposed via REST.
  • Database Abstraction Layer (DAL) - an application programming interface

    (API) that unifies the communication between Glance and databases.

  • Glance Domain Controller - middleware that implements the main

    Glance functionalities such as authorization, notifications, policies, database connections.

  • Glance Store - used to organize interactions between Glance and various

    data stores.

  • Registry Layer - optional layer that is used to organise secure

    communication between the domain and the DAL by using a separate service.