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Senlin Architecture
===================

Senlin is a service to create and manage clusters of homogeneous resources in
an OpenStack cloud. Senlin provides an OpenStack-native ReST API.


--------------------
Detailed Description
--------------------

What is the purpose of the project and vision for it?

*Senlin provides a clustering service for OpenStack that manages a collection
of nodes that are of the same type.*

Describe the relevance of the project to other OpenStack projects and the
OpenStack mission to provide a ubiquitous cloud computing platform:

*The Senlin service aggregates resources exposed by other components of
OpenStack into a cluster. Such a cluster can be associated with different
policies that can be checked/enforced at varying enforcement levels. Through
service APIs, a user can dynamically add nodes to and remove nodes from a
cluster, attach and detach policies, such as creation policy, deletion policy,
load-balancing policy, scaling policy, health checking policy etc. Through
integration with other OpenStack projects, users will be enabled to manage
deployments and orchestrations large scale resource pools much easier.*
*Currently no other clustering service exists for OpenStack. The developers
believe cloud developers have a strong desire to create and operate resource
clusters on OpenStack deployments. The Heat project provides a preliminary
support to resource groups but Heat developers have achieved a consensus that
such kind of a service should stand on its own feet.*

---------------
Senlin Services
---------------

The developers are focusing on creating an OpenStack style project using
OpenStack design tenets, implemented in Python. We have started with a close
interaction with Heat project.

As the developers have only started development in December 2014, the 
architecture is evolving rapidly.

senlin
------

The senlin tool is a CLI which communicates with the senlin-api to manage
clusters, nodes, profiles, policies and events. End developers could also use
the Senlin REST API directly.


senlin-api
----------

The senlin-api component provides an OpenStack-native REST API that processes
API requests by sending them to the senlin-engine over RPC.


senlin-engine
-------------

The senlin engine's main responsibility is to orchestrate the clusters, nodes,
profiles and policies.