You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
ansible/README.md

179 lines
5.3 KiB
Markdown

13 years ago
Ansible
=======
Ansible is a extra-simple tool/API for doing 'parallel remote things' over SSH -- whether
executing commands, running declarative 'modules', or executing larger 'playbooks' that
can serve as a configuration management or deployment system.
13 years ago
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
=================
13 years ago
13 years ago
* Dead simple setup
* Super fast & parallel by default
13 years ago
* No server or client daemons, uses existing SSHd
* No additional software required on client boxes
* 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
13 years ago
Requirements
============
13 years ago
For the server the tool is running from, *only*:
* python 2.6 -- or the 2.4/2.5 backport of the multiprocessing module
* PyYAML (if using playbooks)
13 years ago
* paramiko
13 years ago
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 default inventory file (-H) is /etc/ansible/hosts and is a list
13 years ago
of all hostnames to target with ansible, one per line. These
can be hostnames or IPs
13 years ago
Example:
abc.example.com
def.example.com
192.168.10.50
192.168.10.51
13 years ago
This list is further filtered by the pattern wildcard (-P) to target
specific hosts. This is covered below.
13 years ago
13 years ago
You can organize groups of systems by having multiple inventory
files (i.e. keeping webservers different from dbservers, etc)
Command line usage example
13 years ago
==========================
Run a module by name with arguments
* ssh-agent bash
* ssh-add ~/.ssh/id_rsa.pub
* ansible -p "*.example.com" -n modName -a "arg1 arg2"
13 years ago
API Example
===========
The API is simple and returns basic datastructures. Ansible will keep
track of which hosts were successfully contacted seperately from hosts
that had communication problems. The format of the return, if successful,
is entirely up to the module.
13 years ago
import ansible
runner = ansible.runner.Runner(
13 years ago
pattern='*',
module_name='inventory',
module_args='...'
13 years ago
)
data = runner.run()
13 years ago
{
'contacted' : {
'xyz.example.com' : [ 'any kind of datastructure is returnable' ],
'foo.example.com' : [ '...' ]
},
'dark' : {
'bar.example.com' : [ 'failure message' ]
}
}
13 years ago
13 years ago
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.
13 years ago
Patterns
========
To target only hosts starting with "rtp", for example:
* ansible -p "rtp*" -n command -a "yum update apache"
13 years ago
Parallelism
===========
Specify the number of forks to use, to run things in greater parallelism.
* ansible -f 10 "*.example.com" -n command -a "yum update apache"
13 years ago
13 years ago
10 forks. The default is 3. 5 is right out.
File Transfer
=============
13 years ago
Ansible can SCP lots of files to lots of places in parallel.
* ansible -p "web-*.acme.net" -f 10 -n copy -a "/etc/hosts /tmp/hosts"
Ansible Library (Bundled Modules)
=================================
13 years ago
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 "/usr/share/ansible". This means anyone can use Ansible, even without
root permissions.
There is potential for a sizeable community to build
13 years ago
up around the library scripts.
13 years ago
Modules include:
13 years ago
* command -- runs commands, giving output, return codes, and run time info
* ping - just returns if the system is up or not
* facter - retrieves facts about the host OS
* ohai - similar to facter, but returns structured data
* copy - add files to remote systems
13 years ago
Playbooks
=========
Playbooks are loosely equivalent to recipes or manifests in most configuration
management or deployment tools and describe a set of operations to run on
a set of hosts. Some tasks can choose to only fire when certain
conditions are true, and if a task in a chain fails the dependent tasks
will not proceed. Playbooks are described in (YAML)[http://yaml.org] format.
13 years ago
Future plans
============
* see TODO.md
13 years ago
License
=======
* MIT
13 years ago
Author
======
Michael DeHaan -- michael.dehaan@gmail.com
13 years ago
[http://michaeldehaan.net](http://michaeldehaan.net/)
13 years ago