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Ansible Resources
=================
User contributed playbooks, modules, and articles. This is a small
curated list, but growing. Everyone is encouraged to add to this
document, just `edit it on Github <https://github.com/ansible/ansible/blob/devel/docsite/latest/rst/contrib.rst>`_
and send a pull request!
Ansible Modules
```````````````
Ansible modules are a way of adding new client-side logic to ansible.
They can be written in any language. Generally our goal is to include most modules in core ("batteries included!"),
though a few may remain outside of core depending on use cases and implementations.
- `Official "core" ansible modules <http://www.ansibleworks.com/docs/modules.html>`_ - various
- `Linode <https://github.com/lextoumbourou/ansible-linode>`_ - Lex Toumbourou
- `zypper (bash module example) <https://github.com/jpmens/ansible-zypp>`_ - jp\_mens
- `additional provisioning-related modules <https://github.com/ansible-provisioning>`_ - jhoekx and dagwieers
- `dynamic dns updates <https://github.com/jpmens/ansible-m-dnsupdate>`_ - jp\_mens
- `apk-tools <http://git.alpinelinux.org/cgit/bpiotrowski/ansible-apk>`_ - Bartłomiej Piotrowski
All python modules (especially all submitted to core) should use the common "AnsibleModule" class to dramatically reduce the amount of boilerplate code required.
Not all modules above may take advantage of this feature. See the official documentation for more details.
Selected Playbooks
``````````````````
`Playbooks <http://www.ansibleworks.com/docs/playbooks.html>`_ are Ansible's
configuration management language. It should be easy to write your own
from scratch for most applications (we keep the language simple for EXACTLY that reason), but it can
be helpful to look at what others have done for reference and see what is possible.
The ansible-examples repo on github contains some examples of best-practices Ansible content deploying some
full stack workloads:
- `Ansible-Examples <http://github.com/ansible/ansible-examples>`_
And here are some other community-developed playbooks. Feel free to submit a pull request to the docs
to add your own.
- `edX Online <https://github.com/edx/configuration>`_ - `edX Online <http://edx.org>`_
- `Fedora Infrastructure <http://infrastructure.fedoraproject.org/cgit/ansible.git/tree/>`_ - `Fedora <http://fedoraproject.org>`_
- `Hadoop <https://github.com/jkleint/ansible-hadoop>`_ - jkleint
- `LAMP <https://github.com/fourkitchens/server-playbooks>`_ - `Four Kitchens <http://fourkitchens.com>`_
- `LEMP <https://github.com/francisbesset/ansible-playbooks>`_ - francisbesset
- `Ganglia (demo) <https://github.com/mpdehaan/ansible-examples>`_ - mpdehaan
- `Nginx <http://www.capsunlock.net/2012/04/ansible-nginx-playbook.html>`_ - cocoy
- `OpenStack <http://github.com/lorin/openstack-ansible>`_ - lorin
- `Systems Configuration <https://github.com/cegeddin/ansible-contrib>`_ - cegeddin
Callbacks and Plugins
`````````````````````
The Ansible project has a whole repo devoted to extending ansible with
new connection types, logging/event callbacks, and inventory data
storage. Talk to Cobbler and EC2, tweak the way things are logged, or
even add sound effects.
- `Ansible-Plugins <https://github.com/ansible/ansible/tree/devel/plugins>`_
- `Various modules, plugins, and scripts <https://github.com/ginsys/ansible-plugins>`_ sergevanginderachter
Scripts And Misc
````````````````
Ansible isn't just a program, it's also an API. Here's some examples of
some clever integrations with the "Runner" and also Playbook APIs, and
integrations with other interesting pieces of software.
- `Ansible Vagrant plugin <https://github.com/dsander/vagrant-ansible>`_ - dsander
- `Ansible+Vagrant Tutorial <https://github.com/mattupstate/vagrant-ansible-tutorial>`_ - mattupstate -
- `virt-install <http://fedorapeople.org/cgit/skvidal/public_git/scripts.git/tree/ansible/start-prov-boot.py>`_ - skvidal
- `rebooting hosts <http://fedorapeople.org/cgit/skvidal/public_git/scripts.git/tree/ansible/host-reboot>`_ - skvidal
- `uptime (API demo) <https://github.com/ansible/ansible/blob/devel/examples/scripts/uptime.py>`_ - mpdehaan
- `vim snippet generator <https://github.com/bleader/ansible_snippet_generator>`_ - bleader
Blogs, Videos & Articles
````````````````````````
- `HighScalability.com <http://highscalability.com/blog/2012/4/18/ansible-a-simple-model-driven-configuration-management-and-c.html>`_ - mpdehaan
- `ColoAndCloud.com interview <http://www.coloandcloud.com/editorial/an-interview-with-ansible-author-michael-dehaan/>`_ - mpdehaan
- `dzone <http://server.dzone.com/articles/ansible-cm-deployment-and-ad>`_ - Mitch Pronschinske
- `Configuration Management With Ansible <http://jpmens.net/2012/06/06/configuration-management-with-ansible/>`_ - jp\_mens
- `Shell Scripts As Ansible Modules <http://jpmens.net/2012/07/05/shell-scripts-as-ansible-modules/>`_ - jp\_mens
- `Ansible Facts <http://jpmens.net/2012/07/15/ansible-it-s-a-fact/>`_ - jp\_mens
- `Infrastructure as Data <http://www.capsunlock.net/2012/04/ansible-infrastructure-as-data-not-infrastructure-as-code.html>`_ - cocoy
- `Ansible Pull Mode <http://www.capsunlock.net/2012/05/using-ansible-pull-and-user-data-to-setup-ec2-or-openstack-servers.html>`_ - cocoy
- `Exploring Configuration Management With Ansible <http://palominodb.com/blog/2012/08/01/exploring-configuration-management-ansible>`_ - Palamino DB
- `You Should Consider Using SSH Based Configuration Management <http://www.lshift.net/blog/2012/07/30/you-should-consider-using-ssh-based-configuration-management>`_ - LShift Ltd
- `Deploying Flask/uWSGI, Nginx, and Supervisorctl <http://mattupstate.github.com/python/devops/2012/08/07/flask-wsgi-application-deployment-with-ubuntu-ansible-nginx-supervisor-and-uwsgi.html>`_ - mattupstate
- `Infracoders Presentation <http://www.danielhall.me/2012/10/ansible-talk-infra-coders/>`_ - Daniel Hall
- `Ansible - an introduction <https://speakerdeck.com/jpmens/ansible-an-introduction>`_ - jp\_mens
- `Using Ansible to setup complex networking - <http://exarv.nl/2013/02/using-ansible-to-setup-complex-networking/>`_ - Robert Verspuy
- `Video presentation to Montreal Linux <http://www.youtube.com/embed/up3ofvQNm8c>`_ - Alexandre Bourget
- `Provisioning CentOS EC2 Instances with Ansible <http://jpmens.net/2012/11/21/provisioning-centos-ec2-instances-with-ansible/>`_ - jp\_mens
Disclaimer
``````````
Modules and playbooks here may not be using the latest in Ansible
features. When in doubt to the features of a particular version of
Ansible, always consult `ansibleworks.com <http://www.ansibleworks.com/>`_ and in
particular see `Best Practices <http://www.ansibleworks.com/docs/bestpractices.html>`_
for some tips and tricks that may be useful.
Ansible is (C) 2012, `Michael DeHaan <http://twitter.com/laserllama>`_
and others and is available under the GPLv3 license. Content here is as
specified by individual contributors.

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API & Integrations
==================
There are several interesting ways to use Ansible from an API perspective. You can use
the Ansible python API to control nodes, you can extend Ansible to respond to various python events,
and you can plug in inventory data from external data sources. Ansible is written in its own
API so you have a considerable amount of power across the board.
.. contents:: `Table of contents`
:depth: 2
Python API
----------
The Python API is very powerful, and is how the ansible CLI and ansible-playbook
are implemented.
It's pretty simple::
import ansible.runner
runner = ansible.runner.Runner(
module_name='ping',
module_args='',
pattern='web*',
forks=10
)
datastructure = runner.run()
The run method returns results per host, grouped by whether they
could be contacted or not. Return types are module specific, as
expressed in the 'ansible-modules' documentation.::
{
"dark" : {
"web1.example.com" : "failure message"
},
"contacted" : {
"web2.example.com" : 1
}
}
A module can return any type of JSON data it wants, so Ansible can
be used as a framework to rapidly build powerful applications and scripts.
Detailed API Example
````````````````````
The following script prints out the uptime information for all hosts::
#!/usr/bin/python
import ansible.runner
import sys
# construct the ansible runner and execute on all hosts
results = ansible.runner.Runner(
pattern='*', forks=10,
module_name='command', module_args='/usr/bin/uptime',
).run()
if results is None:
print "No hosts found"
sys.exit(1)
print "UP ***********"
for (hostname, result) in results['contacted'].items():
if not 'failed' in result:
print "%s >>> %s" % (hostname, result['stdout'])
print "FAILED *******"
for (hostname, result) in results['contacted'].items():
if 'failed' in result:
print "%s >>> %s" % (hostname, result['msg'])
print "DOWN *********"
for (hostname, result) in results['dark'].items():
print "%s >>> %s" % (hostname, result)
Advanced programmers may also wish to read the source to ansible itself, for
it uses the Runner() API (with all available options) to implement the
command line tools ``ansible`` and ``ansible-playbook``.
Plugins Available Online
------------------------
The remainder of features in the API docs have components available in `ansible-plugins <https://github.com/ansible/ansible/blob/devel/plugins>`_. Send us a github pull request if you develop any interesting features.
External Inventory Scripts
--------------------------
Often a user of a configuration management system will want to keep inventory
in a different system. Frequent examples include LDAP, `Cobbler <http://cobbler.github.com>`_,
or a piece of expensive enterprisey CMDB software. Ansible easily supports all
of these options via an external inventory system. The plugins directory contains some of these already -- including options for EC2/Eucalyptus and OpenStack, which will be detailed below.
It's possible to write an external inventory script in any language. If you are familiar with Puppet terminology, this concept is basically the same as 'external nodes', with the slight difference that it also defines which hosts are managed.
Script Conventions
``````````````````
When the external node script is called with the single argument '--list', the script must return a JSON hash/dictionary of all the groups to be managed.
Each group's value should be either a hash/dictionary containing a list of each host/IP, potential child groups, and potential group variables, or
simply a list of host/IP addresses, like so::
{
"databases" : {
"hosts" : [ "host1.example.com", "host2.example.com" ],
"vars" : {
"a" : true
}
},
"webservers" : [ "host2.example.com", "host3.example.com" ],
"atlanta" : {
"hosts" : [ "host1.example.com", "host4.example.com", "host5.example.com" ],
"vars" : {
"b" : false
},
"children": [ "marietta", "5points" ],
},
"marietta" : [ "host6.example.com" ],
"5points" : [ "host7.example.com" ]
}
.. versionadded:: 1.0
Before version 1.0, each group could only have a list of hostnames/IP addresses, like the webservers, marietta, and 5points groups above.
When called with the arguments '--host <hostname>' (where <hostname> is a host from above), the script must return either an empty JSON
hash/dictionary, or a hash/dictionary of variables to make available to templates and playbooks. Returning variables is optional,
if the script does not wish to do this, returning an empty hash/dictionary is the way to go::
{
"favcolor" : "red",
"ntpserver" : "wolf.example.com",
"monitoring" : "pack.example.com"
}
Tuning the External Inventory Script
````````````````````````````````````
.. versionadded:: 1.3
The stock inventory script system detailed above works for all versions of Ansible, but calling
'--host' for every host can be rather expensive, especially if it involves expensive API calls to
a remote subsystemm. In Ansible
1.3 or later, if the inventory script returns a top level element called "_meta", it is possible
to return all of the host variables in one inventory script call. When this meta element contains
a value for "hostvars", the inventory script will not be invoked with "--host" for each host. This
results in a significant performance increase for large numbers of hosts, and also makes client
side caching easier to implement for the inventory script.
The data to be added to the top level JSON dictionary looks like this::
{
# results of inventory script as above go here
# ...
"_meta" : {
"hostvars" : {
"moocow.example.com" : { "asdf" : 1234 },
"llama.example.com" : { "asdf" : 5678 },
}
}
}
Example: The Cobbler External Inventory Script
``````````````````````````````````````````````
It is expected that many Ansible users will also be `Cobbler <http://cobbler.github.com>`_ users. Cobbler has a generic
layer that allows it to represent data for multiple configuration management systems (even at the same time), and has
been referred to as a 'lightweight CMDB' by some admins. This particular script will communicate with Cobbler
using Cobbler's XMLRPC API.
To tie Ansible's inventory to Cobbler (optional), copy `this script <https://raw.github.com/ansible/ansible/devel/plugins/inventory/cobbler.py>`_ to /etc/ansible/hosts and `chmod +x` the file. cobblerd will now need
to be running when you are using Ansible.
Test the file by running `./etc/ansible/hosts` directly. You should see some JSON data output, but it may not have
anything in it just yet.
