---
- name: Playbook for testing lineinfile with regex
  hosts: localhost
  tasks:
    - name: Replace values in yml file
      lineinfile:
        backup: no
        backrefs: yes
        state: present
        path: ./my.yml
        regexp: '^(\s*)[#]?{{ item.search }}(: )*'
        line: '\1{{ item.replace }}'
      with_items:
        - { search: 'key1', replace: 'key1: NEWvalue1' }
        - { search: 'key2', replace: 'key2: NEWvalue2' }
        - { search: '\- elephant', replace: '- heffalump' }
        - { search: '\- www.ansible.com', replace: '- www.redhat.com' }

    - name: add item to yml file at correct indentation level
      lineinfile:
        backup: no
        backrefs: yes
        state: present
        path: ./my.yml
        regexp: '^(\s*)[#]?{{ item.search }}(.*)'
        line: '\1{{ item.search }}\2\n\1{{ item.add }}'
      with_items:
        - { search: 'key2', add: 'key3: INSvalue3' }
        - { search: '- cat', add: '- deer' }