@ -25,25 +25,37 @@ Let's use ansible's command line tool to reboot all web servers in Atlanta, 10 a
The -f 10 specifies the usage of 10 simultaneous processes.
Note that other than the command module, ansible modules do not work like simple scripts. They make the remote system look like you state, and run the commands neccessary to get it there. This is commonly refered to
as 'idempotency'.
..note::
Note that other than the :ref:`command` module, ansible modules do
not work like simple scripts. They make the remote system look like
you state, and run the commands necessary to get it there. This
is commonly referred to as 'idempotent'.
File Transfer & Templating
``````````````````````````
Ansible can SCP lots of files to multiple machines in parallel, and optionally use them as template sources.
Ansible can SCP lots of files to multiple machines in parallel, and
optionally use them as template sources.
To just transfer a file directly to many different servers::
ansible atlanta copy -a "/etc/hosts /tmp/hosts"
To use templating, first run the setup module to put the template variables you would like to use on the remote host. Then use the template module to write the files using the templates. Templates are written in Jinja2 format. Playbooks (covered elsewhere in the documentation) will run the setup module for you, making this even simpler.::
To use templating, first run the setup module to put the template
variables you would like to use on the remote host. Then use the
template module to write the files using the templates. Templates are
written in Jinja2 format. Playbooks (covered elsewhere in the
documentation) will run the setup module for you, making this even
simpler.::
ansible webservers -m setup -a "favcolor=red ntp_server=192.168.1.1"
ansible webservers -m template -a "src=/srv/motd.j2 dest=/etc/motd"
ansible webservers -m template -a "src=/srv/ntp.j2 dest=/etc/ntp.conf"
Need something like the fqdn in a template? If facter or ohai are installed, data from these projects will also be made available to the template engine, using 'facter' and 'ohai' prefixes for each.
Need something like the fqdn in a template? If facter or ohai are
installed, data from these projects will also be made available to the
template engine, using 'facter' and 'ohai' prefixes for each.
Deploying From Source Control
`````````````````````````````
@ -52,7 +64,10 @@ Deploy your webapp straight from git::
ansible webservers -m git -a "repo=git://foo dest=/srv/myapp version=HEAD"
Since ansible modules can notify change handlers (see 'Playbooks') it is possible to tell ansible to run specific tasks when the code is updated, such as deploying Perl/Python/PHP/Ruby directly from git and then restarting apache.
Since ansible modules can notify change handlers (see
:doc:`playbooks`) it is possible to tell ansible to run specific tasks
when the code is updated, such as deploying Perl/Python/PHP/Ruby
directly from git and then restarting apache.
Managing Services
`````````````````
@ -68,14 +83,19 @@ Alternatively, restart a service on all webservers::
Time Limited Background Operations
``````````````````````````````````
Long running operations can be backgrounded, and their status can be checked on later. The same job ID is given to the same task on all hosts, so you won't lose track. Polling support is pending in the command line.::
Long running operations can be backgrounded, and their status can be
checked on later. The same job ID is given to the same task on all
hosts, so you won't lose track. Polling support is pending in the
command line.::
ansible all -B 3600 -a "/usr/bin/long_running_operation --do-stuff"
ansible all -n job_status -a jid=123456789
Any module other than 'copy' or 'template' can be backgrounded. Typically you'll be backgrounding shell
commands or software upgrades only.
Any module other than :ref:`copy` or :ref:`template` can be
backgrounded. Typically you'll be backgrounding shell commands or
software upgrades only.
After the time limit (in seconds) runs out (-B), the process on the remote nodes will be killed.
After the time limit (in seconds) runs out (``-B``), the process on
Ansible is a radically simple deployment, configuration, and command execution framework.
Other tools in this space have been too complicated for too long, require too much bootstrapping,
and have too much learning curve. Ansible is dead simple and painless to extend. For comparison, Puppet and Chef have about 60k lines of code. Ansible's core is a little over 1000 lines.
Ansible isn't just for configuration -- it's also great for Ad-Hoc tasks,
quickly firing off commands against nodes. Where Ansible excels though, is expressing complex multi-node deployment processes, executing complex sequences of commands on different hosts through "playbooks".
Extending ansible does not require programming in any particular language -- you can write modules
as scripts or programs that return simple JSON. It's also trivially easy to just execute
useful shell commands.
Why use Ansible versus something else? (Puppet, Chef, Fabric, Capistrano,
mCollective, Func, SaltStack, etc?) Ansible will have far less code, it
will be (by extension) 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.
Systems management doesn't have to be complicated. Ansible's docs will remain
short & simple, and the source will be blindingly obvious.
Ansible is a radically simple deployment, configuration, and command
execution framework. Other tools in this space have been too
complicated for too long, require too much bootstrapping, and have too
much learning curve. Ansible is dead simple and painless to extend.
For comparison, Puppet and Chef have about 60k lines of code.
Ansible's core is a little over 1000 lines.