Let's explore what this does. In cobbler, assume a scenario somewhat like the following::
cobbler profile add --name=webserver --distro=CentOS6-x86_64
cobbler profile edit --name=webserver --mgmt-classes="webserver" --ksmeta="a=2 b=3"
cobbler system edit --name=foo --dns-name="foo.example.com" --mgmt-classes="atlanta" --ksmeta="c=4"
cobbler system edit --name=bar --dns-name="bar.example.com" --mgmt-classes="atlanta" --ksmeta="c=5"
In the example above, the system 'foo.example.com' will be addressable by ansible directly, but will also be addressable when using the group names 'webserver' or 'atlanta'. Since Ansible uses SSH, we'll try to contract system foo over 'foo.example.com', only, never just 'foo'. Similarly, if you try "ansible foo" it wouldn't find the system... but "ansible 'foo*'" would, because the system DNS name starts with 'foo'.
The script doesn't just provide host and group info. In addition, as a bonus, when the 'setup' module is run (which happens automatically when using playbooks), the variables 'a', 'b', and 'c' will all be auto-populated in the templates::
# file: /srv/motd.j2
Welcome, I am templated with a value of a={{ a }}, b={{ b }}, and c={{ c }}
Which could be executed just like this::
ansible webserver -m setup
ansible webserver -m template -a "src=/tmp/motd.j2 dest=/etc/motd"
.. note::
The name 'webserver' came from cobbler, as did the variables for
the config file. You can still pass in your own variables like
normal in Ansible, but variables from the external inventory script
will override any that have the same name.
So, with the template above (motd.j2), this would result in the following data being written to /etc/motd for system 'foo'::
Welcome, I am templated with a value of a=2, b=3, and c=4
And on system 'bar' (bar.example.com)::
Welcome, I am templated with a value of a=2, b=3, and c=5
And technically, though there is no major good reason to do it, this also works too::
ansible webserver -m shell -a "echo {{ a }}"
So in other words, you can use those variables in arguments/actions as well. You might use this to name
a conf.d file appropriately or something similar. Who knows?
So that's the Cobbler integration support -- using the cobbler script as an example, it should be trivial to adapt Ansible to pull inventory, as well as variable information, from any data source. If you create anything interesting, please share with the mailing list, and we can keep it in the source code tree for others to use.
Example: AWS EC2 External Inventory Script
``````````````````````````````````````````
If you use Amazon Web Services EC2, maintaining an inventory file might not be the best approach. For this reason, you can use the `EC2 external inventory <https://raw.github.com/ansible/ansible/devel/plugins/inventory/ec2.py>`_ script.
You can use this script in one of two ways. The easiest is to use Ansible's ``-i`` command line option and specify the path to the script.
ansible -i ec2.py -u ubuntu us-east-1d -m ping
The second option is to copy the script to `/etc/ansible/hosts` and `chmod +x` it. You will also need to copy the `ec2.ini <https://raw.github.com/ansible/ansible/devel/plugins/inventory/ec2.ini>`_ file to `/etc/ansible/ec2.ini`. Then you can run ansible as you would normally.
To successfully make an API call to AWS, you will need to configure Boto (the Python interface to AWS). There are a `variety of methods <http://docs.pythonboto.org/en/latest/boto_config_tut.html>`_ available, but the simplest is just to export two environment variables:
export AWS_ACCESS_KEY_ID='AK123'
export AWS_SECRET_ACCESS_KEY='abc123'
You can test the script by itself to make sure your config is correct
cd plugins/inventory
./ec2.py --list
After a few moments, you should see your entire EC2 inventory across all regions in JSON.
Since each region requires its own API call, if you are only using a small set of regions, feel free to edit ``ec2.ini`` and list only the regions you are interested in. There are other config options in ``ec2.ini`` including cache control, and destination variables.
At their heart, inventory files are simply a mapping from some name to a destination address. The default ``ec2.ini`` settings are configured for running Ansible from outside EC2 (from your laptop for example). If you are running Ansible from within EC2, internal DNS names and IP addresses may make more sense than public DNS names. In this case, you can modify the ``destination_variable`` in ``ec2.ini`` to be the private DNS name of an instance. This is particularly important when running Ansible within a private subnet inside a VPC, where the only way to access an instance is via its private IP address. For VPC instances, `vpc_destination_variable` in ``ec2.ini`` provides a means of using which ever `boto.ec2.instance variable <http://docs.pythonboto.org/en/latest/ref/ec2.html#module-boto.ec2.instance>`_ makes the most sense for your use case.
The EC2 external inventory provides mappings to instances from several groups:
Instance ID
These are groups of one since instance IDs are unique.
e.g.
``i-00112233``
``i-a1b1c1d1``
Region
A group of all instances in an AWS region.
e.g.
``us-east-1``
``us-west-2``
Availability Zone
A group of all instances in an availability zone.
e.g.
``us-east-1a``
``us-east-1b``
Security Group
Instances belong to one or more security groups. A group is created for each security group, with all characters except alphanumerics, dashes (-) converted to underscores (_). Each group is prefixed by ``security_group_``
e.g.
``security_group_default``
``security_group_webservers``
``security_group_Pete_s_Fancy_Group``
Tags
Each instance can have a variety of key/value pairs associated with it called Tags. The most common tag key is 'Name', though anything is possible. Each key/value pair is its own group of instances, again with special characters converted to underscores, in the format ``tag_KEY_VALUE``
e.g.
``tag_Name_Web``
``tag_Name_redis-master-001``
``tag_aws_cloudformation_logical-id_WebServerGroup``
When the Ansible is interacting with a specific server, the EC2 inventory script is called again with the ``--host HOST`` option. This looks up the HOST in the index cache to get the instance ID, and then makes an API call to AWS to get information about that specific instance. It then makes information about that instance available as variables to your playbooks. Each variable is prefixed by ``ec2_``. Here are some of the variables available:
- ec2_architecture
- ec2_description
- ec2_dns_name
- ec2_id
- ec2_image_id
- ec2_instance_type
- ec2_ip_address
- ec2_kernel
- ec2_key_name
- ec2_launch_time
- ec2_monitored
- ec2_ownerId
- ec2_placement
- ec2_platform
- ec2_previous_state
- ec2_private_dns_name
- ec2_private_ip_address
- ec2_public_dns_name
- ec2_ramdisk
- ec2_region
- ec2_root_device_name
- ec2_root_device_type
- ec2_security_group_ids
- ec2_security_group_names
- ec2_spot_instance_request_id
- ec2_state
- ec2_state_code
- ec2_state_reason
- ec2_status
- ec2_subnet_id
- ec2_tag_Name
- ec2_tenancy
- ec2_virtualization_type
- ec2_vpc_id
Both ``ec2_security_group_ids`` and ``ec2_security_group_names`` are comma-separated lists of all security groups. Each EC2 tag is a variable in the format ``ec2_tag_KEY``.
To see the complete list of variables available for an instance, run the script by itself::
cd plugins/inventory
./ec2.py --host ec2-12-12-12-12.compute-1.amazonaws.com
Example: OpenStack Inventory Script
```````````````````````````````````
Though not detailed here in as much depth as the EC2 module, there's also a OpenStack Compute external inventory source in the plugins directory. It requires the Grizzly release of OpenStack or
later. See the inline comments in the module source for how to use it.
Callback Plugins
----------------
Ansible can be configured via code to respond to external events. This can include enhancing logging, signalling an external software
system, or even (yes, really) making sound effects. Some examples are contained in the plugins directory.
Connection Type Plugins
-----------------------
By default, ansible ships with a 'paramiko' SSH, native ssh (just called 'ssh'), and 'local' connection type, and an accelerated connection type named 'fireball'. All of these can be used
in playbooks and with /usr/bin/ansible to decide how you want to talk to remote machines. The basics of these connection types
are covered in the 'getting started' section. Should you want to extend Ansible to support other transports (SNMP? Message bus?
Carrier Pigeon?) it's as simple as copying the format of one of the existing modules and dropping it into the connection plugins
directory. The value of 'smart' for a connection allows selection of paramiko or openssh based on system capabilities, and chooses
'ssh' if OpenSSH supports ControlPersist, in Ansible 1.2.1 an later. Previous versions did not support 'smart'.
Lookup Plugins
--------------
Language constructs like "with_fileglob" and "with_items" are implemented via lookup plugins. Just like other plugin types, you can write your own.
Vars Plugins
------------
Playbook constructs like 'host_vars' and 'group_vars' work via 'vars' plugins. They inject additional variable
data into ansible runs that did not come from an inventory, playbook, or command line. Note that variables
can also be returned from inventory, so in most cases, you won't need to write or understand vars_plugins.
Filter Plugins
--------------
If you want more Jinja2 filters available in a Jinja2 template (filters like to_yaml and to_json are provided by default), they can be extended by writing a filter plugin.
Distributing Plugins
--------------------
.. versionadded:: 0.8
Plugins are loaded from both Python's site_packages (those that ship with ansible) and a configured plugins directory, which defaults
to /usr/share/ansible/plugins, in a subfolder for each plugin type::
* action_plugins
* lookup_plugins
* callback_plugins
* connection_plugins
* filter_plugins
* vars_plugins
To change this path, edit the ansible configuration file.
In addition, plugins can be shipped in a subdirectory relative to a top-level playbook, in folders named the same as indicated above.
.. seealso::
:doc:`modules`
List of built-in modules
`Mailing List <http://groups.google.com/group/ansible-project>`_
Questions? Help? Ideas? Stop by the list on Google Groups
`irc.freenode.net <http://irc.freenode.net>`_
#ansible IRC chat channel

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API & Integrations
==================
There are several interesting ways to use Ansible from an API perspective. You can use
the Ansible python API to control nodes, you can extend Ansible to respond to various python events,
and you can plug in inventory data from external data sources. Ansible is written in its own
API so you have a considerable amount of power across the board.
.. contents:: `Table of contents`
:depth: 2
Python API
----------
The Python API is very powerful, and is how the ansible CLI and ansible-playbook
are implemented.
It's pretty simple::
import ansible.runner
runner = ansible.runner.Runner(
module_name='ping',
module_args='',
pattern='web*',
forks=10
)
datastructure = runner.run()
The run method returns results per host, grouped by whether they
could be contacted or not. Return types are module specific, as
expressed in the 'ansible-modules' documentation.::
{
"dark" : {
"web1.example.com" : "failure message"
},
"contacted" : {
"web2.example.com" : 1
}
}
A module can return any type of JSON data it wants, so Ansible can
be used as a framework to rapidly build powerful applications and scripts.
Detailed API Example
````````````````````
The following script prints out the uptime information for all hosts::
#!/usr/bin/python
import ansible.runner
import sys
# construct the ansible runner and execute on all hosts
results = ansible.runner.Runner(
pattern='*', forks=10,
module_name='command', module_args='/usr/bin/uptime',
).run()
if results is None:
print "No hosts found"
sys.exit(1)
print "UP ***********"
for (hostname, result) in results['contacted'].items():
if not 'failed' in result:
print "%s >>> %s" % (hostname, result['stdout'])
print "FAILED *******"
for (hostname, result) in results['contacted'].items():
if 'failed' in result:
print "%s >>> %s" % (hostname, result['msg'])
print "DOWN *********"
for (hostname, result) in results['dark'].items():
print "%s >>> %s" % (hostname, result)
Advanced programmers may also wish to read the source to ansible itself, for
it uses the Runner() API (with all available options) to implement the
command line tools ``ansible`` and ``ansible-playbook``.
Plugins Available Online
------------------------
The remainder of features in the API docs have components available in `ansible-plugins <https://github.com/ansible/ansible/blob/devel/plugins>`_. Send us a github pull request if you develop any interesting features.
External Inventory Scripts
--------------------------
Often a user of a configuration management system will want to keep inventory
in a different system. Frequent examples include LDAP, `Cobbler <http://cobbler.github.com>`_,
or a piece of expensive enterprisey CMDB software. Ansible easily supports all
of these options via an external inventory system. The plugins directory contains some of these already -- including options for EC2/Eucalyptus and OpenStack, which will be detailed below.
It's possible to write an external inventory script in any language. If you are familiar with Puppet terminology, this concept is basically the same as 'external nodes', with the slight difference that it also defines which hosts are managed.
Script Conventions
``````````````````
When the external node script is called with the single argument '--list', the script must return a JSON hash/dictionary of all the groups to be managed.
Each group's value should be either a hash/dictionary containing a list of each host/IP, potential child groups, and potential group variables, or
simply a list of host/IP addresses, like so::
{
"databases" : {
"hosts" : [ "host1.example.com", "host2.example.com" ],
"vars" : {
"a" : true
}
},
"webservers" : [ "host2.example.com", "host3.example.com" ],
"atlanta" : {
"hosts" : [ "host1.example.com", "host4.example.com", "host5.example.com" ],
"vars" : {
"b" : false
},
"children": [ "marietta", "5points" ],
},
"marietta" : [ "host6.example.com" ],
"5points" : [ "host7.example.com" ]
}
.. versionadded:: 1.0
Before version 1.0, each group could only have a list of hostnames/IP addresses, like the webservers, marietta, and 5points groups above.
When called with the arguments '--host <hostname>' (where <hostname> is a host from above), the script must return either an empty JSON
hash/dictionary, or a hash/dictionary of variables to make available to templates and playbooks. Returning variables is optional,
if the script does not wish to do this, returning an empty hash/dictionary is the way to go::
{
"favcolor" : "red",
"ntpserver" : "wolf.example.com",
"monitoring" : "pack.example.com"
}
Tuning the External Inventory Script
````````````````````````````````````
.. versionadded:: 1.3
The stock inventory script system detailed above works for all versions of Ansible, but calling
'--host' for every host can be rather expensive, especially if it involves expensive API calls to
a remote subsystemm. In Ansible
1.3 or later, if the inventory script returns a top level element called "_meta", it is possible
to return all of the host variables in one inventory script call. When this meta element contains
a value for "hostvars", the inventory script will not be invoked with "--host" for each host. This
results in a significant performance increase for large numbers of hosts, and also makes client
side caching easier to implement for the inventory script.
