conf.yml

- name: Configure telegraf {{name}}
  template:
    src: "{{ src }}"
    dest: "{{ dest }}"
    owner: root
    group: "{{ telegraf_group }}"
    mode: 0640
  notify: reload telegraf

# mark for prune
- name: Touch telegraf {{name}} for prune
  shell: "test -f {{ dest }} && touch {{ dest }}"
  check_mode: no # always run
  changed_when: false
  failed_when: false

main.yml

- name: Configure telegraf agent
  include_tasks: conf.yml
  vars:
    name: telegraf.conf
    src: telegraf.conf.j2
    dest: /etc/telegraf/telegraf.conf

- ...

# relies on conf.yml touching each file
- name: Prune old configs
  command: find /etc/telegraf/telegraf.d/ -type f -not -newer /etc/telegraf/telegraf.conf {% if not ansible_check_mode %}-delete {% endif %}-print
  check_mode: no # always run, but without -delete if check_mode
  register: prune_telegraf_configs
  changed_when: prune_telegraf_configs.stdout_lines
  notify: reload telegraf