Ansible isn't just for configuration -- it's also great for Ad-Hoc
tasks, quickly firing off commands against nodes. Where Ansible
excels though, is expressing complex multi-node deployment processes,
executing complex sequences of commands on different hosts through
:doc:`playbooks`.
Extending ansible does not require programming in any particular
language -- you can write modules as scripts or programs that return
simple JSON. It's also trivially easy to just execute useful shell
commands.
Why use Ansible versus something else? (Puppet, Chef, Fabric,
Capistrano, mCollective, Func, SaltStack, etc?) Ansible will have far
less code, it will be (by extension) 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.
Systems management doesn't have to be complicated. Ansible's docs
will remain short & simple, and the source will be blindingly obvious.
Design Goals
@ -40,7 +48,8 @@ Design Goals
Communicate and Get Involved
````````````````````````````
Your ideas and contributions are welcome. We're also happy to help you with questions about Ansible.
Your ideas and contributions are welcome. We're also happy to help
you with questions about Ansible.
* Join the `ansible-project mailing list <http://groups.google.com/group/ansible-project>`_ on Google Groups
* Join `#ansible <irc://irc.freenode.net/#ansible>`_ on the `freenode IRC network <http://freenode.net/>`_
@ -67,11 +76,13 @@ Contents
About the Author
````````````````
Ansible was originally developed by Michael DeHaan, a Raleigh, NC based software developer and architect.
He created other popular DevOps programs such as Cobbler, the popular Linux install server.
Cobbler is used to deploy mission critical systems all over the planet, in industries
ranging from massively multiplayer gaming, core internet infrastructure, finance,
chip design, and more. Michael also helped co-author of Func, a precursor to Ansible, which is used
to orchestrate systems in lots of diverse places. He's worked on systems software for
IBM, Motorola, Red Hat's Emerging Technologies Group, Puppet Labs, and rPath.
Ansible was originally developed by Michael DeHaan, a Raleigh, NC
based software developer and architect. He created other popular
DevOps programs such as Cobbler, the popular Linux install server.
Cobbler is used to deploy mission critical systems all over the
planet, in industries ranging from massively multiplayer gaming, core
internet infrastructure, finance, chip design, and more. Michael also
helped co-author of Func, a precursor to Ansible, which is used to
orchestrate systems in lots of diverse places. He's worked on systems
software for IBM, Motorola, Red Hat's Emerging Technologies Group,
Ansible ships with a number of modules that can be executed directly on remote hosts or through
ansible playbooks.
Ansible ships with a number of modules that can be executed directly
on remote hosts or through ansible playbooks.
..seealso::
@ -13,23 +13,29 @@ ansible playbooks.
:doc:`api`
Examples of using modules with the Python API
Nearly all modules take key=value parameters. Some modules take no parameters, and the command
module just takes arguments for the command you want to run.
Nearly all modules take ``key=value`` parameters. Some modules take
no parameters, and the command module just takes arguments for the
command you want to run.
All modules return JSON format data, thoug if you are using the command line or playbooks, you
don't really need to know much about that.
All modules return JSON format data, though if you are using the
command line or playbooks, you don't really need to know much about
that.
Most modules other than command are idempotent, meaning they will seek to avoid changes
unless a change needs to be made. When using ansible playbooks, these modules can
trigger change events. Unless otherwise noted, all modules support change hooks.
Most modules other than command are idempotent, meaning they will seek
to avoid changes unless a change needs to be made. When using ansible
playbooks, these modules can trigger change events. Unless otherwise
noted, all modules support change hooks.
Stock modules:
.._command:
command
```````
The command module takes the command name followed by a list of arguments, space delimited.
This is the only module that does not use key=value style parameters.
The command module takes the command name followed by a list of
arguments, space delimited. This is the only module that does not use
``key=value`` style parameters.
Example usage::
@ -37,27 +43,33 @@ Example usage::
The given shell command will be executed on all selected nodes.
This module does not support change hooks and returns the return code from the program as well as timing information about how long the command was running for.
This module does not support change hooks and returns the return code
from the program as well as timing information about how long the
command was running for.
.._copy:
copy
````
The copy module moves a file on the local box to remote locations.
*src*::
*src*:
Local path to a file to copy to the remote server. This can be an absolute or relative path.
* Local path to a file to copy to the remote server. This can be an
absolute or relative path.
*dest*::
*dest*:
Remote absolute path where the file should end up.
* Remote absolute path where the file should end up.
This module also returns md5sum information about the resultant file.
.._facter:
facter
``````
@ -66,9 +78,10 @@ JSON data that can be useful for inventory purposes.
Requires that 'facter' and 'ruby-json' be installed on the remote end.
This module is informative only - it takes no parameters & does not support change hooks,
nor does it make any changes on the system. Playbooks do not actually use
this module, they use the 'setup' module behind the scenes.
This module is informative only - it takes no parameters & does not
support change hooks, nor does it make any changes on the system.
Playbooks do not actually use this module, they use the :ref:`setup`
module behind the scenes.
git
@ -76,41 +89,43 @@ git
Deploys software (or files) from git checkouts.