The data to be added to the top level JSON dictionary looks like this::
{
# results of inventory script as above go here
# ...
"_meta" : {
"hostvars" : {
"moocow.example.com" : { "asdf" : 1234 },
"llama.example.com" : { "asdf" : 5678 },
}
}
}
Example: The Cobbler External Inventory Script
``````````````````````````````````````````````
It is expected that many Ansible users will also be `Cobbler <http://cobbler.github.com>`_ users. Cobbler has a generic
layer that allows it to represent data for multiple configuration management systems (even at the same time), and has
been referred to as a 'lightweight CMDB' by some admins. This particular script will communicate with Cobbler
using Cobbler's XMLRPC API.
To tie Ansible's inventory to Cobbler (optional), copy `this script <https://raw.github.com/ansible/ansible/devel/plugins/inventory/cobbler.py>`_ to /etc/ansible/hosts and `chmod +x` the file. cobblerd will now need
to be running when you are using Ansible.
Test the file by running `./etc/ansible/hosts` directly. You should see some JSON data output, but it may not have
anything in it just yet.
Let's explore what this does. In cobbler, assume a scenario somewhat like the following::
cobbler profile add --name=webserver --distro=CentOS6-x86_64
cobbler profile edit --name=webserver --mgmt-classes="webserver" --ksmeta="a=2 b=3"
cobbler system edit --name=foo --dns-name="foo.example.com" --mgmt-classes="atlanta" --ksmeta="c=4"
cobbler system edit --name=bar --dns-name="bar.example.com" --mgmt-classes="atlanta" --ksmeta="c=5"
In the example above, the system 'foo.example.com' will be addressable by ansible directly, but will also be addressable when using the group names 'webserver' or 'atlanta'. Since Ansible uses SSH, we'll try to contract system foo over 'foo.example.com', only, never just 'foo'. Similarly, if you try "ansible foo" it wouldn't find the system... but "ansible 'foo*'" would, because the system DNS name starts with 'foo'.
The script doesn't just provide host and group info. In addition, as a bonus, when the 'setup' module is run (which happens automatically when using playbooks), the variables 'a', 'b', and 'c' will all be auto-populated in the templates::
# file: /srv/motd.j2
Welcome, I am templated with a value of a={{ a }}, b={{ b }}, and c={{ c }}
Which could be executed just like this::
ansible webserver -m setup
ansible webserver -m template -a "src=/tmp/motd.j2 dest=/etc/motd"
.. note::
The name 'webserver' came from cobbler, as did the variables for
the config file. You can still pass in your own variables like
normal in Ansible, but variables from the external inventory script
will override any that have the same name.
So, with the template above (motd.j2), this would result in the following data being written to /etc/motd for system 'foo'::
Welcome, I am templated with a value of a=2, b=3, and c=4
And on system 'bar' (bar.example.com)::
Welcome, I am templated with a value of a=2, b=3, and c=5
And technically, though there is no major good reason to do it, this also works too::
ansible webserver -m shell -a "echo {{ a }}"
So in other words, you can use those variables in arguments/actions as well. You might use this to name
a conf.d file appropriately or something similar. Who knows?
So that's the Cobbler integration support -- using the cobbler script as an example, it should be trivial to adapt Ansible to pull inventory, as well as variable information, from any data source. If you create anything interesting, please share with the mailing list, and we can keep it in the source code tree for others to use.
Example: AWS EC2 External Inventory Script
``````````````````````````````````````````
If you use Amazon Web Services EC2, maintaining an inventory file might not be the best approach. For this reason, you can use the `EC2 external inventory <https://raw.github.com/ansible/ansible/devel/plugins/inventory/ec2.py>`_ script.
You can use this script in one of two ways. The easiest is to use Ansible's ``-i`` command line option and specify the path to the script.
ansible -i ec2.py -u ubuntu us-east-1d -m ping
The second option is to copy the script to `/etc/ansible/hosts` and `chmod +x` it. You will also need to copy the `ec2.ini <https://raw.github.com/ansible/ansible/devel/plugins/inventory/ec2.ini>`_ file to `/etc/ansible/ec2.ini`. Then you can run ansible as you would normally.
To successfully make an API call to AWS, you will need to configure Boto (the Python interface to AWS). There are a `variety of methods <http://docs.pythonboto.org/en/latest/boto_config_tut.html>`_ available, but the simplest is just to export two environment variables:
export AWS_ACCESS_KEY_ID='AK123'
export AWS_SECRET_ACCESS_KEY='abc123'
You can test the script by itself to make sure your config is correct
cd plugins/inventory
./ec2.py --list
After a few moments, you should see your entire EC2 inventory across all regions in JSON.
Since each region requires its own API call, if you are only using a small set of regions, feel free to edit ``ec2.ini`` and list only the regions you are interested in. There are other config options in ``ec2.ini`` including cache control, and destination variables.
At their heart, inventory files are simply a mapping from some name to a destination address. The default ``ec2.ini`` settings are configured for running Ansible from outside EC2 (from your laptop for example). If you are running Ansible from within EC2, internal DNS names and IP addresses may make more sense than public DNS names. In this case, you can modify the ``destination_variable`` in ``ec2.ini`` to be the private DNS name of an instance. This is particularly important when running Ansible within a private subnet inside a VPC, where the only way to access an instance is via its private IP address. For VPC instances, `vpc_destination_variable` in ``ec2.ini`` provides a means of using which ever `boto.ec2.instance variable <http://docs.pythonboto.org/en/latest/ref/ec2.html#module-boto.ec2.instance>`_ makes the most sense for your use case.
The EC2 external inventory provides mappings to instances from several groups:
Instance ID
These are groups of one since instance IDs are unique.
e.g.
``i-00112233``
``i-a1b1c1d1``
Region
A group of all instances in an AWS region.
e.g.
``us-east-1``
``us-west-2``
Availability Zone
A group of all instances in an availability zone.
e.g.
``us-east-1a``
``us-east-1b``
Security Group
Instances belong to one or more security groups. A group is created for each security group, with all characters except alphanumerics, dashes (-) converted to underscores (_). Each group is prefixed by ``security_group_``
e.g.
``security_group_default``
``security_group_webservers``
``security_group_Pete_s_Fancy_Group``
Tags
Each instance can have a variety of key/value pairs associated with it called Tags. The most common tag key is 'Name', though anything is possible. Each key/value pair is its own group of instances, again with special characters converted to underscores, in the format ``tag_KEY_VALUE``
e.g.
``tag_Name_Web``
``tag_Name_redis-master-001``
``tag_aws_cloudformation_logical-id_WebServerGroup``
When the Ansible is interacting with a specific server, the EC2 inventory script is called again with the ``--host HOST`` option. This looks up the HOST in the index cache to get the instance ID, and then makes an API call to AWS to get information about that specific instance. It then makes information about that instance available as variables to your playbooks. Each variable is prefixed by ``ec2_``. Here are some of the variables available:
- ec2_architecture
- ec2_description
- ec2_dns_name
- ec2_id
- ec2_image_id
- ec2_instance_type
- ec2_ip_address
- ec2_kernel
- ec2_key_name
- ec2_launch_time
- ec2_monitored
- ec2_ownerId
- ec2_placement
- ec2_platform
- ec2_previous_state
- ec2_private_dns_name
- ec2_private_ip_address
- ec2_public_dns_name
- ec2_ramdisk
- ec2_region
- ec2_root_device_name
- ec2_root_device_type
- ec2_security_group_ids
- ec2_security_group_names
- ec2_spot_instance_request_id
- ec2_state
- ec2_state_code
- ec2_state_reason
- ec2_status
- ec2_subnet_id
- ec2_tag_Name
- ec2_tenancy
- ec2_virtualization_type
- ec2_vpc_id
Both ``ec2_security_group_ids`` and ``ec2_security_group_names`` are comma-separated lists of all security groups. Each EC2 tag is a variable in the format ``ec2_tag_KEY``.
To see the complete list of variables available for an instance, run the script by itself::
cd plugins/inventory
./ec2.py --host ec2-12-12-12-12.compute-1.amazonaws.com
Example: OpenStack Inventory Script
```````````````````````````````````
Though not detailed here in as much depth as the EC2 module, there's also a OpenStack Compute external inventory source in the plugins directory. It requires the Grizzly release of OpenStack or
later. See the inline comments in the module source for how to use it.
Callback Plugins
----------------
Ansible can be configured via code to respond to external events. This can include enhancing logging, signalling an external software
system, or even (yes, really) making sound effects. Some examples are contained in the plugins directory.
Connection Type Plugins
-----------------------
By default, ansible ships with a 'paramiko' SSH, native ssh (just called 'ssh'), and 'local' connection type, and an accelerated connection type named 'fireball'. All of these can be used
in playbooks and with /usr/bin/ansible to decide how you want to talk to remote machines. The basics of these connection types
are covered in the 'getting started' section. Should you want to extend Ansible to support other transports (SNMP? Message bus?
Carrier Pigeon?) it's as simple as copying the format of one of the existing modules and dropping it into the connection plugins
directory. The value of 'smart' for a connection allows selection of paramiko or openssh based on system capabilities, and chooses
'ssh' if OpenSSH supports ControlPersist, in Ansible 1.2.1 an later. Previous versions did not support 'smart'.
Lookup Plugins
--------------
Language constructs like "with_fileglob" and "with_items" are implemented via lookup plugins. Just like other plugin types, you can write your own.
Vars Plugins
------------
Playbook constructs like 'host_vars' and 'group_vars' work via 'vars' plugins. They inject additional variable
data into ansible runs that did not come from an inventory, playbook, or command line. Note that variables
can also be returned from inventory, so in most cases, you won't need to write or understand vars_plugins.
Filter Plugins
--------------
If you want more Jinja2 filters available in a Jinja2 template (filters like to_yaml and to_json are provided by default), they can be extended by writing a filter plugin.
Distributing Plugins
--------------------
.. versionadded:: 0.8
Plugins are loaded from both Python's site_packages (those that ship with ansible) and a configured plugins directory, which defaults
to /usr/share/ansible/plugins, in a subfolder for each plugin type::
* action_plugins
* lookup_plugins
* callback_plugins
* connection_plugins
* filter_plugins
* vars_plugins
To change this path, edit the ansible configuration file.
In addition, plugins can be shipped in a subdirectory relative to a top-level playbook, in folders named the same as indicated above.
.. seealso::
:doc:`modules`
List of built-in modules
`Mailing List <http://groups.google.com/group/ansible-project>`_
Questions? Help? Ideas? Stop by the list on Google Groups
`irc.freenode.net <http://irc.freenode.net>`_
#ansible IRC chat channel

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API & Integrations
==================
There are several interesting ways to use Ansible from an API perspective. You can use
the Ansible python API to control nodes, you can extend Ansible to respond to various python events,
and you can plug in inventory data from external data sources. Ansible is written in its own
API so you have a considerable amount of power across the board.
.. contents:: `Table of contents`
:depth: 2
Python API
----------
The Python API is very powerful, and is how the ansible CLI and ansible-playbook
are implemented.
It's pretty simple::
import ansible.runner
runner = ansible.runner.Runner(
module_name='ping',
module_args='',
pattern='web*',
forks=10
)
datastructure = runner.run()
The run method returns results per host, grouped by whether they
could be contacted or not. Return types are module specific, as
expressed in the 'ansible-modules' documentation.::
{
"dark" : {
"web1.example.com" : "failure message"
},
"contacted" : {
"web2.example.com" : 1
}
}
A module can return any type of JSON data it wants, so Ansible can
be used as a framework to rapidly build powerful applications and scripts.
Detailed API Example
````````````````````
The following script prints out the uptime information for all hosts::
#!/usr/bin/python
import ansible.runner
import sys
# construct the ansible runner and execute on all hosts
results = ansible.runner.Runner(
pattern='*', forks=10,
module_name='command', module_args='/usr/bin/uptime',
).run()
if results is None:
print "No hosts found"
sys.exit(1)
print "UP ***********"
for (hostname, result) in results['contacted'].items():
if not 'failed' in result:
print "%s >>> %s" % (hostname, result['stdout'])
print "FAILED *******"
for (hostname, result) in results['contacted'].items():
if 'failed' in result:
print "%s >>> %s" % (hostname, result['msg'])
print "DOWN *********"
for (hostname, result) in results['dark'].items():
print "%s >>> %s" % (hostname, result)
Advanced programmers may also wish to read the source to ansible itself, for
it uses the Runner() API (with all available options) to implement the
command line tools ``ansible`` and ``ansible-playbook``.
Plugins Available Online
------------------------
The remainder of features in the API docs have components available in `ansible-plugins <https://github.com/ansible/ansible/blob/devel/plugins>`_. Send us a github pull request if you develop any interesting features.
