ansible - example of using selectattr to filter on attrs that are defined and true

00_play.yml

---
- hosts: localhost
  connection: local
  gather_facts: False
  vars:
    apache2_vhosts:
      - name: "stage.example.org"
        docroot: "/var/www/stage1"
      - name: "stage2.example.org"
        docroot: "/var/www/stage2"
        letsencrypt: no
      - name: "www.example.org"
        docroot: "/var/www/www"
        letsencrypt: yes
  tasks:
    - debug:
        msg: "{{ apache2_vhosts | selectattr('letsencrypt', 'defined') | selectattr('letsencrypt', 'equalto', True) | list }}"

01_output

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

TASK [debug] **************************************************************************************************************************
ok: [localhost] => {
    "changed": false,
    "msg": [
        {
            "docroot": "/var/www/www",
            "letsencrypt": true,
            "name": "www.example.org"
        }
    ]
}

PLAY RECAP ****************************************************************************************************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=0