The -f 10 specifies the usage of 10 simultaneous processes.
Note that other than the command module, ansible modules do not work like simple scripts. They make
the remote system look like you state, and run the commands neccessary to get it there.
Example: Time-limited Background Operations
===========================================
Long running operations can be backgrounded, and their status can be checked on later. The same
job ID is given to the same task on all hosts, so you won't lose track. Polling support
is pending in the command line.
> ansible all -B 3600 -a "/usr/bin/long_running_operation --do-stuff"
> ansible all -n job_status -a jid=123456789
Any module other than 'copy' or 'template' can be backgrounded.
Example: File Transfer and Templating
=====================================
Ansible can SCP lots of files to multiple machines in parallel, and optionally use
them as template sources.
To just transfer a file directly to many different servers:
> ansible atlanta copy -a "/etc/hosts /tmp/hosts"
To use templating, first run the setup module to put the template variables you would
like to use on the remote host. Then use the template module to write the
files using the templates. Templates are written in Jinja2 format. Playbooks
(covered below) will run the setup module for you, making this even simpler.
> ansible webservers -m setup -a "favcolor=red ntp_server=192.168.1.1"
> ansible webservers -m template -a "src=/srv/motd.j2 dest=/etc/motd"
> ansible webservers -m template -a "src=/srv/ntp.j2 dest=/etc/ntp.conf"
Need something like the fqdn in a template? If facter or ohai are installed, data from these projects
will also be made available to the template engine, using 'facter_' and 'ohai_' prefixes for each.
Example: Software Deployment From Source Control
================================================
Deploy your webapp straight from git
> ansible webservers -m git -a "repo=git://foo dest=/srv/myapp version=HEAD"
Since ansible modules can notify change handlers (see 'Playbooks') it is possible
to tell ansible to run specific tasks when the code is updated, such as deploying
Perl/Python/PHP/Ruby directly from git and then restarting apache.
Other Modules
=============
Ansible has lots of other modules and they are growing.
See the library directory in the source checkout or the manpage:
[ansible-modules(5)](https://github.com/mpdehaan/ansible/blob/master/docs/man/man5/ansible-modules.5.asciidoc) that covers what's there and all the options they take.
Playbooks
=========
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.
* Everything is expressed in a simple YAML data format, not a custom language, not code.
* Playooks can have many steps
* Any step can run as any user
* Conditional handlers fire on 'notify'. Ex: restart apache only once, at the end, only if needed
* Tasks and handlers can be 'included' to faciliate sharing and reuse
* Include statements can take parameters for customization, and be used more than once per file
* Variables from the host system (from facter, ohai, etc) bubble-up for use in templates
* Variables can be deferenced like {{ varname }} in both include directives & templates
* Templates are powered by Jinja2: http://jinja.pocoo.org/docs/templates/#synopsis
To run a playbook:
ansible-playbook playbook.yml
See the playbook format manpage -- [ansible-playbook(5)](https://github.com/mpdehaan/ansible/blob/master/docs/man/man5/ansible-playbook.5.asciidoc) for more details.
API
===
The Python API is very powerful, and is how the ansible CLI and ansible-playbook
are implemented.
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' manpage.
{
"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.