External Inventory Scripts
--------------------------
Often a user of a configuration management system will want to keep inventory
in a different system. Frequent examples include LDAP, `Cobbler <http://cobbler.github.com>`_,
or a piece of expensive enterprisey CMDB software. Ansible easily supports all
of these options via an external inventory system. The plugins directory contains some of these already -- including options for EC2/Eucalyptus and OpenStack, which will be detailed below.
It's possible to write an external inventory script in any language. If you are familiar with Puppet terminology, this concept is basically the same as 'external nodes', with the slight difference that it also defines which hosts are managed.
Script Conventions
``````````````````
When the external node script is called with the single argument '--list', the script must return a JSON hash/dictionary of all the groups to be managed.
Each group's value should be either a hash/dictionary containing a list of each host/IP, potential child groups, and potential group variables, or
simply a list of host/IP addresses, like so::
{
"databases" : {
"hosts" : [ "host1.example.com", "host2.example.com" ],
"vars" : {
"a" : true
}
},
"webservers" : [ "host2.example.com", "host3.example.com" ],
"atlanta" : {
"hosts" : [ "host1.example.com", "host4.example.com", "host5.example.com" ],
"vars" : {
"b" : false
},
"children": [ "marietta", "5points" ],
},
"marietta" : [ "host6.example.com" ],
"5points" : [ "host7.example.com" ]
}
.. versionadded:: 1.0
Before version 1.0, each group could only have a list of hostnames/IP addresses, like the webservers, marietta, and 5points groups above.
When called with the arguments '--host <hostname>' (where <hostname> is a host from above), the script must return either an empty JSON
hash/dictionary, or a hash/dictionary of variables to make available to templates and playbooks. Returning variables is optional,
if the script does not wish to do this, returning an empty hash/dictionary is the way to go::
{
"favcolor" : "red",
"ntpserver" : "wolf.example.com",
"monitoring" : "pack.example.com"
}
Tuning the External Inventory Script
````````````````````````````````````
.. versionadded:: 1.3
The stock inventory script system detailed above works for all versions of Ansible, but calling
'--host' for every host can be rather expensive, especially if it involves expensive API calls to
a remote subsystemm. In Ansible
1.3 or later, if the inventory script returns a top level element called "_meta", it is possible
to return all of the host variables in one inventory script call. When this meta element contains
a value for "hostvars", the inventory script will not be invoked with "--host" for each host. This
results in a significant performance increase for large numbers of hosts, and also makes client
side caching easier to implement for the inventory script.
The data to be added to the top level JSON dictionary looks like this::
{
# results of inventory script as above go here
# ...
"_meta" : {
"hostvars" : {
"moocow.example.com" : { "asdf" : 1234 },
"llama.example.com" : { "asdf" : 5678 },
}
}
}
Example: The Cobbler External Inventory Script
``````````````````````````````````````````````
It is expected that many Ansible users will also be `Cobbler <http://cobbler.github.com>`_ users. Cobbler has a generic
layer that allows it to represent data for multiple configuration management systems (even at the same time), and has
been referred to as a 'lightweight CMDB' by some admins. This particular script will communicate with Cobbler
using Cobbler's XMLRPC API.
To tie Ansible's inventory to Cobbler (optional), copy `this script <https://raw.github.com/ansible/ansible/devel/plugins/inventory/cobbler.py>`_ to /etc/ansible/hosts and `chmod +x` the file. cobblerd will now need
to be running when you are using Ansible.
Test the file by running `./etc/ansible/hosts` directly. You should see some JSON data output, but it may not have
anything in it just yet.
Let's explore what this does. In cobbler, assume a scenario somewhat like the following::
cobbler profile add --name=webserver --distro=CentOS6-x86_64
cobbler profile edit --name=webserver --mgmt-classes="webserver" --ksmeta="a=2 b=3"
cobbler system edit --name=foo --dns-name="foo.example.com" --mgmt-classes="atlanta" --ksmeta="c=4"
cobbler system edit --name=bar --dns-name="bar.example.com" --mgmt-classes="atlanta" --ksmeta="c=5"
In the example above, the system 'foo.example.com' will be addressable by ansible directly, but will also be addressable when using the group names 'webserver' or 'atlanta'. Since Ansible uses SSH, we'll try to contract system foo over 'foo.example.com', only, never just 'foo'. Similarly, if you try "ansible foo" it wouldn't find the system... but "ansible 'foo*'" would, because the system DNS name starts with 'foo'.
The script doesn't just provide host and group info. In addition, as a bonus, when the 'setup' module is run (which happens automatically when using playbooks), the variables 'a', 'b', and 'c' will all be auto-populated in the templates::
# file: /srv/motd.j2
Welcome, I am templated with a value of a={{ a }}, b={{ b }}, and c={{ c }}
Which could be executed just like this::
ansible webserver -m setup
ansible webserver -m template -a "src=/tmp/motd.j2 dest=/etc/motd"
.. note::
The name 'webserver' came from cobbler, as did the variables for
the config file. You can still pass in your own variables like
normal in Ansible, but variables from the external inventory script
will override any that have the same name.
So, with the template above (motd.j2), this would result in the following data being written to /etc/motd for system 'foo'::
Welcome, I am templated with a value of a=2, b=3, and c=4
And on system 'bar' (bar.example.com)::
Welcome, I am templated with a value of a=2, b=3, and c=5
And technically, though there is no major good reason to do it, this also works too::
ansible webserver -m shell -a "echo {{ a }}"
So in other words, you can use those variables in arguments/actions as well. You might use this to name
a conf.d file appropriately or something similar. Who knows?
So that's the Cobbler integration support -- using the cobbler script as an example, it should be trivial to adapt Ansible to pull inventory, as well as variable information, from any data source. If you create anything interesting, please share with the mailing list, and we can keep it in the source code tree for others to use.
Example: AWS EC2 External Inventory Script
``````````````````````````````````````````
If you use Amazon Web Services EC2, maintaining an inventory file might not be the best approach. For this reason, you can use the `EC2 external inventory <https://raw.github.com/ansible/ansible/devel/plugins/inventory/ec2.py>`_ script.
You can use this script in one of two ways. The easiest is to use Ansible's ``-i`` command line option and specify the path to the script.
ansible -i ec2.py -u ubuntu us-east-1d -m ping
The second option is to copy the script to `/etc/ansible/hosts` and `chmod +x` it. You will also need to copy the `ec2.ini <https://raw.github.com/ansible/ansible/devel/plugins/inventory/ec2.ini>`_ file to `/etc/ansible/ec2.ini`. Then you can run ansible as you would normally.
To successfully make an API call to AWS, you will need to configure Boto (the Python interface to AWS). There are a `variety of methods <http://docs.pythonboto.org/en/latest/boto_config_tut.html>`_ available, but the simplest is just to export two environment variables:
export AWS_ACCESS_KEY_ID='AK123'
export AWS_SECRET_ACCESS_KEY='abc123'
You can test the script by itself to make sure your config is correct
cd plugins/inventory
./ec2.py --list
After a few moments, you should see your entire EC2 inventory across all regions in JSON.
Since each region requires its own API call, if you are only using a small set of regions, feel free to edit ``ec2.ini`` and list only the regions you are interested in. There are other config options in ``ec2.ini`` including cache control, and destination variables.
At their heart, inventory files are simply a mapping from some name to a destination address. The default ``ec2.ini`` settings are configured for running Ansible from outside EC2 (from your laptop for example). If you are running Ansible from within EC2, internal DNS names and IP addresses may make more sense than public DNS names. In this case, you can modify the ``destination_variable`` in ``ec2.ini`` to be the private DNS name of an instance. This is particularly important when running Ansible within a private subnet inside a VPC, where the only way to access an instance is via its private IP address. For VPC instances, `vpc_destination_variable` in ``ec2.ini`` provides a means of using which ever `boto.ec2.instance variable <http://docs.pythonboto.org/en/latest/ref/ec2.html#module-boto.ec2.instance>`_ makes the most sense for your use case.
The EC2 external inventory provides mappings to instances from several groups:
Instance ID
These are groups of one since instance IDs are unique.
e.g.
``i-00112233``
``i-a1b1c1d1``
Region
A group of all instances in an AWS region.
e.g.
``us-east-1``
``us-west-2``
Availability Zone
A group of all instances in an availability zone.
e.g.
``us-east-1a``
``us-east-1b``
Security Group
Instances belong to one or more security groups. A group is created for each security group, with all characters except alphanumerics, dashes (-) converted to underscores (_). Each group is prefixed by ``security_group_``
e.g.
``security_group_default``
``security_group_webservers``
``security_group_Pete_s_Fancy_Group``
Tags
Each instance can have a variety of key/value pairs associated with it called Tags. The most common tag key is 'Name', though anything is possible. Each key/value pair is its own group of instances, again with special characters converted to underscores, in the format ``tag_KEY_VALUE``
e.g.
``tag_Name_Web``
``tag_Name_redis-master-001``
``tag_aws_cloudformation_logical-id_WebServerGroup``
When the Ansible is interacting with a specific server, the EC2 inventory script is called again with the ``--host HOST`` option. This looks up the HOST in the index cache to get the instance ID, and then makes an API call to AWS to get information about that specific instance. It then makes information about that instance available as variables to your playbooks. Each variable is prefixed by ``ec2_``. Here are some of the variables available:
- ec2_architecture
- ec2_description
- ec2_dns_name
- ec2_id
- ec2_image_id
- ec2_instance_type
- ec2_ip_address
- ec2_kernel
- ec2_key_name
- ec2_launch_time
- ec2_monitored
- ec2_ownerId
- ec2_placement
- ec2_platform
- ec2_previous_state
- ec2_private_dns_name
- ec2_private_ip_address
- ec2_public_dns_name
- ec2_ramdisk
- ec2_region
- ec2_root_device_name
- ec2_root_device_type
- ec2_security_group_ids
- ec2_security_group_names
- ec2_spot_instance_request_id
- ec2_state
- ec2_state_code
- ec2_state_reason
- ec2_status
- ec2_subnet_id
- ec2_tag_Name
- ec2_tenancy
- ec2_virtualization_type
- ec2_vpc_id
Both ``ec2_security_group_ids`` and ``ec2_security_group_names`` are comma-separated lists of all security groups. Each EC2 tag is a variable in the format ``ec2_tag_KEY``.
To see the complete list of variables available for an instance, run the script by itself::
cd plugins/inventory
./ec2.py --host ec2-12-12-12-12.compute-1.amazonaws.com
Example: OpenStack Inventory Script
```````````````````````````````````
Though not detailed here in as much depth as the EC2 module, there's also a OpenStack Compute external inventory source in the plugins directory. It requires the Grizzly release of OpenStack or
later. See the inline comments in the module source for how to use it.
Callback Plugins
----------------
Ansible can be configured via code to respond to external events. This can include enhancing logging, signalling an external software
system, or even (yes, really) making sound effects. Some examples are contained in the plugins directory.
Connection Type Plugins
-----------------------
By default, ansible ships with a 'paramiko' SSH, native ssh (just called 'ssh'), and 'local' connection type, and an accelerated connection type named 'fireball'. All of these can be used
in playbooks and with /usr/bin/ansible to decide how you want to talk to remote machines. The basics of these connection types
are covered in the 'getting started' section. Should you want to extend Ansible to support other transports (SNMP? Message bus?
Carrier Pigeon?) it's as simple as copying the format of one of the existing modules and dropping it into the connection plugins
directory. The value of 'smart' for a connection allows selection of paramiko or openssh based on system capabilities, and chooses
'ssh' if OpenSSH supports ControlPersist, in Ansible 1.2.1 an later. Previous versions did not support 'smart'.
Lookup Plugins
--------------
Language constructs like "with_fileglob" and "with_items" are implemented via lookup plugins. Just like other plugin types, you can write your own.
Vars Plugins
------------
Playbook constructs like 'host_vars' and 'group_vars' work via 'vars' plugins. They inject additional variable
data into ansible runs that did not come from an inventory, playbook, or command line. Note that variables
can also be returned from inventory, so in most cases, you won't need to write or understand vars_plugins.
Filter Plugins
--------------
If you want more Jinja2 filters available in a Jinja2 template (filters like to_yaml and to_json are provided by default), they can be extended by writing a filter plugin.
Distributing Plugins
--------------------
.. versionadded:: 0.8
Plugins are loaded from both Python's site_packages (those that ship with ansible) and a configured plugins directory, which defaults
to /usr/share/ansible/plugins, in a subfolder for each plugin type::
* action_plugins
* lookup_plugins
* callback_plugins
* connection_plugins
* filter_plugins
* vars_plugins
To change this path, edit the ansible configuration file.
In addition, plugins can be shipped in a subdirectory relative to a top-level playbook, in folders named the same as indicated above.
.. seealso::
:doc:`modules`
List of built-in modules
`Mailing List <http://groups.google.com/group/ansible-project>`_
Questions? Help? Ideas? Stop by the list on Google Groups
`irc.freenode.net <http://irc.freenode.net>`_
#ansible IRC chat channel

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Ansible Documentation Index Ansible Documentation
``````````````````````````` `````````````````````
Welcome to the Ansible documentation.
Welcome to the Ansible documentation. This documentation covers the current released Ansible is an IT automation tool. It can configure systems, deploy software, and orchestrate more advanced IT orchestration
version of Ansible (1.2) and may also reference some development version features. such as continuous deployments or zero downtime rolling updates.
