Ansible is a extra-simple Python API for doing 'remote things' over SSH.
While [Func](http://fedorahosted.org/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. This is based on talking to a lot of users of various tools and wishing to eliminate problems with connectivity and long running daemons, or not picking tool X because they preferred to code in Y.
Why use Ansible versus something else? (Fabric, Capistrano, mCollective, Func, SaltStack, etc?) It will have far less code, it will be more correct, and it will be the easiest thing to hack on and use you'll ever see -- regardless of your favorite language of choice. Want to only code plugins in bash or clojure? Ansible doesn't care. The docs will fit on one page and the source will be blindingly obvious.
Principles
==========
While [Func](http://fedorahosted.org/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. This is based on talking to a lot of
users of various tools and wishing to eliminate problems with connectivity
and long running daemons, or not picking tool X because they preferred to
code in Y.
Why use Ansible versus something else? (Fabric, Capistrano, mCollective,
Func, SaltStack, etc?) It will have far less code, it will be more correct,
and it will be the easiest thing to hack on and use you'll ever see --
regardless of your favorite language of choice. Want to only code plugins
in bash or clojure? Ansible doesn't care. The docs will fit on one page
and the source will be blindingly obvious.
Design Principles
=================
* Dead simple setup
* Super fast & parallel by default
* No server or client daemons, uses existing SSHd
* No additional software required on client boxes
* Everything is self updating on the clients. "Modules" are remotely transferred to target boxes and exec'd, and do not stay active or consume resources.
* Only SSH keys are allowed for authentication
* usage of ssh-agent is more or less required (no passwords)
* 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
* all file paths can be specified as command line options easily allowing non-root usage
* Everything is self updating on the clients
* Encourages use of ssh-agent
* Plugins can be written in ANY language
* API usage is an equal citizen to CLI usage
* Can be controlled/installed/used as non-root
Requirements
============
@ -33,11 +42,11 @@ For the server the tool is running from, *only*:
Inventory file
==============
The inventory file is a required list of hostnames that can be potentially managed by
ansible. Eventually this file may be editable via the CLI, but for now, is
edited with your favorite text editor.
The inventory file is a required list of hostnames that can be
potentially managed by ansible. Eventually this file may be editable
via the CLI, but for now, is edited with your favorite text editor.
The default inventory file (-H) is ~/.ansible_hosts and is a list
The default inventory file (-H) is /etc/ansible/hosts and is a list
of all hostnames to target with ansible, one per line. These
can be hostnames or IPs
@ -71,8 +80,8 @@ The API is simple and returns basic datastructures.
import ansible
runner = ansible.Runner(
pattern='*',
module_name='inventory',
host_list=['xyz.example.com', '...']
module_name='inventory',
module_args='...'
)
data = runner.run()
@ -83,15 +92,15 @@ The API is simple and returns basic datastructures.
}
Additional options to Runner include the number of forks, hostname
exclusion pattern, library path, arguments, and so on. Read the source, it's not
complicated.
exclusion pattern, library path, arguments, and so on.
Read the source, it's not complicated.
Patterns
========
To target only hosts starting with "rtp", for example:
* ansible "rtp*" -n command -a "yum update apache"
* ansible -p "rtp*" -n command -a "yum update apache"
Parallelism
===========
@ -107,19 +116,21 @@ File Transfer
Ansible can SCP lots of files to lots of places in parallel.
* ansible -f 10 -n copy -a "/etc/hosts /tmp/hosts"
Michael DeHaan
12 years ago