Ansible iterate over a nested list with default values

Question

The goal is to iterate over a list which contains another list. If the nested list is empty I want to use the values of the parent instead. Sadly I can't find a possible solution.

List to iterate:

  users:
    - name: Mario
      username: admin_mario
      state: present
      role: admin
      ssh: []
    - name: luigi
      username: just_luigi
      state: present
      role: qa
      ssh:
          - username: qa_luigi
          role: qa
          state: present
          - username: admin_luigi
          role: admin
          state: present

So I would like to iterate over this list if ssh is empty use username, state and role as defaults.

- name: test
  include_tasks: "mytasks.yml"
  loop: "{{ users|subelements(ssh) }}"
  loop_control:
    loop_var: user
  when: users is defined

- name: test
  include_tasks: "mytasks.yml"
  loop: "{{ users|default({'ssh': [{'username': user.username}]})|subelements('ssh') }}"
  loop_control:
    loop_var: user

Sadly I couldn't figure out a solution with the Dokumentation e.g. with_items, loop control, subelements nothing seems to work as expected.

Answer 1

Create defaults

  defaults: "{{ users|json_query('[].{username: username,
                                      state: state,
                                      role: role}') }}"

gives

  defaults:
  - role: admin
    state: present
    username: admin_mario
  - role: qa
    state: present
    username: just_luigi

Create list of ssh

  ssh_str: |
    {% for i,j in users|zip(defaults) %}
    {% if i.ssh|length == 0 %}
    - ssh: [{{ j }}]
    {% else %}
    - {}
    {% endif %}
    {% endfor %}
  ssh: "{{ ssh_str|from_yaml }}"

---

Optionally,

  ssh_str: |
    {% for i,j in users|zip(defaults) %}
    - {{ i.ssh|ternary({}, {'ssh': [j]}) }}
    {% endfor %}

---

gives

  ssh:
  - ssh:
    - role: admin
      state: present
      username: admin_mario
  - {}

Combine the items of the lists

    - debug:
        msg: "{{ item.0.name }} {{ item.1.username }} {{ item.1.role }} {{ item.1.state }}"
      with_subelements:
        - "{{ users|zip(ssh)|map('combine') }}"
        - ssh

gives (abridged)

  msg: Mario admin_mario admin present
  msg: luigi qa_luigi qa present
  msg: luigi admin_luigi admin present

---

Example of a complete playbook for testing

- hosts: localhost

  vars:

    users:
      - name: Mario
        username: admin_mario
        state: present
        role: admin
        ssh: []
      - name: luigi
        username: just_luigi
        state: present
        role: qa
        ssh:
          - username: qa_luigi
            role: qa
            state: present
          - username: admin_luigi
            role: admin
            state: present

    defaults: "{{ users|json_query('[].{username: username,
                                        state: state,
                                        role: role}') }}"
    ssh_str: |
      {% for i,j in users|zip(defaults) %}
      {% if i.ssh|length == 0 %}
      - ssh: [{{ j }}]
      {% else %}
      - {}
      {% endif %}
      {% endfor %}
    ssh: "{{ ssh_str|from_yaml }}"

  tasks:

    - debug:
        var: defaults
    - debug:
        var: ssh

    - debug:
        msg: "{{ item.0.name }} {{ item.1.username }} {{ item.1.role }} {{ item.1.state }}"
      with_subelements:
        - "{{ users|zip(ssh)|map('combine') }}"
        - ssh