<commit_before>.. _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
   :backlinks: top

.. _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.  Default is paramiko
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::
<commit_msg>Fix RST formatting in documentation (underline too short)<commit_after>.. _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
   :backlinks: top

.. _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.  Default is paramiko
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::

{'fraction_non_alphanumeric': 0.06828571428571428, 'fraction_numerical': 0.013142857142857144, 'mean_word_length': 3.70497311827957, 'pattern_counts': {'":': 0, '<': 3, '<?xml version=': 0, '>': 3, 'https://': 0, 'lorem ipsum': 0, 'www.': 2, 'xml': 0}, 'pii_count': 4, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
{'dir': 'git-commits-cleaned', 'id': '6177833', 'n_tokens_mistral': 2140, 'n_tokens_neox': 1958, 'n_words': 971}