Lookup plugins are an Ansible-specific extension to the Jinja2 templating language. You can use lookup plugins to access data from outside sources (files, databases, key/value stores, APIs, and other services) within your playbooks. Like all :ref:`templating <playbooks_templating>`, lookups execute and are evaluated on the Ansible control machine. Ansible makes the data returned by a lookup plugin available using the standard templating system. You can use lookup plugins to load variables or templates with information from external sources. You can :ref:`create custom lookup plugins <developing_lookup_plugins>`.
- By default, lookup return values are marked as unsafe for security reasons. If you trust the outside source your lookup accesses, pass ``allow_unsafe=True`` to allow Jinja2 templates to evaluate lookup values.
Ansible enables all lookup plugins it can find. You can activate a custom lookup by either dropping it into a ``lookup_plugins`` directory adjacent to your play, inside the ``plugins/lookup/`` directory of a collection you have installed, inside a standalone role, or in one of the lookup directory sources configured in :ref:`ansible.cfg <ansible_configuration_settings>`.
You can use lookup plugins anywhere you can use templating in Ansible: in a play, in variables file, or in a Jinja2 template for the :ref:`template <template_module>` module. For more information on using lookup plugins, see :ref:`playbooks_lookups`.
Lookups are an integral part of loops. Wherever you see ``with_``, the part after the underscore is the name of a lookup. For this reason, most lookups output lists and take lists as input; for example, ``with_items`` uses the :ref:`items <items_lookup>` lookup::
You can combine lookups with :ref:`filters <playbooks_filters>`, :ref:`tests <playbooks_tests>` and even each other to do some complex data generation and manipulation. For example::
You can control how errors behave in all lookup plugins by setting ``errors`` to ``ignore``, ``warn``, or ``strict``. The default setting is ``strict``, which causes the task to fail if the lookup returns an error. For example:
[WARNING]: An unhandled exception occurred while running the lookup plugin 'file'. Error was a <class 'ansible.errors.AnsibleError'>, original message: could not locate file in lookup: /nosuchfile
fatal: [localhost]: FAILED! => {"msg": "An unhandled exception occurred while running the lookup plugin 'file'. Error was a <class 'ansible.errors.AnsibleError'>, original message: could not locate file in lookup: /nosuchfile"}
In Ansible 2.5, a new Jinja2 function called ``query`` was added for invoking lookup plugins. The difference between ``lookup`` and ``query`` is largely that ``query`` will always return a list.
The default behavior of ``lookup`` is to return a string of comma separated values. ``lookup`` can be explicitly configured to return a list using ``wantlist=True``.
This feature provides an easier and more consistent interface for interacting with the new ``loop`` keyword, while maintaining backwards compatibility with other uses of ``lookup``.
You can use ``ansible-doc -t lookup -l`` to see the list of available plugins. Use ``ansible-doc -t lookup <plugin name>`` to see specific documents and examples.