*repo*::
*repo*:
git or http protocol address of the repo to checkout
* git or http protocol address of the repo to checkout.
*dest*::
*dest*:
where to check it out, an absolute directory path
* Where to check it out, an absolute directory path.
*version*::
*version*:
what version to check out -- either the git SHA, the literal string 'HEAD', or a tag name
* What version to check out -- either the git SHA, the literal string
``HEAD``, or a tag name.
ohai
````
Similar to the facter module, this returns JSON inventory data. Ohai
data is a bit more verbose and nested than facter.
Similar to the :ref:`facter` module, this returns JSON inventory data.
Ohai data is a bit more verbose and nested than facter.
Requires that 'ohai' be installed on the remote end.
This module is information only - it takes no parameters & does not
support change hooks, nor does it make any changes on the system.
Playbooks should not call the ohai module, playbooks call the 'setup'
module behind the scenes instead.
Playbooks should not call the ohai module, playbooks call the
:ref:`setup`module behind the scenes instead.
ping
````
A trivial test module, this module always returns the integer '1' on
A trivial test module, this module always returns the integer ``1`` on
successful contact.
This module does not support change hooks and is informative only - it takes no parameters & does not
support change hooks, nor does it make any changes on the system.
This module does not support change hooks and is informative only - it
takes no parameters & does not support change hooks, nor does it make
any changes on the system.
service
@ -118,51 +133,56 @@ service
Controls services on remote machines.
*state*
*state*:
Values are 'started', 'stopped', or 'restarted'. Started/stopped
are idempotent actions that will not run commands unless neccessary.
'restarted' will always bounce the service
* Values are ``started``, ``stopped``, or ``restarted``.
Started/stopped are idempotent actions that will not run commands
unless necessary. ``restarted`` will always bounce the service.
*name*
*name*:
The name of the service
* The name of the service.
.._setup:
setup
`````
Writes a JSON file containing key/value data, for use in templating.
Call this once before using the template modules. Playbooks will
execute this module automatically as the first step in each play using
the variables section, so it is unneccessary to make explicit calls to
setup within a playbook.
Call this once before using the :ref:`template` module. Playbooks
will execute this module automatically as the first step in each play
using the variables section, so it is unnecessary to make explicit
calls to setup within a playbook.
If facter or ohai are installed, variables from these programs will
also be snapshotted into the JSON file for usage in templating. These
variables are prefixed with ``facter_`` and ``ohai_`` so it's easy to
tell their source. All variables are then bubbled up to the caller.
If facter or ohai are installed, variables from these programs will also
be snapshotted into the JSON file for usage in templating. These variables
are prefixed with 'facter_' and 'ohai_" so it's easy to tell their source.
All variables are then bubbled up to the caller.
*anything*:
*anything*
* Any other parameters can be named basically anything, and set a
``key=value`` pair in the JSON file for use in templating.
any other parameters can be named basically anything, and set a key=value
pair in the JSON file for use in templating.
.._template:
template
````````
Templates a file out to a remote server. Call the setup module prior to usage.
Templates a file out to a remote server. Call the :ref:`setup` module
prior to usage.
*src*
*src*:
path of a Jinja2 formatted template on the local server. This can be a relative
or absolute path.
* Path of a Jinja2 formatted template on the local server. This can
be a relative or absolute path.
*dest*
*dest*:
location to render the template on the remote server
* Location to render the template on the remote server.
This module also returns md5sum information about the resultant file.
@ -171,29 +191,30 @@ This module also returns md5sum information about the resultant file.
Writing your own modules
````````````````````````
To write your own modules, simply follow the convention of those already available in
/usr/share/ansible. Modules must return JSON but can be written in any language.
Modules should return hashes, but hashes can be nested.
To write your own modules, simply follow the convention of those
already available in /usr/share/ansible. Modules must return JSON but
can be written in any language. Modules should return hashes, but
hashes can be nested.
To support change hooks, modules should return hashes with a changed: True/False
element at the top level::
To support change hooks, modules should return hashes with a changed:
True/False element at the top level::
{
'changed' : True,
'something' : 42
}
Modules can also choose to indicate a failure scenario by returning a top level 'failure'
element with a True value, and a 'msg' element describing the nature of the failure.
Other return values are up to the module.
Modules can also choose to indicate a failure scenario by returning a
top level ``failure`` element with a True value, and a ``msg`` element
describing the nature of the failure. Other return values are up to
the module::
{
'failure' : True,
'msg' : "here is what happened..."
}
When shipping modules, drop them in /usr/share/ansible, or specify the module path to the
command line tool or API. It is easy to test modules by running them directly on
the command line, passing them arguments just like they would be passed with ansible.
When shipping modules, drop them in /usr/share/ansible, or specify the
module path to the command line tool or API. It is easy to test
modules by running them directly on the command line, passing them
arguments just like they would be passed with ansible.
Tim Bielawa
12 years ago