Add filter keep_keys

[vbotka]

Summary

Create filter keep_keys.

The collection ansible.utils provides the filter keep_keys. Unfortunately:

• It is not working properly. See keep_keys doesn't exclude a key if the value is list. ansible.utils#353
• The documentation is poor. For example, it is not clear what "recursively" means in "Keep specific keys from a data recursively"
• There are only two examples and two tests. An example of "matching_parameter=regex" is missing. It is unclear whether the parameter target should be a list for regex. A list of regex(es) would be an antipattern.
• But, the main hurdle to fix this filter is the class AnsibleArgSpecValidator that is used in all ansible.utils/plugins. Such complexity is inefficient in a filter where a couple of comprehensions would do the job. This also violates the golden Unix rule Tools, not policy

The goal is to keep the code simple and test it properly.

Issue Type

Feature Idea

Component Name

community.genera.keep_keys

Additional Information

  t: [k0, k1]
  l1:
    - {k0: A, k1: B, k2: C}
    - {k0: D, k1: E, k2: F}
  r1: "{{ l1 | community.general.keep_keys(target=t) }}"

gives

  r1:
  - k0: A
    k1: B
  - k0: D
    k1: E

Code of Conduct

• I agree to follow the Ansible Code of Conduct

[ansibullbot]

Files identified in the description:
None

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[vbotka]

This feature request is implemented in PR #8456