Lookup plugins allow Ansible to access data from outside sources. This can include reading the filesystem in addition to contacting external datastores and services. Like all templating, these plugins are evaluated on the Ansible control machine, not on the target/remote.
The data returned by a lookup plugin is made available using the standard templating system in Ansible, and are typically used to load variables or templates with information from those systems.
Lookups are an Ansible-specific extension to the Jinja2 templating language.
Note
Warning
|quote
filter to ensure safe usage.You can activate a custom lookup by either dropping it into a lookup_plugins
directory adjacent to your play, inside a role, or by putting it in one of the lookup directory sources configured in ansible.cfg.
Lookup plugins can be used anywhere you can use templating in Ansible: in a play, in variables file, or in a Jinja2 template for the template module.
vars: file_contents: "{{lookup('file', 'path/to/file.txt')}}"
Lookups are an integral part of loops. Wherever you see with_
, the part after the underscore is the name of a lookup. This is also the reason most lookups output lists and take lists as input; for example, with_items
uses the items lookup:
tasks: - name: count to 3 debug: msg={{item}} with_items: [1, 2, 3]
You can combine lookups with Filters, Tests and even each other to do some complex data generation and manipulation. For example:
tasks: - name: valid but useless and over complicated chained lookups and filters debug: msg="find the answer here:\n{{ lookup('url', 'https://google.com/search/?q=' + item|urlencode)|join(' ') }}" with_nested: - "{{lookup('consul_kv', 'bcs/' + lookup('file', '/the/question') + ', host=localhost, port=2000')|shuffle}}" - "{{lookup('sequence', 'end=42 start=2 step=2')|map('log', 4)|list)}}" - ['a', 'c', 'd', 'c']
New in version 2.6.
You can now 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. For example:
To ignore errors:
- name: file doesnt exist, but i dont care .. file plugin itself warns anyways ... debug: msg="{{ lookup('file', '/idontexist', errors='ignore') }}"
[WARNING]: Unable to find '/idontexist' in expected paths (use -vvvvv to see paths) ok: [localhost] => { "msg": "" }
To get a warning instead of a failure:
- name: file doesnt exist, let me know, but continue debug: msg="{{ lookup('file', '/idontexist', errors='warn') }}"
[WARNING]: Unable to find '/idontexist' in expected paths (use -vvvvv to see paths) [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: /idontexist ok: [localhost] => { "msg": "" }
Fatal error (the default):
- name: file doesnt exist, FAIL (this is the default) debug: msg="{{ lookup('file', '/idontexist', errors='strict') }}"
[WARNING]: Unable to find '/idontexist' in expected paths (use -vvvvv to see paths) 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: /idontexist"}
query
New in version 2.5.
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 was done primarily to provide an easier and more consistent interface for interacting with the new loop
keyword, while maintaining backwards compatibility with other uses of lookup
.
The following examples are equivalent:
lookup('dict', dict_variable, wantlist=True) query('dict', dict_variable)
As demonstrated above the behavior of wantlist=True
is implicit when using query
.
Additionally, q
was introduced as a shortform of query
:
q('dict', dict_variable)
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.
Avi
objectsSee also
© 2012–2018 Michael DeHaan
© 2018–2019 Red Hat, Inc.
Licensed under the GNU General Public License version 3.
https://docs.ansible.com/ansible/2.9/plugins/lookup.html