For the previous released version, see `Ansible 1.1 Docs <http://ansibleworks.com/docs/released/1.1>`_ instead. Ansibe's goals are foremost those of simplicity and ease of use. It also has a strong focus on security and reliability, featuring
a minimum of moving parts, usage of Open SSH for transport, and a language that is designed around auditability by humans -- even those
not familiar with the program.
This documentation covers the current released version of Ansible (1.3.X) and also some development version features (1.4). For recent features, in each section, the version of Ansible where the feature is added is indicated. Ansible produces a new major release approximately
every 2 months.
Before we dive into playbooks, configuration management, deployment, and orchestration, we'll learn how to get Ansible installed and some Before we dive into playbooks, configuration management, deployment, and orchestration, we'll learn how to get Ansible installed and some
basic information. We'll go over how to execute ad-hoc commands in parallel across your nodes using /usr/bin/ansible. We'll also see basic information. We'll go over how to execute ad-hoc commands in parallel across your nodes using /usr/bin/ansible. We'll also see
what sort of modules are available in Ansible's core (though you can also write your own, which we'll also show later). what sort of modules are available in Ansible's core (though you can also write your own, which we'll also show later).
An Introduction
```````````````
.. toctree:: .. toctree::
:maxdepth: 1 :maxdepth: 1
gettingstarted intro_installation
patterns intro_gettingstarted
examples intro_inventory
intro_inventory_dynamic
intro_patterns
intro_adhoc
modules modules
Overview Overview
@ -28,56 +41,98 @@ Overview
:width: 788px :width: 788px
:height: 436px :height: 436px
An Introduction to Playbooks
````````````````````````````
Playbooks Playbooks are Ansible's configuration, deployment, and orchestration language. They can describe a policy you want your remote systems
````````` to enforce, or a set of steps in a general IT process.
Playbooks are Ansible's orchestration language. At a basic level, playbooks can be used to manage configurations and deployments At a basic level, playbooks can be used to manage configurations of and deployments to remote machines. At a more advanced level, they can sequence multi-tier rollouts involving rolling updates, and can delegate actions to other hosts, interacting with monitoring servers and load balancers along the way.
of remote machines. At a more advanced level, they can sequence multi-tier rollouts involving rolling updates, and can delegate actions
to other hosts, interacting with monitoring servers and load balancers along the way. You can start small and pick up more features There's no need to learn everything at once. You can start small and pick up more features
over time as you need them. Playbooks are designed to be human-readable and are developed in a basic text language. There are multiple over time as you need them.
Playbooks are designed to be human-readable and are developed in a basic text language. There are multiple
ways to organize playbooks and the files they include, and we'll offer up some suggestions on that and making the most out of Ansible. ways to organize playbooks and the files they include, and we'll offer up some suggestions on that and making the most out of Ansible.
.. toctree:: .. toctree::
:maxdepth: 1 :maxdepth: 1
playbooks playbooks
playbooks2 playbooks_roles
bestpractices playbooks_variables
YAMLSyntax playbooks_facts
playbooks_loops
playbooks_best_practices
Example Playbooks <https://github.com/ansible/ansible-examples> Example Playbooks <https://github.com/ansible/ansible-examples>
Specific Solutions Special Topics In Playbooks
`````````````````` ```````````````````````````
Here are some playbook features that not everyone may need to learn, but can be quite useful for particular applications.
Browsing these topics is recommended as you may find some useful tips here, but feel free to learn Ansible first and adopt
these only if they seem relevant or useful to your environment.
playbooks_acceleration
playbooks_check_mode
playbooks_delegation
playbooks_environment
playbooks_error_handling
playbooks_lookups
playbooks_prompts
playbooks_strategies
Detailed Guides
```````````````
This section is new and evolving. The idea here is explore particular use cases in greater depth and provide a more "top down" explanation
of some basic features.
A chance to dive into some more topics in depth: A chance to dive into some more topics in depth:
.. toctree:: .. toctree::
:maxdepth: 1 :maxdepth: 1
amazon_web_services guide_aws
Pending topics may include: Vagrant, Docker, Jenkins, Rackspace Cloud, Google Compute Engine, Linode/Digital Ocean, Continous Deployment,
and more.
Community Information
`````````````````````
Ansible is an open source project designed to bring together developers and administrators of all kinds to collaborate on building
IT automation solutions that work well for them. Should you wish to get more involved -- whether in terms of just asking a question, helping
other users, introducing new people to Ansible, or helping with the software or documentation, we welcome your contributions to the project.
How to interact <https://github.com/ansible/ansible/blob/devel/CONTRIBUTING.md>
Developer Information Developer Information
````````````````````` `````````````````````
Learn how to build modules of your own in any language. Explore Ansible's Python API and write Python plugins to integrate Learn how to build modules of your own in any language, and also how to extend ansible through several kinds of plugins. Explore Ansible's Python API and write Python plugins to integrate
with other solutions in your environment. with other solutions in your environment.
.. toctree:: .. toctree::
:maxdepth: 1 :maxdepth: 1
api developers_contributing
moduledev developers_code_standards
developers_api
developers_inventory
developers_modules
developers_plugins
developers_callbacks
developers_filters
developers_lookups
developers_transports
developers_modules
REST API <http://ansibleworks.com/ansibleworks-awx>
Miscellaneous Miscellaneous
````````````` `````````````
`Learn and share neat Ansible tricks on Coderwall <https://coderwall.com/p/t/ansible>`_ - sign-in using GitHub or Twitter to vote on top tips and add your own!
`A list of some Ansible users and quotes about Ansible <http://www.ansibleworks.com/users>`_.
More links:
.. toctree:: .. toctree::
:maxdepth: 1 :maxdepth: 1

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Getting Started
===============
.. contents::
:depth: 2
Requirements
````````````
Requirements for Ansible are extremely minimal.
For the central Ansible machine, you will need an environment with Python 2.6 or greater installed. If you are running Python 2.5 on an "Enterprise Linux 5" variant, we'll show you how to add 2.6 to your distribution, but most platforms already have a new enough Python. (Note that Windows is not supported as the Ansible control machine.)
You will also want the following Python modules (installed via pip or perhaps via your OS package manager via slightly different names):
* ``paramiko``
* ``PyYAML``
* ``jinja2``
If you are using RHEL or CentOS 5, Python is version 2.4 by default, but you can get Python 2.6 installed easily. `Use EPEL <http://fedoraproject.org/wiki/EPEL>`_ and install these dependencies as follows:
.. code-block:: bash
$ yum install python26 python26-PyYAML python26-paramiko python26-jinja2
On the managed nodes, you only need Python 2.4 or later, but if you are are running less than Python 2.6 on them, you will
also need:
* ``python-simplejson``
.. note::
Ansible's "raw" module (for executing commands in a quick and dirty
way) and the script module don't even need that. So technically, you can use
Ansible to install python-simplejson using the raw module, which
then allows you to use everything else. (That's jumping ahead
though.)
.. note::
If you have SELinux enabled on remote nodes, you will also want to install
libselinux-python on them before using any copy/file/template related functions in
Ansible. You can of course still use the yum module in Ansible to install this package on
remote systems that do not have it.
.. note::
Python 3 is a slightly different language than Python 2 and most python programs (including
Ansible) are not switching over yet. However, some Linux distributions (Gentoo, Arch) may not have a
Python 2.X interpreter installed by default. On those systems, you should install one, and set
the 'ansible_python_interpreter' variable in inventory (see :doc:`patterns`) to point at your 2.X python. Distributions
like Red Hat Enterprise Linux, CentOS, Fedora, and Ubuntu all have a 2.X interpreter installed
by default and this does not apply to those distributions. This is also true of nearly all
Unix systems. If you need to bootstrap these remote systems by installing Python 2.X,
using the 'raw' module will be able to do it remotely.
Getting Ansible
```````````````
If you are interested in using all the latest features, you may wish to keep up to date
with the development branch of the git checkout. This also makes it easiest to contribute
back to the project.
Instructions for installing from source are below.
Ansible's release cycles are usually about two months long. Due to this
short release cycle, minor bugs will generally be fixed in the next release versus maintaining
backports on the stable branch.
You may also wish to follow the `Github project <https://github.com/ansible/ansible>`_ if
you have a github account. This is also where we keep the issue tracker for sharing
bugs and feature ideas.
Running From Checkout
+++++++++++++++++++++
Ansible is trivially easy to run from a checkout, root permissions are not required
to use it:
.. code-block:: bash
$ git clone git://github.com/ansible/ansible.git
$ cd ./ansible
$ source ./hacking/env-setup
You will want to install the dependencies needed by Ansible with pip if going from a checkout::
# on Ubuntu, for example:
apt-get install python-dev python-pip
pip install PyYAML Jinja2 paramiko
Once running the env-setup script you'll be running from checkout and the default inventory file
will be /etc/ansible/hosts. You can optionally specify an inventory file (see :doc:`patterns`)
other than /etc/ansible/hosts:
.. code-block:: bash
$ echo "127.0.0.1" > ~/ansible_hosts
$ export ANSIBLE_HOSTS=~/ansible_hosts
You can read more about the inventory file in later parts of the manual.
Now let's test things:
.. code-block:: bash
$ ansible all -m ping --ask-pass
Make Install
++++++++++++
If you are not working from a distribution where Ansible is packaged yet, you can install Ansible
using "make install". This is done through `python-distutils`:
.. code-block:: bash
$ git clone git://github.com/ansible/ansible.git
$ cd ./ansible
$ sudo make install
Via Pip
+++++++
Are you a python developer?
Ansible can be installed via Pip, but when you do so, it will ask to install other dependencies used for
things like 'fireball' mode that you might not need::
$ sudo easy_install pip
$ sudo pip install ansible
Readers that use virtualenv can also install Ansible under virtualenv. Do not use easy_install to install
ansible directly.
Via RPM
+++++++
RPMs for the last Ansible release are available for `EPEL
<http://fedoraproject.org/wiki/EPEL>`_ 6 and currently supported
Fedora distributions. RPMs for openSUSE can be found via the
`openSUSE Software Portal <http://software.opensuse.org/package/ansible>`_
(in the systemsmanagement Project) for all currently supported
openSUSE and SLES distributions.
Ansible itself can manage earlier operating
systems that contain python 2.4 or higher.
If you are using RHEL or CentOS and have not already done so, `configure EPEL <http://fedoraproject.org/wiki/EPEL>`_
.. code-block:: bash
# install the epel-release RPM if needed on CentOS, RHEL, or Scientific Linux
$ sudo yum install ansible
For openSUSE and SUSE Linux Enterprise, add the `systemsmanagement repository <http://download.opensuse.org/repositories/systemsmanagement/>`_
for your distribution:
.. code-block:: bash
# replace $dist with the correct distribution found here: http://download.opensuse.org/repositories/systemsmanagement/
$ sudo zypper ar -f http://download.opensuse.org/repositories/systemsmanagement/$dist/systemsmanagement.repo
$ sudo zypper install ansible
You can also use the ``make rpm`` command to build an RPM you can distribute and install.
Make sure you have ``rpm-build``, ``make``, and ``python2-devel`` installed.
.. code-block:: bash
$ git clone git://github.com/ansible/ansible.git
$ cd ./ansible
$ make rpm
$ sudo rpm -Uvh ~/rpmbuild/ansible-*.noarch.rpm
Via MacPorts on OS X
++++++++++++++++++++
Ansible is easily run or installed from source, but you can also use MacPorts.
To install the stable version of Ansible from MacPorts, run:
.. code-block:: bash
$ sudo port install ansible
If you wish to install the latest build via the MacPorts system from a
git checkout, run:
.. code-block:: bash
$ git clone git://github.com/ansible/ansible.git
$ cd ./ansible/packaging/macports
$ sudo port install
Please refer to the documentation at <http://www.macports.org> for
further information on using Portfiles with MacPorts.
Ubuntu and Debian
+++++++++++++++++
Ubuntu builds are available `in a PPA here <https://launchpad.net/~rquillo/+archive/ansible>`_.
Once configured,
.. code-block:: bash
$ sudo apt-get install ansible
Debian/Ubuntu packages can also be built from the source checkout, run:
.. code-block:: bash
$ make debian
You may also wish to run from source to get the latest, which is covered above.
Gentoo, Arch, Others
++++++++++++++++++++
Gentoo eBuilds are in portage, version 1.0 `coming soon <https://bugs.gentoo.org/show_bug.cgi?id=461830>`_.
.. code-block:: bash
$ emerge ansible
An Arch PKGBUILD is available on `AUR <https://aur.archlinux.org/packages.php?ID=58621>`_
If you have python3 installed on Arch, you probably want to symlink python to python2:
.. code-block:: bash
$ sudo ln -sf /usr/bin/python2 /usr/bin/python
You should also set a 'ansible_python_interpreter' inventory variable (see :doc:`patterns`) for hosts that have python
pointing to python3, so the right python can be found on the managed nodes.
Tagged Releases
+++++++++++++++
Tarballs of releases are available on the ansibleworks.com page.
* `Ansible/downloads <http://ansibleworks.com/releases>`_
These releases are also tagged in the git repository with the release version.
Choosing Between Paramiko and Native SSH
````````````````````````````````````````
By default, ansible 1.3 and later will try to use native SSH for remote communication when possible.
This is done when ControlPersist support is available. Paramiko is however reasonably fast and makes
a good default on versions of Enterprise Linux where ControlPersist is not available. However, Paramiko
does not support some advanced SSH features that folks will want to use. In Ansible 1.2 and before,
the default was strictly paramiko and native SSH had to be explicitly selected with -c ssh or set in the
configuration file.
