Ansible: Insert line if not exists

Question

I\'m trying insert a line in a property file using ansible. I want to add some property if it does not exist, but not replace it if such property already exists in the file.

Answer 1

This is possible by simply using lineinfile and check_mode:

- name: Check if couchbase.host is already defined
  lineinfile:
    state: absent
    path: "/database.properties"
    regexp: "^couchbase.host="
  check_mode: true
  changed_when: false # This just makes things look prettier in the logs
  register: check

- name: Define couchbase.host if undefined
  lineinfile:
    state: present
    path: "/database.properties"
    line: "couchbase.host=127.0.0.1"
  when: check.found == 0