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1cec3c8daf
* Add docs detailing how to convert many with_X style loops to use loop and filters. Fixes #40727 * Switch lookup used in query vs lookup comparison, to not recommend use of nested lookup * Improve docs based on feedback
193 lines
4.5 KiB
Text
193 lines
4.5 KiB
Text
With the release of Ansible 2.5, the recommended way to perform loops is the use the new ``loop`` keyword instead of ``with_X`` style loops.
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In many cases, ``loop`` syntax is better expressed using filters instead of more complex use of ``query`` or ``lookup``.
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The following examples will show how to convert many common ``with_`` style loops to ``loop`` and filters.
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with_list
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---------
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``with_list`` is directly replaced by ``loop``.
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.. code-block:: yaml+jinja
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- name: with_list
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debug:
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msg: "{{ item }}"
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with_list:
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- one
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- two
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- name: with_list -> loop
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debug:
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msg: "{{ item }}"
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loop:
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- one
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- two
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with_items
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----------
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``with_items`` is replaced by ``loop`` and the ``flatten`` filter.
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.. code-block:: yaml+jinja
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- name: with_items
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debug:
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msg: "{{ item }}"
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with_items: "{{ items }}"
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- name: with_items -> loop
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debug:
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msg: "{{ item }}"
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loop: "{{ items|flatten(levels=1) }}"
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with_indexed_items
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------------------
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``with_indexed_items`` is replaced by ``loop``, the ``flatten`` filter and ``loop_control.index_var``.
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.. code-block:: yaml+jinja
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- name: with_indexed_items
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debug:
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msg: "{{ item.0 }} - {{ item.1 }}"
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with_indexed_items: "{{ items }}"
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- name: with_indexed_items -> loop
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debug:
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msg: "{{ index }} - {{ item }}"
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loop: "{{ items|flatten(levels=1) }}"
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loop_control:
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index_var: index
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with_flattened
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--------------
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``with_flattened`` is replaced by ``loop`` and the ``flatten`` filter.
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.. code-block:: yaml+jinja
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- name: with_flattened
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debug:
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msg: "{{ item }}"
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with_flattened: "{{ items }}"
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- name: with_flattened -> loop
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debug:
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msg: "{{ item }}"
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loop: "{{ items|flatten }}"
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with_together
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-------------
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``with_together`` is replaced by ``loop`` and the ``zip`` filter.
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.. code-block:: yaml+jinja
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- name: with_together
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debug:
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msg: "{{ item.0 }} - {{ item.1 }}"
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with_together:
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- "{{ list_one }}"
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- "{{ list_two }}"
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- name: with_together -> loop
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debug:
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msg: "{{ item.0 }} - {{ item.1 }}"
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loop: "{{ list_one|zip(list_two)|list }}"
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with_dict
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---------
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``with_dict`` can be substituted by ``loop`` and either the ``dictsort`` or ``dict2items`` filters.
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.. code-block:: yaml+jinja
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- name: with_dict
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debug:
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msg: "{{ item.key }} - {{ item.value }}"
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with_dict: "{{ dictionary }}"
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- name: with_dict -> loop (option 1)
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debug:
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msg: "{{ item.key }} - {{ item.value }}"
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loop: "{{ dictionary|dict2items }}"
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- name: with_dict -> loop (option 2)
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debug:
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msg: "{{ item.0 }} - {{ item.1 }}"
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loop: "{{ dictionary|dictsort }}"
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with_sequence
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-------------
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``with_sequence`` is replaced by ``loop`` and the ``range`` function, and potentially the ``format`` filter.
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.. code-block:: yaml+jinja
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- name: with_sequence
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debug:
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msg: "{{ item }}"
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with_sequence: start=0 end=4 stride=2 format=testuser%02x
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- name: with_sequence -> loop
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debug:
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msg: "{{ 'testuser%02x' | format(item) }}"
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# range is exclusive of the end point
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loop: "{{ range(0, 4 + 1, 2)|list }}"
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with_subelements
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----------------
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``with_subelements`` is replaced by ``loop`` and the ``subelements`` filter.
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.. code-block:: yaml+jinja
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- name: with_subelements
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debug:
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msg: "{{ item.0.name }} - {{ item.1 }}"
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with_subelements:
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- "{{ users }}"
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- mysql.hosts
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- name: with_subelements -> loop
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debug:
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msg: "{{ item.0.name }} - {{ item.1 }}"
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loop: "{{ users|subelements('mysql.hosts') }}"
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with_nested/with_cartesian
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--------------------------
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``with_nested`` and ``with_cartesian`` are replaced by loop and the ``product`` filter.
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.. code-block:: yaml+jinja
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- name: with_nested
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debug:
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msg: "{{ item.0 }} - {{ item.1 }}"
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with_nested:
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- "{{ list_one }}"
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- "{{ list_two }}"
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- name: with_nested -> loop
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debug:
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msg: "{{ item.0 }} - {{ item.1 }}"
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loop: "{{ list_one|product(list_two)|list }}"
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with_random_choice
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------------------
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``with_random_choice`` is replaced by just use of the ``random`` filter, without need of ``loop``.
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.. code-block:: yaml+jinja
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- name: with_random_choice
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debug:
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msg: "{{ item }}"
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with_random_choice: "{{ my_list }}"
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- name: with_random_choice -> loop (No loop is needed here)
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debug:
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msg: "{{ my_list|random }}"
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tags: random
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