index.txt

###
xal
###

This document contains contents of xal poster session at `EuroPython 2013 in
Florence, Italy <https://ep2013.europython.eu/>`_.

* Poster as PDF:
  https://github.com/benoitbryon/xal/raw/master/docs/presentations/2013-europython/poster.pdf

* Sources:
  https://github.com/benoitbryon/xal/tree/master/docs/presentations/2013-europython


********
Abstract
********

XAL is a proof of concept designed to write high-level scripts you can reuse
within various tools such as Fabric, zc.buildout, Salt…

Python has strong features for sysadmin scripts: portability, a shell and great
libraries. But, currently, you develop using tool’s specific implementation. As
a consequence, users of each project develop different tools that do similar
things.

XAL proposes a new approach for system-related scripts: develop to a session.
Write scripts that get a session as argument. That session is an abstraction
layer for system resources such as files, users, packages… It is just like an
ORM abstracts the database implementation. This design makes it possible to
share sysadmin scripts that you can use within all those great Python tools
related to system and deployment. Reduced cost of change and improved
collaboration!

This poster will present the concepts of XAL. This project is a
proof-of-concept, so the author will be glad to get feedback, discuss the ideas
and, if you are interested in, sprint on it!


***
xal
***

xal
  execution abstraction layer
  for high-level system scripts


********************
Develop to a session
********************

.. code:: python

   def greetings(session):
       """Write 'Hello world!' in 'greetings.txt' file relative to user's home."""
       home = session.user.home
       file_path = session.file.join(home, u'greetings.txt')
       file_resource = session.file(file_path)
       with file_resource.open('w'):
           file_resource.write(u'Hello world!')


.. raw:: pdf

   PageBreak

***************
Run it anywhere
***************

Shell
=====

In an interactive shell:

.. code:: pycon

   >>> from europython import greetings
   >>> import xal
   >>> session = xal.LocalSession()
   >>> greetings(session)

Fabric
======

In a fabfile:

.. code:: python

   from europython import greetings
   import xal

   def hello_fabric():
       session = xal.FabricSession(sudoer=True)
       greetings(session)


zc.buildout
===========

In a buildout recipe:

.. code:: python

   from europython import greetings
   import xal

   class HelloBuildout(object):
       def __init__(self, buildout, name, options):
           self.session = xal.BuildoutSession(buildout, name, options)

       def install(self):
           greetings(self.session)

Salt
====

In a salt module:

.. code:: python

   from europython import greetings
   import xal

   def hello_salt():
       session = xal.SaltSession(__salt__)
       greetings(session)


***************
Share libraries
***************

xal enables wider cooperation in Python community


*********************
Improve your workflow
*********************

* Do not wait for full provisioning stack, enter your project ASAP
* First focus on what your script does
* Then configure execution environment
* Build the provisioning stack incrementally
* Change provisioner, keep deployment recipes

*****************************
Exit the subprocess labyrinth
*****************************

* subprocess
* async_subprocess
* chut
* clom
* Command
* commandwrapper
* cpopen
* desub
* EasyProcess
* envoy
* execute
* extcmd
* extproc
* gevent_subprocess
* iterpipes
* pbs
* pipeline
* pyutilib.subprocess
* sarge
* seminode.utils.command
* sh
* shellout
* spur
* subwrap
* ... and more...
* ... and maybe yours

Could xal help APIs converge?


**********
Challenges
**********

* xal needs strong APIs:

  * run commands (subprocess wrapper)
  * consistent set of resources (files, users...)

  => PEPs?

* Efficient and comprehensive session registry
* Preconfigured registries: fabric, salt, buildout, local session...
* Resolution of session's dependencies
* Smart handling of NotImplementedError
* Unit tests with mocks, integration tests


*************************
xal is a proof of concept
*************************

https://xal.readthedocs.org


****************
Credits, license
****************

xal is released under BSD license
|copy| 2012-2013, Benoît Bryon

.. |copy| unicode:: 0xA9 .. copyright sign