.. versionadded:: 0.5
If you want to leverage more advanced SSH features (such as Kerberized
SSH or jump hosts), pass the flag "--connection=ssh" to any ansible
command, or set the ANSIBLE_TRANSPORT environment variable to
'ssh'. This will cause Ansible to use openssh tools instead.
If ANSIBLE_SSH_ARGS are not set, ansible will try to use some sensible ControlMaster options
by default. You are free to override this environment variable, but should still pass ControlMaster
options to ensure performance of this transport. With ControlMaster in use, both transports
are roughly the same speed. Without CM, the binary ssh transport is signficantly slower.
If none of this makes sense to you, the default paramiko option is probably fine.
Your first commands
```````````````````
Now that you've installed Ansible, it's time to test it.
Edit (or create) /etc/ansible/hosts and put one or more remote systems in it, for
which you have your SSH key in ``authorized_keys``::
192.168.1.50
aserver.example.org
bserver.example.org
Set up SSH agent to avoid retyping passwords:
.. code-block:: bash
$ ssh-agent bash
$ ssh-add ~/.ssh/id_rsa
(Depending on your setup, you may wish to ansible's --private-key option to specify a pem file instead)
Now ping all your nodes:
.. code-block:: bash
$ ansible all -m ping
Ansible will attempt to remote connect to the machines using your current
user name, just like SSH would. To override the remote user name, just use the '-u' parameter.
If you would like to access sudo mode, there are also flags to do that:
.. code-block:: bash
# as bruce
$ ansible all -m ping -u bruce
# as bruce, sudoing to root
$ ansible all -m ping -u bruce --sudo
# as bruce, sudoing to batman
$ ansible all -m ping -u bruce --sudo --sudo-user batman
(The sudo implementation is changeable in ansible's configuration file if you happen to want to use a sudo
replacement. Flags passed dot sudo can also be set.)
Now run a live command on all of your nodes:
.. code-block:: bash
$ ansible all -a "/bin/echo hello"
Congratulations. You've just contacted your nodes with Ansible. It's
soon going to be time to read some of the more real-world :doc:`examples`, and explore
what you can do with different modules, as well as the Ansible
:doc:`playbooks` language. Ansible is not just about running commands, it
also has powerful configuration management and deployment features. There's more to
explore, but you already have a fully working infrastructure!
A note about Connection (Transport) Modes
`````````````````````````````````````````
Ansible has two major forms of SSH transport implemented, 'ssh' (OpenSSH) and 'paramiko'. Paramiko is a python
SSH implementation and 'ssh' simply calls OpenSSH behind the scenes. There are additionally 'fireball' (an accelerated
remote transport), 'local', and 'chroot' connection modes in Ansible that don't use SSH, but connecting by one of the two
SSH transports is the most common way to manage systems. It is useful to understand the difference between the 'ssh'
and 'paramiko' modes.
Paramiko is provided because older Enterprise Linux operating systems do not have an efficient OpenSSH that support
ControlPersist technology, and in those cases, 'paramiko' is faster than 'ssh'. Thus, until EL6 backports a newer
SSH, 'paramiko' is the faster option on that platform.
However, if you have a newer 'ssh' that supports ControlPersist, usage of the 'ssh' transport unlocks additional
configurability, including the option to use Kerberos. For instance, the latest Fedora and Ubuntu releases
all offer a sufficiently new OpenSSH. With ControlPersist available, 'ssh' is usually about as fast as paramiko.
If you'd like even more speed, read about 'fireball' in the Advanced Playbooks section.
Starting with Ansible 1.2.1, the default transport mode for Ansible is 'smart', which means it will detect
if OpenSSH supports ControlPersist, and will select 'ssh' if available, and otherwise pick 'paramiko'.
Previous versions of Ansible defaulted to 'paramiko'.
A note about Host Key Checking
``````````````````````````````
Ansible 1.2.1 and later have host key checking enabled by default.
If a host is reinstalled and has a different key in 'known_hosts', this will result in a error message until
corrected. If a host is not initially in 'known_hosts' this will result in prompting for confirmation of the key,
which results in a interactive experience if using Ansible, from say, cron.
If you wish to disable this behavior and understand the implications, you can do so by editing /etc/ansible/ansible.cfg or ~/.ansible.cfg::
[defaults]
host_key_checking = False
Alternatively this can be set by an environment variable:
$ export ANSIBLE_HOST_KEY_CHECKING=False
Also note that host key checking in paramiko mode is reasonably slow, therefore switching to 'ssh' is also recommended when using this
feature.
.. seealso::
:doc:`examples`
Examples of basic commands
:doc:`playbooks`
Learning ansible's configuration management language
`Mailing List <http://groups.google.com/group/ansible-project>`_
Questions? Help? Ideas? Stop by the list on Google Groups
`irc.freenode.net <http://irc.freenode.net>`_
#ansible IRC chat channel

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.. _patterns:
Inventory & Patterns
====================
Ansible works against multiple systems in your infrastructure at the
same time. It does this by selecting portions of systems listed in
Ansible's inventory file, which defaults to /etc/ansible/hosts.
.. contents::
:depth: 2
.. _inventoryformat:
Hosts and Groups
++++++++++++++++
The format for /etc/ansible/hosts is an INI format and looks like this::
mail.example.com
[webservers]
foo.example.com
bar.example.com
[dbservers]
one.example.com
two.example.com
three.example.com
The things in brackets are group names. You don't have to have them,
but they are useful.
If you have hosts that run on non-standard SSH ports you can put the port number
after the hostname with a colon. Ports listed in any SSH config file won't be read,
so it is important that you set them if things are not running on the default port::
badwolf.example.com:5309
Suppose you have just static IPs and want to set up some aliases that don't live in your host file, or you are connecting through tunnels. You can do things like this::
jumper ansible_ssh_port=5555 ansible_ssh_host=192.168.1.50
In the above example, trying to ansible against the host alias "jumper" (which may not even be a real hostname) will contact 192.168.1.50 on port 5555.
Adding a lot of hosts? In 0.6 and later, if you have a lot of hosts following similar patterns you can do this rather than listing each hostname::
[webservers]
www[01:50].example.com
In 1.0 and later, you can also do this for alphabetic ranges::
[databases]
db-[a:f].example.com
For numeric patterns, leading zeros can be included or removed, as desired. Ranges are inclusive.
In 1.1 and later, you can also select the connection type and user on a per host basis::
[targets]
localhost ansible_connection=local
other1.example.com ansible_connection=ssh ansible_ssh_user=mpdehaan
other2.example.com ansible_connection=ssh ansible_ssh_user=mdehaan
All of these variables can of course also be set outside of the inventory file, in 'host_vars' if you wish
to keep your inventory file simple.
List of Reserved Inventory Parameters
+++++++++++++++++++++++++++++++++++++
As a summary, you can set these parameters as host inventory variables. (Some we have already
mentioned).
ansible_ssh_host
The name of the host to connect to, if different from the alias you wish to give to it.
ansible_ssh_port
The ssh port number, if not 22
ansible_ssh_user
The default ssh user name to use.
ansible_ssh_pass
The ssh password to use (this is insecure, we strongly recommend using --ask-pass or SSH keys)
ansible_connection
Connection type of the host. Candidates are local, ssh or paramiko. The default is paramiko before Ansible 1.2, and 'smart' afterwards which detects whether usage of 'ssh' would be feasible based on whether ControlPersist is supported.
ansible_ssh_private_key_file
Private key file used by ssh. Useful if using multiple keys and you don't want to use SSH agent.
ansible_syslog_facility
The syslog facility to log to.
ansible_python_interpreter
The target host python path. This is userful for systems with more
than one Python or not located at "/usr/bin/python" such as \*BSD, or where /usr/bin/python
is not a 2.X series Python.
ansible\_\*\_interpreter
Works for anything such as ruby or perl and works just like ansible_python_interpreter.
This replaces shebang of modules which will run on that host.
Examples from a host file::
some_host ansible_ssh_port=2222 ansible_ssh_user=manager
aws_host ansible_ssh_private_key_file=/home/example/.ssh/aws.pem
freebsd_host ansible_python_interpreter=/usr/local/bin/python
ruby_module_host ansible_ruby_interpreter=/usr/bin/ruby.1.9.3
Selecting Targets
+++++++++++++++++
We'll go over how to use the command line in :doc:`examples` section, however, basically it looks like this::
ansible <pattern_goes_here> -m <module_name> -a <arguments>
Such as::
ansible webservers -m service -a "name=httpd state=restarted"
Within :doc:`playbooks`, these patterns can be used for even greater purposes.
Anyway, to use Ansible, you'll first need to know how to tell Ansible which hosts in your inventory file to talk to.
This is done by designating particular host names or groups of hosts.
The following patterns target all hosts in the inventory file::
all
*
Basically 'all' is an alias for '*'. It is also possible to address a specific host or hosts::
one.example.com
one.example.com:two.example.com
192.168.1.50
192.168.1.*
The following patterns address one or more groups, which are denoted
with the aforementioned bracket headers in the inventory file::
webservers
webservers:dbservers
You can exclude groups as well, for instance, all webservers not in Phoenix::
webservers:!phoenix
You can also specify the intersection of two groups::
webservers:&staging
You can do combinations::
webservers:dbservers:!phoenix:&staging
You can also use variables::
webservers:!{{excluded}}:&{{required}}
Individual host names, IPs and groups, can also be referenced using
wildcards::
*.example.com
*.com
It's also ok to mix wildcard patterns and groups at the same time::
one*.com:dbservers
And if the pattern starts with a '~' it is treated as a regular expression::
~(web|db).*\.example\.com
Easy enough. See :doc:`examples` and then :doc:`playbooks` for how to do things to selected hosts.
Host Variables
++++++++++++++
It is easy to assign variables to hosts that will be used later in playbooks::
[atlanta]
host1 http_port=80 maxRequestsPerChild=808
host2 http_port=303 maxRequestsPerChild=909
Group Variables
+++++++++++++++
Variables can also be applied to an entire group at once::
[atlanta]
host1
host2
[atlanta:vars]
ntp_server=ntp.atlanta.example.com
proxy=proxy.atlanta.example.com
Groups of Groups, and Group Variables
+++++++++++++++++++++++++++++++++++++
It is also possible to make groups of groups and assign
variables to groups. These variables can be used by /usr/bin/ansible-playbook, but not
/usr/bin/ansible::
[atlanta]
host1
host2
[raleigh]
host2
host3
[southeast:children]
atlanta
raleigh
[southeast:vars]
some_server=foo.southeast.example.com
halon_system_timeout=30
self_destruct_countdown=60
escape_pods=2
[usa:children]
southeast
northeast
southwest
southeast
If you need to store lists or hash data, or prefer to keep host and group specific variables
separate from the inventory file, see the next section.
Splitting Out Host and Group Specific Data
++++++++++++++++++++++++++++++++++++++++++
.. versionadded:: 0.6
In addition to the storing variables directly in the INI file, host
and group variables can be stored in individual files relative to the
inventory file. These variable files are in YAML format.
Assuming the inventory file path is::
/etc/ansible/hosts
If the host is named 'foosball', and in groups 'raleigh' and 'webservers', variables
in YAML files at the following locations will be made available to the host::
/etc/ansible/group_vars/raleigh
/etc/ansible/group_vars/webservers
/etc/ansible/host_vars/foosball
For instance, suppose you have hosts grouped by datacenter, and each datacenter
uses some different servers. The data in the groupfile '/etc/ansible/group_vars/raleigh' for
the 'raleigh' group might look like::
---
ntp_server: acme.example.org
database_server: storage.example.org
It is ok if these files do not exist, this is an optional feature.
Tip: In Ansible 1.2 or later the group_vars/ and host_vars/ directories can exist in either
the playbook directory OR the inventory directory. If both paths exist, variables in the playbook
directory will be loaded second.
Tip: Keeping your inventory file and variables in a git repo (or other version control)
is an excellent way to track changes to your inventory and host variables.
.. versionadded:: 0.5
If you ever have two python interpreters on a system, or your Python version 2 interpreter is not found
at /usr/bin/python, set an inventory variable called 'ansible_python_interpreter' to the Python
interpreter path you would like to use.
.. seealso::
:doc:`examples`
Examples of basic commands
:doc:`playbooks`
Learning ansible's configuration management language
`Mailing List <http://groups.google.com/group/ansible-project>`_
Questions? Help? Ideas? Stop by the list on Google Groups
`irc.freenode.net <http://irc.freenode.net>`_
#ansible IRC chat channel

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.. _patterns:
Inventory & Patterns
====================
Ansible works against multiple systems in your infrastructure at the
same time. It does this by selecting portions of systems listed in
Ansible's inventory file, which defaults to /etc/ansible/hosts.
.. contents::
:depth: 2
.. _inventoryformat:
Hosts and Groups
++++++++++++++++
The format for /etc/ansible/hosts is an INI format and looks like this::
mail.example.com
[webservers]
foo.example.com
bar.example.com
[dbservers]
one.example.com
two.example.com
three.example.com
The things in brackets are group names. You don't have to have them,
but they are useful.
