ansible.builtin.subelements lookup – traverse nested key from a list of dictionaries

Note

This lookup plugin is part of ansible-core and included in all Ansible installations. In most cases, you can use the short plugin name subelements even without specifying the collections: keyword. However, we recommend you use the FQCN for easy linking to the plugin documentation and to avoid conflicting with other collections that may have the same lookup plugin name.

Synopsis

  • Subelements walks a list of hashes (aka dictionaries) and then traverses a list with a given (nested sub-)key inside of those records.

Terms

Parameter

Comments

Terms

string / required

tuple of list of dictionaries and dictionary key to extract

Keyword parameters

This describes keyword parameters of the lookup. These are the values key1=value1, key2=value2 and so on in the following examples: lookup('ansible.builtin.subelements', key1=value1, key2=value2, ...) and query('ansible.builtin.subelements', key1=value1, key2=value2, ...)

Parameter

Comments

skip_missing

string

Lookup accepts this flag from a dictionary as optional. See Example section for more information.

If set to True, the lookup plugin will skip the lists items that do not contain the given subkey.

If set to False, the plugin will yield an error and complain about the missing subkey.

Default: false

Notes

Note

  • When keyword and positional parameters are used together, positional parameters must be listed before keyword parameters: lookup('ansible.builtin.subelements', term1, term2, key1=value1, key2=value2) and query('ansible.builtin.subelements', term1, term2, key1=value1, key2=value2)

Examples

- name: show var structure as it is needed for example to make sense
  hosts: all
  vars:
    users:
      - name: alice
        authorized:
          - /tmp/alice/onekey.pub
          - /tmp/alice/twokey.pub
        mysql:
            password: mysql-password
            hosts:
              - "%"
              - "127.0.0.1"
              - "::1"
              - "localhost"
            privs:
              - "*.*:SELECT"
              - "DB1.*:ALL"
        groups:
          - wheel
      - name: bob
        authorized:
          - /tmp/bob/id_rsa.pub
        mysql:
            password: other-mysql-password
            hosts:
              - "db1"
            privs:
              - "*.*:SELECT"
              - "DB2.*:ALL"
  tasks:
    - name: Set authorized ssh key, extracting just that data from 'users'
      ansible.posix.authorized_key:
        user: "{{ item.0.name }}"
        key: "{{ lookup('file', item.1) }}"
      with_subelements:
         - "{{ users }}"
         - authorized

    - name: Setup MySQL users, given the mysql hosts and privs subkey lists
      community.mysql.mysql_user:
        name: "{{ item.0.name }}"
        password: "{{ item.0.mysql.password }}"
        host: "{{ item.1 }}"
        priv: "{{ item.0.mysql.privs | join('/') }}"
      with_subelements:
        - "{{ users }}"
        - mysql.hosts

    - name: list groups for users that have them, don't error if groups key is missing
      ansible.builtin.debug: var=item
      loop: "{{ q('ansible.builtin.subelements', users, 'groups', {'skip_missing': True}) }}"

Return Value

Key

Description

Return value

string

list of subelements extracted

Returned: success

Authors

  • Serge van Ginderachter

Hint

Configuration entries for each entry type have a low to high priority order. For example, a variable that is lower in the list will override a variable that is higher up.