Commit f449f606 authored by Christos Stavrakakis's avatar Christos Stavrakakis

Update docs about Cyclades-Ganeti communication

parent 0b148e50
......@@ -230,6 +230,38 @@ Image Overview
Architecture
------------
Asynchronous communication with Ganeti backends
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Synnefo uses Google Ganeti backends for VM cluster management. In order Cyclades
to be able to handle thousand of user requests, Cyclades and Ganeti communicate
asynchronously. Briefly, requests are submitted to Ganeti, and asynchronous
notifications about the progress of jobs is received from the backends. The
architecture and communication with a Ganeti backend is shown in Figure?.
Cyclades API server is responsible for handling user requests. Read-only
requests are directly served by looking up the Cyclades DB. If the request
needs an action in the Ganeti backend, Cyclades submit jobs to the Ganeti
master using the Ganeti RAPI [1].
While Ganeti executes the job, snf-ganeti-eventd, snf-ganeti-hook and
snf-progress-monitor are monitoring the progress of the job and send
corresponding messages to the RabbitMQ servers. Specially,
* *snf-ganeti-eventd* sends messages about operations affecting the operating
state of instances and networks. Works by monitoring Ganeti job queue.
* *snf-ganeti_hook* sends messages about the NIC of instances. It includes a
number of Ganeti hooks for customisation of operations[2].
* *snf-progress_monitor* sends messages about the progress of building a new
instance and image deployment, triggered by snf-image.
Snf-dispatcher consumes messages from the RabbitMQ queues, process these
messages and properly updates the state of Cyclades DB. Subsequent requests in
Cyclades API, will retrieve the updated state from the DB.
[1]: http://docs.ganeti.org/ganeti/2.2/html/rapi.html
[2]: http://docs.ganeti.org/ganeti/2.2/html/hooks.html
Prereqs
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