If you have hosts that run on non-standard SSH ports you can put the port number
after the hostname with a colon. Ports listed in any SSH config file won't be read,
so it is important that you set them if things are not running on the default port::
badwolf.example.com:5309
Suppose you have just static IPs and want to set up some aliases that don't live in your host file, or you are connecting through tunnels. You can do things like this::
jumper ansible_ssh_port=5555 ansible_ssh_host=192.168.1.50
In the above example, trying to ansible against the host alias "jumper" (which may not even be a real hostname) will contact 192.168.1.50 on port 5555.
Adding a lot of hosts? In 0.6 and later, if you have a lot of hosts following similar patterns you can do this rather than listing each hostname::
[webservers]
www[01:50].example.com
In 1.0 and later, you can also do this for alphabetic ranges::
[databases]
db-[a:f].example.com
For numeric patterns, leading zeros can be included or removed, as desired. Ranges are inclusive.
In 1.1 and later, you can also select the connection type and user on a per host basis::
[targets]
localhost ansible_connection=local
other1.example.com ansible_connection=ssh ansible_ssh_user=mpdehaan
other2.example.com ansible_connection=ssh ansible_ssh_user=mdehaan
All of these variables can of course also be set outside of the inventory file, in 'host_vars' if you wish
to keep your inventory file simple.
List of Reserved Inventory Parameters
+++++++++++++++++++++++++++++++++++++
As a summary, you can set these parameters as host inventory variables. (Some we have already
mentioned).
ansible_ssh_host
The name of the host to connect to, if different from the alias you wish to give to it.
ansible_ssh_port
The ssh port number, if not 22
ansible_ssh_user
The default ssh user name to use.
ansible_ssh_pass
The ssh password to use (this is insecure, we strongly recommend using --ask-pass or SSH keys)
ansible_connection
Connection type of the host. Candidates are local, ssh or paramiko. The default is paramiko before Ansible 1.2, and 'smart' afterwards which detects whether usage of 'ssh' would be feasible based on whether ControlPersist is supported.
ansible_ssh_private_key_file
Private key file used by ssh. Useful if using multiple keys and you don't want to use SSH agent.
ansible_syslog_facility
The syslog facility to log to.
ansible_python_interpreter
The target host python path. This is userful for systems with more
than one Python or not located at "/usr/bin/python" such as \*BSD, or where /usr/bin/python
is not a 2.X series Python.
ansible\_\*\_interpreter
Works for anything such as ruby or perl and works just like ansible_python_interpreter.
This replaces shebang of modules which will run on that host.
Examples from a host file::
some_host ansible_ssh_port=2222 ansible_ssh_user=manager
aws_host ansible_ssh_private_key_file=/home/example/.ssh/aws.pem
freebsd_host ansible_python_interpreter=/usr/local/bin/python
ruby_module_host ansible_ruby_interpreter=/usr/bin/ruby.1.9.3
Selecting Targets
+++++++++++++++++
We'll go over how to use the command line in :doc:`examples` section, however, basically it looks like this::
ansible <pattern_goes_here> -m <module_name> -a <arguments>
Such as::
ansible webservers -m service -a "name=httpd state=restarted"
Within :doc:`playbooks`, these patterns can be used for even greater purposes.
Anyway, to use Ansible, you'll first need to know how to tell Ansible which hosts in your inventory file to talk to.
This is done by designating particular host names or groups of hosts.
The following patterns target all hosts in the inventory file::
all
*
Basically 'all' is an alias for '*'. It is also possible to address a specific host or hosts::
one.example.com
one.example.com:two.example.com
192.168.1.50
192.168.1.*
The following patterns address one or more groups, which are denoted
with the aforementioned bracket headers in the inventory file::
webservers
webservers:dbservers
You can exclude groups as well, for instance, all webservers not in Phoenix::
webservers:!phoenix
You can also specify the intersection of two groups::
webservers:&staging
You can do combinations::
webservers:dbservers:!phoenix:&staging
You can also use variables::
webservers:!{{excluded}}:&{{required}}
Individual host names, IPs and groups, can also be referenced using
wildcards::
*.example.com
*.com
It's also ok to mix wildcard patterns and groups at the same time::
one*.com:dbservers
And if the pattern starts with a '~' it is treated as a regular expression::
~(web|db).*\.example\.com
Easy enough. See :doc:`examples` and then :doc:`playbooks` for how to do things to selected hosts.
Host Variables
++++++++++++++
It is easy to assign variables to hosts that will be used later in playbooks::
[atlanta]
host1 http_port=80 maxRequestsPerChild=808
host2 http_port=303 maxRequestsPerChild=909
Group Variables
+++++++++++++++
Variables can also be applied to an entire group at once::
[atlanta]
host1
host2
[atlanta:vars]
ntp_server=ntp.atlanta.example.com
proxy=proxy.atlanta.example.com
Groups of Groups, and Group Variables
+++++++++++++++++++++++++++++++++++++
It is also possible to make groups of groups and assign
variables to groups. These variables can be used by /usr/bin/ansible-playbook, but not
/usr/bin/ansible::
[atlanta]
host1
host2
[raleigh]
host2
host3
[southeast:children]
atlanta
raleigh
[southeast:vars]
some_server=foo.southeast.example.com
halon_system_timeout=30
self_destruct_countdown=60
escape_pods=2
[usa:children]
southeast
northeast
southwest
southeast
If you need to store lists or hash data, or prefer to keep host and group specific variables
separate from the inventory file, see the next section.
Splitting Out Host and Group Specific Data
++++++++++++++++++++++++++++++++++++++++++
.. versionadded:: 0.6
In addition to the storing variables directly in the INI file, host
and group variables can be stored in individual files relative to the
inventory file. These variable files are in YAML format.
Assuming the inventory file path is::
/etc/ansible/hosts
If the host is named 'foosball', and in groups 'raleigh' and 'webservers', variables
in YAML files at the following locations will be made available to the host::
/etc/ansible/group_vars/raleigh
/etc/ansible/group_vars/webservers
/etc/ansible/host_vars/foosball
For instance, suppose you have hosts grouped by datacenter, and each datacenter
uses some different servers. The data in the groupfile '/etc/ansible/group_vars/raleigh' for
the 'raleigh' group might look like::
---
ntp_server: acme.example.org
database_server: storage.example.org
It is ok if these files do not exist, this is an optional feature.
Tip: In Ansible 1.2 or later the group_vars/ and host_vars/ directories can exist in either
the playbook directory OR the inventory directory. If both paths exist, variables in the playbook
directory will be loaded second.
Tip: Keeping your inventory file and variables in a git repo (or other version control)
is an excellent way to track changes to your inventory and host variables.
.. versionadded:: 0.5
If you ever have two python interpreters on a system, or your Python version 2 interpreter is not found
at /usr/bin/python, set an inventory variable called 'ansible_python_interpreter' to the Python
interpreter path you would like to use.
.. seealso::
:doc:`examples`
Examples of basic commands
:doc:`playbooks`
Learning ansible's configuration management language
`Mailing List <http://groups.google.com/group/ansible-project>`_
Questions? Help? Ideas? Stop by the list on Google Groups
`irc.freenode.net <http://irc.freenode.net>`_
#ansible IRC chat channel

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Playbooks
=========
.. contents::
:depth: 2
Introduction
````````````
Playbooks are a completely different way to use ansible than in task execution mode, and are
particularly powerful. Simply put, playbooks are the basis for a really simple
configuration management and multi-machine deployment system,
unlike any that already exist, and one that is very well suited to deploying complex applications.
Playbooks can declare configurations, but they can also orchestrate steps of
any manual ordered process, even as different steps must bounce back and forth
between sets of machines in particular orders. They can launch tasks
synchronously or asynchronously.
While you might run the main /usr/bin/ansible program for ad-hoc
tasks, playbooks are more likely to be kept in source control and used
to push out your configuration or assure the configurations of your
remote systems are in spec.
Let's dive in and see how they work. As you go, you may wish to open
the `github examples directory <https://github.com/ansible/ansible/tree/devel/examples/playbooks>`_ in
another tab, so you can apply the theory to what things look like in practice.
There are also some full sets of playbooks illustrating a lot of these techniques in the
`ansible-examples repository <https://github.com/ansible/ansible-examples>`_.
Playbook Language Example
`````````````````````````
Playbooks are expressed in YAML format and have a minimum of syntax.
Each playbook is composed of one or more 'plays' in a list.
The goal of a play is to map a group of hosts to some well defined roles, represented by
things ansible calls tasks. At a basic level, a task is nothing more than a call
to an ansible module, which you should have learned about in earlier chapters.
By composing a playbook of multiple 'plays', it is possible to
orchestrate multi-machine deployments, running certain steps on all
machines in the webservers group, then certain steps on the database
server group, then more commands back on the webservers group, etc.
For starters, here's a playbook that contains just one play::
---
- hosts: webservers
vars:
http_port: 80
max_clients: 200
remote_user: root
tasks:
- name: ensure apache is at the latest version
yum: pkg=httpd state=latest
- name: write the apache config file
template: src=/srv/httpd.j2 dest=/etc/httpd.conf
notify:
- restart apache
- name: ensure apache is running
service: name=httpd state=started
handlers:
- name: restart apache
service: name=httpd state=restarted
Below, we'll break down what the various features of the playbook language are.
Basics
``````
Hosts and Users
+++++++++++++++
For each play in a playbook, you get to choose which machines in your infrastructure
to target and what remote user to complete the steps (called tasks) as.
The `hosts` line is a list of one or more groups or host patterns,
separated by colons, as described in the :ref:`patterns`
documentation. The `remote_user` is just the name of the user account::
---
- hosts: webservers
remote_user: root
.. Note::
The `remote_user` parameter was formerly called just `user`. It was renamed in Ansible 1.4 to make it more distinguishable from the `user` module (used to create users on remote systems).
Support for running things from sudo is also available::
---
- hosts: webservers
remote_user: yourname
sudo: yes
You can also use sudo on a particular task instead of the whole play::
---
- hosts: webservers
remote_user: yourname
tasks:
- service: name=nginx state=started
sudo: yes
You can also login as you, and then sudo to different users than root::
---
- hosts: webservers
remote_user: yourname
sudo: yes
sudo_user: postgres
If you need to specify a password to sudo, run `ansible-playbook` with ``--ask-sudo-pass`` (`-K`).
If you run a sudo playbook and the playbook seems to hang, it's probably stuck at the sudo prompt.
Just `Control-C` to kill it and run it again with `-K`.
.. important::
When using `sudo_user` to a user other than root, the module
arguments are briefly written into a random tempfile in /tmp.
These are deleted immediately after the command is executed. This
only occurs when sudoing from a user like 'bob' to 'timmy', not
when going from 'bob' to 'root', or logging in directly as 'bob' or
'root'. If this concerns you that this data is briefly readable
(not writeable), avoid transferring uncrypted passwords with
`sudo_user` set. In other cases, '/tmp' is not used and this does
not come into play. Ansible also takes care to not log password
parameters.
Vars section
++++++++++++
The `vars` section contains a list of variables and values that can be used in the plays, like this::
---
- hosts: webservers
remote_user: root
vars:
http_port: 80
van_halen_port: 5150
other: 'magic'
.. note::
You can also keep variables in separate files and include them alongside inline `vars` with a `vars_files` declaration
in the play. See the `Advanced Playbooks chapter <http://www.ansibleworks.com/docs/playbooks2.html#variable-file-separation>`_
for more info.
These variables can be used later in the playbook like this::
{{ varname }}
Variables are passed through the Jinja2 templating engine. Any valid Jinja2
expression can be used between the curly braces, including the use of filters
to modify the variable (for example, `{{ varname|int }}` ensures the variable is
interpreted as an integer).
Jinja2 expressions are very similar to Python and even if you are not working
with Python you should feel comfortable with them. See the `Jinja2 documentation
<http://jinja.pocoo.org/docs/templates/>`_ to learn more about the syntax.
Please note that Jinja2 loops and conditionals are only useful in Ansible
templates, not in playbooks. Use the 'when' and 'with' keywords for
conditionals and loops in Ansible playbooks.
If there are discovered variables about the system, called 'facts', these variables bubble up back into the playbook, and can be used on each system just like explicitly set variables. Ansible provides several
of these, prefixed with 'ansible', which are documented under 'setup' in the module documentation. Additionally,
facts can be gathered by ohai and facter if they are installed. Facter variables are prefixed with ``facter_`` and Ohai variables are prefixed with ``ohai_``. These add extra dependencies and are only there for ease of users
porting over from those other configuration systems. Finally, it's possible to drop files
on to the remote systems that provide additional sources of fact data, see "Facts.d" as documented
in the Advanced Playbooks section.
How about an example. If I wanted to write the hostname into the /etc/motd file, I could say::
- name: write the motd
template: src=/srv/templates/motd.j2 dest=/etc/motd
And in /srv/templates/motd.j2::
You are logged into {{ facter_hostname }}
But we're getting ahead of ourselves, as that just showed a task in a playbook ahead of schedule. Let's talk about tasks.
Tasks list
++++++++++
Each play contains a list of tasks. Tasks are executed in order, one
at a time, against all machines matched by the host pattern,
before moving on to the next task. It is important to understand that, within a play,
all hosts are going to get the same task directives. It is the purpose of a play to map
a selection of hosts to tasks.
When running the playbook, which runs top to bottom, hosts with failed tasks are
taken out of the rotation for the entire playbook. If things fail, simply correct the playbook file and rerun.
