execution output

[vdo023@localhost modify_list]$ ansible-playbook -i "localhost," ./modify_list-playbook.yml

PLAY [localhost] **********************************************************************************************************************************

TASK [modify the list values by appending to the end with _changed] *******************************************************************************
ok: [localhost] => {
    "msg": "before value: [u'listitem_1', u'listitem_2'] after value: [u'listitem_1_changed', u'listitem_2_changed']"
}

TASK [modify the list values by appending to the end with .changed] *******************************************************************************
ok: [localhost] => {
    "msg": "before value: [u'listitem_1', u'listitem_2'] after value: [u'listitem_1.changed', u'listitem_2.changed']"
}

TASK [modify the database value by adding _stg to the first word upto the first dot] **************************************************************
ok: [localhost] => {
    "msg": "before value: test.server.net after value: test_stg"
}

TASK [replace the server address dot values with forward slashes] *********************************************************************************
ok: [localhost] => {
    "msg": "before value: com.test.application:great:1.0:tar after value: com/test/application/great"
}

PLAY RECAP ****************************************************************************************************************************************
localhost                  : ok=4    changed=0    unreachable=0    failed=0

modify_list-playbook.yml

---
- hosts: localhost
  connection: local
  gather_facts: False
  vars:
    my_list:
      - listitem_1
      - listitem_2
    my_database: test.server.net
    my_manifest: "com.test.application:great:1.0:tar"

  tasks:
    - name: modify the list values by appending to the end with _changed
      debug:
        msg: "before value: {{ my_list }} after value: {{ my_list | map('regex_replace', '(.*)', '\\1_changed') | list }}"
    - name: modify the list values by appending to the end with .changed
      debug:
        msg: "before value: {{ my_list }} after value: {{ my_list | map('regex_replace', '^(.*)$', '\\1.changed') | list }}"
    - name: modify the database value by adding _stg to the first word upto the first dot
      debug:
        msg: "before value: {{ my_database }} after value: {{ my_database | regex_replace('([^\\.]*)\\.(.+)$', '\\1') }}_stg"
    - name: replace the server address dot values with forward slashes
      debug:
       msg: "before value: {{ my_manifest }} after value: {{ my_manifest.split(':')[0] | regex_replace('[.]','/') }}/{{ my_manifest.split(':')[1] }}"