Only check whether a line present in a file (ansible)

Question

In ansible, I need to check whether a particular line present in a file or not. Basically, I need to convert the following command to an ansible task. My goal is to only che

Answer 1

User robo's regexp & absent method is quite clean, so I've fleshed it out here for easy use and added improvements from comments by @assylias and @Olivier:

- name: Ensure /tmp/my.conf contains 127.0.0.1
  lineinfile:
    path: /tmp/my.conf
    regexp: '^127\.0\.0\.1.*whatever'
    state: absent
  check_mode: yes
  changed_when: false
  register: out

- debug:
    msg: "Yes, line exists."
  when: out.found

- debug:
    msg: "Line does NOT exist."
  when: not out.found