The goal of each task is to execute a module, with very specific arguments.
Variables, as mentioned above, can be used in arguments to modules.
Modules are 'idempotent', meaning if you run them
again, they will make only the changes they must in order to bring the
system to the desired state. This makes it very safe to rerun
the same playbook multiple times. They won't change things
unless they have to change things.
The `command` and `shell` modules will typically rerun the same command again,
which is totally ok if the command is something like
'chmod' or 'setsebool', etc. Though there is a 'creates' flag available which can
be used to make these modules also idempotent.
Every task should have a `name`, which is included in the output from
running the playbook. This is output for humans, so it is
nice to have reasonably good descriptions of each task step. If the name
is not provided though, the string fed to 'action' will be used for
output.
Tasks can be declared using the legacy "action: module options" format, but
it is recommeded that you use the more conventional "module: options" format.
This recommended format is used throughout the documentation, but you may
encounter the older format in some playbooks.
Here is what a basic task looks like, as with most modules,
the service module takes key=value arguments::
tasks:
- name: make sure apache is running
service: name=httpd state=running
The `command` and `shell` modules are the one modules that just takes a list
of arguments, and don't use the key=value form. This makes
them work just like you would expect. Simple::
tasks:
- name: disable selinux
command: /sbin/setenforce 0
The command and shell module care about return codes, so if you have a command
whose successful exit code is not zero, you may wish to do this::
tasks:
- name: run this command and ignore the result
shell: /usr/bin/somecommand || /bin/true
Or this::
tasks:
- name: run this command and ignore the result
shell: /usr/bin/somecommand
ignore_errors: True
If the action line is getting too long for comfort you can break it on
a space and indent any continuation lines::
tasks:
- name: Copy ansible inventory file to client
copy: src=/etc/ansible/hosts dest=/etc/ansible/hosts
owner=root group=root mode=0644
Variables can be used in action lines. Suppose you defined
a variable called 'vhost' in the 'vars' section, you could do this::
tasks:
- name: create a virtual host file for {{ vhost }}
template: src=somefile.j2 dest=/etc/httpd/conf.d/{{ vhost }}
Those same variables are usable in templates, which we'll get to later.
Now in a very basic playbook all the tasks will be listed directly in that play, though it will usually
make more sense to break up tasks using the 'include:' directive. We'll show that a bit later.
Action Shorthand
````````````````
.. versionadded:: 0.8
Ansible prefers listing modules like this in 0.8 and later::
template: src=templates/foo.j2 dest=/etc/foo.conf
You will notice in earlier versions, this was only available as::
action: template src=templates/foo.j2 dest=/etc/foo.conf
The old form continues to work in newer versions without any plan of deprecation.
Running Operations On Change
````````````````````````````
As we've mentioned, modules are written to be 'idempotent' and can relay when
they have made a change on the remote system. Playbooks recognize this and
have a basic event system that can be used to respond to change.
These 'notify' actions are triggered at the end of each block of tasks in a playbook, and will only be
triggered once even if notified by multiple different tasks.
For instance, multiple resources may indicate
that apache needs to be restarted because they have changed a config file,
but apache will only be bounced once to avoid unneccessary restarts.
Here's an example of restarting two services when the contents of a file
change, but only if the file changes::
- name: template configuration file
template: src=template.j2 dest=/etc/foo.conf
notify:
- restart memcached
- restart apache
The things listed in the 'notify' section of a task are called
handlers.
Handlers are lists of tasks, not really any different from regular
tasks, that are referenced by name. Handlers are what notifiers
notify. If nothing notifies a handler, it will not run. Regardless
of how many things notify a handler, it will run only once, after all
of the tasks complete in a particular play.
Here's an example handlers section::
handlers:
- name: restart memcached
service: name=memcached state=restarted
- name: restart apache
service: name=apache state=restarted
Handlers are best used to restart services and trigger reboots. You probably
won't need them for much else.
.. note::
Notify handlers are always run in the order written.
Roles are described later on. It's worthwhile to point out that handlers are
automatically processed between 'pre_tasks', 'roles', 'tasks', and 'post_tasks'
sections. If you ever want to flush all the handler commands immediately though,
in 1.2 and later, you can::
tasks:
- shell: some tasks go here
- meta: flush_handlers
- shell: some other tasks
In the above example any queued up handlers would be processed early when the 'meta'
statement was reached. This is a bit of a niche case but can come in handy from
time to time.
Task Include Files And Encouraging Reuse
````````````````````````````````````````
Suppose you want to reuse lists of tasks between plays or playbooks. You can use
include files to do this. Use of included task lists is a great way to define a role
that system is going to fulfill. Remember, the goal of a play in a playbook is to map
a group of systems into multiple roles. Let's see what this looks like...
A task include file simply contains a flat list of tasks, like so::
---
# possibly saved as tasks/foo.yml
- name: placeholder foo
command: /bin/foo
- name: placeholder bar
command: /bin/bar
Include directives look like this, and can be mixed in with regular tasks in a playbook::
tasks:
- include: tasks/foo.yml
You can also pass variables into includes. We call this a 'parameterized include'.
For instance, if deploying multiple wordpress instances, I could
contain all of my wordpress tasks in a single wordpress.yml file, and use it like so::
tasks:
- include: wordpress.yml user=timmy
- include: wordpress.yml user=alice
- include: wordpress.yml user=bob
Variables passed in can then be used in the included files. You can reference them like this::
{{ user }}
(In addition to the explicitly passed-in parameters, all variables from
the vars section are also available for use here as well.)
Starting in 1.0, variables can also be passed to include files using an alternative syntax,
which also supports structured variables::
tasks:
- include: wordpress.yml
vars:
remote_user: timmy
some_list_variable:
- alpha
- beta
- gamma
Playbooks can include other playbooks too, but that's mentioned in a later section.
.. note::
As of 1.0, task include statements can be used at arbitrary depth.
They were previously limited to a single level, so task includes
could not include other files containing task includes.
Includes can also be used in the 'handlers' section, for instance, if you
want to define how to restart apache, you only have to do that once for all
of your playbooks. You might make a handlers.yml that looks like::
---
# this might be in a file like handlers/handlers.yml
- name: restart apache
service: name=apache state=restarted
And in your main playbook file, just include it like so, at the bottom
of a play::
handlers:
- include: handlers/handlers.yml
You can mix in includes along with your regular non-included tasks and handlers.
Includes can also be used to import one playbook file into another. This allows
you to define a top-level playbook that is composed of other playbooks.
For example::
- name: this is a play at the top level of a file
hosts: all
remote_user: root
tasks:
- name: say hi
tags: foo
shell: echo "hi..."
- include: load_balancers.yml
- include: webservers.yml
- include: dbservers.yml
Note that you cannot do variable substitution when including one playbook
inside another.
.. note::
You can not conditionally path the location to an include file,
like you can with 'vars_files'. If you find yourself needing to do
this, consider how you can restructure your playbook to be more
class/role oriented. This is to say you cannot use a 'fact' to
decide what include file to use. All hosts contained within the
play are going to get the same tasks. ('*when*' provides some
ability for hosts to conditionally skip tasks).
.. _roles:
Roles
`````
.. versionadded:: 1.2
Now that you have learned about vars_files, tasks, and handlers, what is the best way to organize your playbooks?
The short answer is to use roles! Roles are ways of automatically loading certain vars_files, tasks, and
handlers based on a known file structure. Grouping content by roles also allows easy sharing of roles with other users.
Roles are just automation around 'include' directives as redescribed above, and really don't contain much
additional magic beyond some improvements to search path handling for referenced files. However, that can be a big thing!
Example project structure::
site.yml
webservers.yml
fooservers.yml
roles/
common/
files/
templates/
tasks/
handlers/
vars/
meta/
webservers/
files/
templates/
tasks/
handlers/
vars/
meta/
In a playbook, it would look like this::
---
- hosts: webservers
roles:
- common
- webservers
This designates the following behaviors, for each role 'x':
- If roles/x/tasks/main.yml exists, tasks listed therein will be added to the play
- If roles/x/handlers/main.yml exists, handlers listed therein will be added to the play
- If roles/x/vars/main.yml exists, variables listed therein will be added to the play
- If roles/x/meta/main.yml exists, any role dependencies listed therein will be added to the list of roles (1.3 and later)
- Any copy tasks can reference files in roles/x/files/ without having to path them relatively or absolutely
- Any script tasks can reference scripts in roles/x/files/ without having to path them relatively or absolutely
- Any template tasks can reference files in roles/x/templates/ without having to path them relatively or absolutely
.. note::
Role dependencies are discussed below.
If any files are not present, they are just ignored. So it's ok to not have a 'vars/' subdirectory for the role,
for instance.
Note, you are still allowed to list tasks, vars_files, and handlers "loose" in playbooks without using roles,
but roles are a good organizational feature and are highly recommended. if there are loose things in the playbook,
the roles are evaluated first.
Also, should you wish to parameterize roles, by adding variables, you can do so, like this::
---
- hosts: webservers
roles:
- common
- { role: foo_app_instance, dir: '/opt/a', port: 5000 }
- { role: foo_app_instance, dir: '/opt/b', port: 5001 }
While it's probably not something you should do often, you can also conditionally apply roles like so::
---
- hosts: webservers
roles:
- { role: some_role, when: "ansible_os_family == 'RedHat'" }
This works by applying the conditional to every task in the role. Conditionals are covered later on in
the documentation.
Finally, you may wish to assign tags to the roles you specify. You can do so inline:::
---
- hosts: webservers
roles:
- { role: foo, tags: ["bar", "baz"] }
If the play still has a 'tasks' section, those tasks are executed after roles are applied.
If you want to define certain tasks to happen before AND after roles are applied, you can do this::
---
- hosts: webservers
pre_tasks:
- shell: echo 'hello'
roles:
- { role: some_role }
tasks:
- shell: echo 'still busy'
post_tasks:
- shell: echo 'goodbye'
.. note::
If using tags with tasks (described later as a means of only running part of a playbook),
be sure to also tag your pre_tasks and post_tasks and pass those along as well, especially if the pre
and post tasks are used for monitoring outage window control or load balancing.
Role Default Variables
``````````````````````
.. versionadded:: 1.3
Role default variables allow you to set default variables for included or dependent roles (see below). To create
defaults, simply add a `defaults/main.yml` file in your role directory. These variables will have the lowest priority
of any variables available, and can be easily overridden by any other variable, including inventory variables.
Role Dependencies
`````````````````
.. versionadded:: 1.3
Role dependencies allow you to automatically pull in other roles when using a role. Role dependencies are stored in the
`meta/main.yml` file contained within the role directory. This file should contain
a list of roles and parameters to insert before the specified role, such as the following in an example
`roles/myapp/meta/main.yml`::
---
dependencies:
- { role: common, some_parameter: 3 }
- { role: apache, port: 80 }
- { role: postgres, dbname: blarg, other_parameter: 12 }
Role dependencies can also be specified as a full path, just like top level roles::
---
dependencies:
- { role: '/path/to/common/roles/foo', x: 1 }
Roles dependencies are always executed before the role that includes them, and are recursive. By default,
roles can also only be added as a dependency once - if another role also lists it as a dependency it will
not be run again. This behavior can be overridden by adding `allow_duplicates: yes` to the `meta/main.yml` file.
For example, a role named 'car' could add a role named 'wheel' to its dependencies as follows::
---
dependencies:
- { role: wheel, n: 1 }
- { role: wheel, n: 2 }
- { role: wheel, n: 3 }
- { role: wheel, n: 4 }
And the `meta/main.yml` for wheel contained the following::
---
allow_duplicates: yes
dependencies:
- { role: tire }
- { role: brake }
The resulting order of execution would be as follows::
tire(n=1)
brake(n=1)
wheel(n=1)
tire(n=2)
brake(n=2)
wheel(n=2)
...
car
.. note::
Variable inheritance and scope are detailed in the Advanced Playbook section.
Executing A Playbook
````````````````````
Now that you've learned playbook syntax, how do you run a playbook? It's simple.
Let's run a playbook using a parallelism level of 10::
ansible-playbook playbook.yml -f 10
Tips and Tricks
```````````````
Look at the bottom of the playbook execution for a summary of the nodes that were targeted
and how they performed. General failures and fatal "unreachable" communication attempts are
kept separate in the counts.
If you ever want to see detailed output from successful modules as well as unsuccessful ones,
use the '--verbose' flag. This is available in Ansible 0.5 and later.
Also, in version 0.5 and later, Ansible playbook output is vastly upgraded if the cowsay
package is installed. Try it!
In version 0.7 and later, to see what hosts would be affected by a playbook before you run it, you
can do this::
ansible-playbook playbook.yml --list-hosts.
.. seealso::
:doc:`YAMLSyntax`
Learn about YAML syntax
:doc:`playbooks`
Review the basic Playbook language features
:doc:`playbooks2`
Learn about Advanced Playbook Features
:doc:`bestpractices`
Various tips about managing playbooks in the real world
:doc:`modules`
Learn about available modules
:doc:`moduledev`
Learn how to extend Ansible by writing your own modules
:doc:`patterns`
Learn about how to select hosts
`Github examples directory <https://github.com/ansible/ansible/tree/devel/examples/playbooks>`_
Complete playbook files from the github project source
`Mailing List <http://groups.google.com/group/ansible-project>`_
Questions? Help? Ideas? Stop by the list on Google Groups

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