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/
