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Further README tweaks

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Michael DeHaan 2012-02-26 23:03:06 -05:00
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README.md
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@ -2,7 +2,7 @@ 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
executing commands, running "modules", or executing larger 'playbooks' that
can serve as a configuration management or deployment system.
While [Func](http://fedorahosted.org/func), which I co-wrote,
@ -11,7 +11,8 @@ 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.
code in Y. Further, playbooks take things a whole step further, building the config
and deployment system I always wanted to build.
Why use Ansible versus something else? (Fabric, Capistrano, mCollective,
Func, SaltStack, etc?) It will have far less code, it will be more correct,
@ -25,34 +26,31 @@ Design Principles
* Dead simple setup
* Super fast & parallel by default
* No server or client daemons, uses existing SSHd
* No server or client daemons; use existing SSHd
* No additional software required on client boxes
* Everything is self updating on the clients
* Plugins can be written in ANY language
* API usage is an equal citizen to CLI usage
* Can be controlled/installed/used as non-root
* Modules can be written in ANY language
* Awesome API for creating very powerful distributed scripts
* Be usable as non-root
* Create the easiest config management system to use, ever.
Requirements
============
For the server the tool is running from, *only*:
* python 2.6 -- or the 2.4/2.5 backport of the multiprocessing module
* PyYAML (install on 'overlord' if using playbooks)
* paramiko
* python 2.6 (or the 2.4/2.5 backport of the multiprocessing module)
* PyYAML (only if using playbooks)
Optional -- If you want to push templates, the nodes need:
Optional -- If you want to push templates, the nodes need a template library,
which for bonus points you can install with ansible! Easy enough.
* python-jinja2
Inventory file
==============
To use ansible you must have a list of hosts somewhere.
The default inventory file (-H) is /etc/ansible/hosts and is a list
of all hostnames to manage with ansible, one per line. These
can be hostnames or IPs
To use ansible you must have a list of hosts somewhere. The default inventory file (override with -H) is /etc/ansible/hosts and is a list of all hostnames to manage with ansible, one per line. These can be hostnames or IPs.
Example:
@ -61,11 +59,8 @@ Example:
192.168.10.50
192.168.10.51
This list is further filtered by the pattern wildcard (-P) to target
specific hosts. This is covered below.
You can organize groups of systems by having multiple inventory
files (i.e. keeping webservers different from dbservers, etc)
This list is further filtered by the pattern wildcard (-p) to target
specific hosts. This is covered below. You can also organize groups of systems by having multiple inventory files (i.e. keeping webservers different from dbservers, etc)
Massive Parallelism, Pattern Matching, and a Usage Example
==========================================================
@ -76,6 +71,10 @@ Reboot all web servers in Atlanta, 10 at a time:
* ssh-add ~/.ssh/id_rsa.pub
* ansible -p "atlanta-web*" -f 10 -n command -a "/sbin/reboot"
Other than the comamnd module, though, ansible modules are not scripts. They make
the remote system look like you state, and run the commands neccessary to get it
there.
File Transfer
=============
@ -93,6 +92,9 @@ placed by 'setup' can be reused between ansible runs.
* ansible -p "*" -n template /srv/motd.j2 /etc/motd
* ansible -p "*" -n template /srv/foo.j2 /etc/foo
Very soon, templates will be able to also include facter and ohai
variables.
Git Deployments
===============
@ -104,7 +106,7 @@ Take Inventory
==============
Run popular open-source data discovery tools across a wide number of hosts.
This is best used from API scripts.
This is best used from API scripts that want to learn about remote systems.
* ansible -p "dbserver*" -n facter
* ansible -p "dbserver"" -n ohai
@ -113,7 +115,8 @@ Other Modules
=============
See the library directory for lots of extras. There's also a manpage,
ansible-modules(5).
ansible-modules(5) that covers all the options they take. You can
read the asciidoc in github in the 'docs' directory.
Playbooks
=========