Why does this ansible lineinfile task always trigger a notify?

Question

The following task always triggers a notify

The first time it runs ansible applies the change which is expected, and the line is changed. If I run it again, ansible considers it as "changed", even though the regex cannot possibly match, since the line has become "bind-address = 0.0.0.0"

why ?

  - name: Ensure MySQL will listen on all ip interfaces (bind to 0.0.0.0)
    lineinfile: dest=/etc/mysql/my.cnf
      regexp='bind-address\s*=\s*127\.0\.0\.1\s*'
      line='bind-address   = 0.0.0.0'
      state=present
      insertafter=EOF
    notify: restart mysql

Answer 1

Refer to the backrefs option of the lineinfile module. Specifically, "if the regexp doesn't match anywhere in the file, the file will be left unchanged." A working play would look like this:

- name: Ensure MySQL will listen on all ip interfaces (bind to 0.0.0.0)
  lineinfile: dest=/etc/mysql/my.cnf
    regexp='bind-address\s*=\s*127\.0\.0\.1\s*'
    line='bind-address   = 0.0.0.0'
    state=present
    backrefs=yes
  notify: restart mysql