Ansible
=======

Ansible is a extra-simple Python API for doing 'remote things' over SSH.  

While Func, which I co-wrote, aspired to avoid using SSH and have it's own daemon infrastructure, Ansible aspires to be quite different and more minimal, but still able to grow more modularly over time. 

Principles
==========

    * Dead simple setup
    * No server or client daemons, uses existing SSHd
    * Only SSH keys are allowed for authentication
    * usage of ssh-agent is more or less required
    * plugins can be written in ANY language
    * as with Func, API usage is an equal citizen to CLI usage
    * use Python's multiprocessing capabilities to emulate Func's forkbomb logic

Requirements
============

For the server the tool is running from, *only*:

    * python 2.6 -- or a backport of the multiprocessing module
    * paramiko

Inventory file
==============

The default inventory file (-H) is ~/.ansible_hosts and is a list
of all hostnames to target with ansible, one per line.  These
can be hostnames or IPs

This list is further filtered by the pattern wildcard (-P) to target
specific hosts.

Comamnd line usage example
==========================

Run a module by name with arguments

ssh-agent bash
ssh-add ~/.ssh/id_rsa.pub
ansible -p "*.example.com" -m modName -a "arg1 arg2"

API Example
===========

The API is simple and returns basic datastructures.

import ansible
runner = ansible.Runner(command='inventory', host_list=['xyz.example.com', '...'])
data = runner.run()

{
    'xyz.example.com' : [ 'any kind of datastructure is returnable' ],
    'foo.example.com' : None, # failed to connect,
    ...
}

Additional options to runner include the number of forks, hostname
exclusion pattern, library path, and so on.  Read the source, it's not
complicated.

Parallelism
===========

Specify the number of forks to use, to run things in greater parallelism.

ansible -f 10 "*.example.com" -m modName -a "arg1 arg2"

10 forks.  The default is 3.  5 is right out.

Bundled Modules
===============

See the example library for modules, they can be written in any language
and simply return JSON to stdout.  The path to your ansible library is
specified with the "-L" flag should you wish to use a different location
than "~/ansible".  There is potential for a sizeable community to build
up around the library scripts.

Features not supported from Func (yet?)
============================================

   * Delegation for treeish topologies
   * Asynchronous modes for polling long running operations

Future plans
============

   * Dead-simple declarative configuration management using
     a runbook style recipe file
   * facts engine, including exec'ing facter if present

Author
======

Michael DeHaan <michael.dehaan@gmail.com> 

http://michaeldehaan.net/