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::
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::
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.
