118 lines
3.7 KiB
Text
118 lines
3.7 KiB
Text
Playbooks
|
|
=========
|
|
|
|
.. seealso::
|
|
|
|
:doc:`YAMLScripts`
|
|
Learn about YAML syntax
|
|
:doc:`modules`
|
|
Learn about available modules and writing your own
|
|
:doc:`patterns`
|
|
Learn about how to select hosts
|
|
|
|
|
|
Playbooks are a completely different way to use ansible and are particularly awesome.
|
|
|
|
They are the basis for a really simple configuration management and deployment system, unlike any that already exist, and one that is very well suited to deploying complex multi-machine applications. While you might run the main 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.
|
|
|
|
|
|
Playbook Example
|
|
````````````````
|
|
|
|
Playbooks are expressed in YAML format and have a minimum of syntax. Each playbook is composed
|
|
of one or more patterns in a list. By composing a playbook of multiple patterns, 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::
|
|
|
|
---
|
|
- hosts: all
|
|
vars:
|
|
http_port: 80
|
|
max_clients: 200
|
|
user: root
|
|
tasks:
|
|
- include: base.yml somevar=3 othervar=4
|
|
- name: write the apache config file
|
|
action: template src=/srv/httpd.j2 dest=/etc/httpd.conf
|
|
notify:
|
|
- restart apache
|
|
- name: ensure apache is running
|
|
action: service name=httpd state=started
|
|
handlers:
|
|
- include: handlers.yml
|
|
|
|
Hosts line
|
|
``````````
|
|
|
|
The hosts line is alist of one or more groups or host patterns, seperated by colons.
|
|
|
|
webservers:dbservers:*.foo.example.com
|
|
|
|
Vars section
|
|
````````````
|
|
|
|
A list of variables that can be used in the 'action' lines of the template, or in
|
|
included templates. Variables are deferenced like this::
|
|
|
|
{{ varname }}
|
|
|
|
These variables will be pushed down to the managed systems for use in templating operations.
|
|
|
|
Further, if there are discovered variables about the system (say, if facter or ohai were
|
|
installed) these variables bubble up back into the playbook, and can be used on each
|
|
system just like explicitly set variables. Facter variables are prefixed with 'facter'
|
|
and Ohai variables are prefixed with 'ohai'.
|
|
|
|
Tasks list
|
|
``````````
|
|
|
|
Tasks are executed in order, one at a time, against all machines matched by the host
|
|
pattern, before moving on to the next task. Failed tasks are taken out of the rotation.
|
|
|
|
Task name and comment
|
|
`````````
|
|
|
|
Each task has a name (required) and optional comment. This is for informational purposes only
|
|
|
|
Task action
|
|
```````````
|
|
|
|
The action line is the name of an ansible module followed by parameters. Usually these
|
|
are expressed in key=value form, except for the command module, which looks just like a Linux/Unix
|
|
command line. See the module documentation for more info.
|
|
|
|
Notify statements
|
|
`````````````````
|
|
|
|
Nearly all modules are written to be 'idempotent' and can signal when they have affected a change
|
|
on the remote system. If a notify statement is used, the named handler will be run against
|
|
each system where a change was effected, but NOT on systems where no change occurred.
|
|
|
|
Handlers
|
|
````````
|
|
|
|
Handlers are lists of tasks, not really any different from regular tasks, that are referenced
|
|
by name.
|
|
|
|
Includes
|
|
````````
|
|
|
|
Not all tasks have to be listed directly in the main file. An include file can contain
|
|
a list of tasks (in YAML) as well, optionally passing extra variables into the file.
|
|
Variables passed in can be deferenced like this:
|
|
|
|
{{ variable }}
|
|
|
|
Asynchronous Actions and Polling
|
|
````````````````````````````````
|
|
|
|
(Information on this feature is pending)
|
|
|
|
Executing A Playbook
|
|
````````````````````
|
|
|
|
To run a playbook::
|
|
|
|
ansible-playbook playbook.yml
|
|
|