.. _module_defaults:

Module defaults
===============

If you frequently call the same module with the same arguments, it can be useful to define default arguments for that particular module using the ``module_defaults`` keyword.

Here is a basic example:

.. code-block:: YAML

    - hosts: localhost
      module_defaults:
        ansible.builtin.file:
          owner: root
          group: root
          mode: 0755
      tasks:
        - name: Create file1
          ansible.builtin.file:
            state: touch
            path: /tmp/file1

        - name: Create file2
          ansible.builtin.file:
            state: touch
            path: /tmp/file2

        - name: Create file3
          ansible.builtin.file:
            state: touch
            path: /tmp/file3

The ``module_defaults`` keyword can be used at the play, block, and task level. Any module arguments explicitly specified in a task will override any established default for that module argument.

.. code-block:: YAML

    - block:
        - name: Print a message
          ansible.builtin.debug:
            msg: "Different message"
      module_defaults:
        ansible.builtin.debug:
          msg: "Default message"

You can remove any previously established defaults for a module by specifying an empty dict.

.. code-block:: YAML

    - name: Create file1
      ansible.builtin.file:
        state: touch
        path: /tmp/file1
      module_defaults:
        file: {}

.. note::
    Any module defaults set at the play level (and block/task level when using ``include_role`` or ``import_role``) will apply to any roles used, which may cause unexpected behavior in the role.

Here are some more realistic use cases for this feature.

Interacting with an API that requires auth.

.. code-block:: YAML

    - hosts: localhost
      module_defaults:
        ansible.builtin.uri:
          force_basic_auth: true
          user: some_user
          password: some_password
      tasks:
        - name: Interact with a web service
          ansible.builtin.uri:
            url: http://some.api.host/v1/whatever1

        - name: Interact with a web service
          ansible.builtin.uri:
            url: http://some.api.host/v1/whatever2

        - name: Interact with a web service
          ansible.builtin.uri:
            url: http://some.api.host/v1/whatever3

Setting a default AWS region for specific EC2-related modules.

.. code-block:: YAML

    - hosts: localhost
      vars:
        my_region: us-west-2
      module_defaults:
        amazon.aws.ec2:
          region: '{{ my_region }}'
        community.aws.ec2_instance_info:
          region: '{{ my_region }}'
        amazon.aws.ec2_vpc_net_info:
          region: '{{ my_region }}'

.. _module_defaults_groups:

Module defaults groups
----------------------

.. versionadded:: 2.7

Ansible 2.7 adds a preview-status feature to group together modules that share common sets of parameters. This makes it easier to author playbooks making heavy use of API-based modules such as cloud modules.

+---------+---------------------------+-----------------+
| Group   | Purpose                   | Ansible Version |
+=========+===========================+=================+
| aws     | Amazon Web Services       | 2.7             |
+---------+---------------------------+-----------------+
| azure   | Azure                     | 2.7             |
+---------+---------------------------+-----------------+
| gcp     | Google Cloud Platform     | 2.7             |
+---------+---------------------------+-----------------+
| k8s     | Kubernetes                | 2.8             |
+---------+---------------------------+-----------------+
| os      | OpenStack                 | 2.8             |
+---------+---------------------------+-----------------+
| acme    | ACME                      | 2.10            |
+---------+---------------------------+-----------------+
| docker* | Docker                    | 2.10            |
+---------+---------------------------+-----------------+
| ovirt   | oVirt                     | 2.10            |
+---------+---------------------------+-----------------+
| vmware  | VMware                    | 2.10            |
+---------+---------------------------+-----------------+

* The `docker_stack <docker_stack_module>`_ module is not included in the ``docker`` defaults group.

Use the groups with ``module_defaults`` by prefixing the group name with ``group/`` - for example ``group/aws``.

In a playbook, you can set module defaults for whole groups of modules, such as setting a common AWS region.

.. code-block:: YAML

    # example_play.yml
    - hosts: localhost
      module_defaults:
        group/aws:
          region: us-west-2
      tasks:
      - name: Get info
        aws_s3_bucket_info:

      # now the region is shared between both info modules

      - name: Get info
        ec2_ami_info:
          filters:
            name: 'RHEL*7.5*'

In ansible-core 2.12, collections can define their own groups in the ``meta/runtime.yml`` file. ``module_defaults`` does not take the ``collections`` keyword into account, so the fully qualified group name must be used for new groups in ``module_defaults``.

Here is an example ``runtime.yml`` file for a collection and a sample playbook using the group.

.. code-block:: YAML

   # collections/ansible_collections/ns/coll/meta/runtime.yml
   action_groups:
     groupname:
       - module
       - another.collection.module

.. code-block:: YAML

   - hosts: localhost
     module_defaults:
       group/ns.coll.groupname:
         option_name: option_value
     tasks:
       - ns.coll.module:
       - another.collection.module
