Vars Plugins

• Enabling vars plugins
• Using vars plugins
• Plugin Lists

Vars plugins inject additional variable data into Ansible runs that did not come from an inventory source, playbook, or command line. Playbook constructs like ‘host_vars’ and ‘group_vars’ work using vars plugins.

Vars plugins were partially implemented in Ansible 2.0 and rewritten to be fully implemented starting with Ansible 2.4.

The host_group_vars plugin shipped with Ansible enables reading variables from Assigning a variable to one machine: host variables and Assigning a variable to many machines: group variables.

Enabling vars plugins

You can activate a custom vars plugin by either dropping it into a vars_plugins directory adjacent to your play, inside a role, or by putting it in one of the directory sources configured in ansible.cfg.

Starting in Ansible 2.10, vars plugins can require whitelisting rather than running by default. To enable a plugin that requires whitelisting set vars_plugins_enabled in the defaults section of ansible.cfg or set the ANSIBLE_VARS_ENABLED environment variable to the list of vars plugins you want to execute. By default, the host_group_vars plugin shipped with Ansible is whitelisted.

Starting in Ansible 2.10, you can use vars plugins in collections. All vars plugins in collections require whitelisting and need to use the fully qualified collection name in the format namespace.collection_name.vars_plugin_name.

[defaults]
vars_plugins_enabled = host_group_vars,namespace.collection_name.vars_plugin_name

Using vars plugins

By default, vars plugins are used on demand automatically after they are enabled.

Starting in Ansible 2.10, vars plugins can be made to run at specific times. ansible-inventory does not use these settings, and always loads vars plugins.

The global setting RUN_VARS_PLUGINS can be set in ansible.cfg using run_vars_plugins in the defaults section or by the ANSIBLE_RUN_VARS_PLUGINS environment variable. The default option, demand, runs any enabled vars plugins relative to inventory sources whenever variables are demanded by tasks. You can use the option start to run any enabled vars plugins relative to inventory sources after importing that inventory source instead.

You can also control vars plugin execution on a per-plugin basis for vars plugins that support the stage option. To run the host_group_vars plugin after importing inventory you can add the following to ansible.cfg:

[vars_host_group_vars]
stage = inventory

Plugin Lists

You can use ansible-doc -t vars -l to see the list of available plugins. Use ansible-doc -t vars <plugin name> to see specific plugin-specific documentation and examples.