Ansible Deleting matching IPs from hosts file using regex

Question

I'm just trying to change the hostname of the remote node using:

- name: Change the hostname
  lineinfile: dest=/etc/hosts
              regexp='.*{{ item }}$'
              line="{{ hostvars[item].ansible_default_ipv4.address }} {{ LOCAL_HOSTNAME }} {{ LOCAL_HOSTNAME }}.{{ LOCAL_DOMAIN_NAME }}"
              state=present
  when: hostvars[item].ansible_default_ipv4.address is defined
  with_items: "{{ groups['dbservers'] }}"

All this does is add IP hostname FQDN at the end of /etc/hosts file. But I'm want it to remove the existing entry and add new one. This is what I tried so far:

    - name: Change the hostname
      lineinfile: dest=/etc/hosts
#                  regexp='.*{{ item }}$'
                  regexp='{{ hostvars[item].ansible_default_ipv4.address }}'
                  state=absent
#                  line="{{ hostvars[item].ansible_default_ipv4.address }} {{ LOCAL_HOSTNAME }} {{ LOCAL_HOSTNAME }}.{{ LOCAL_DOMAIN_NAME }}"
#                  state=present
      when: hostvars[item].ansible_default_ipv4.address is defined
      with_items: "{{ groups['dbservers'] }}"

But this error comes if I run this:

The offending line appears to be:
#                  regexp='.*{{ item }}$'
                  regexp="{{ hostvars[item].ansible_default_ipv4.address }}"
                  ^ here
We could be wrong, but this one looks like it might be an issue with
missing quotes.

Am I doing the right thing or there some other way to achieve this?

P.S. I've tried adding "to" but that didn't help either.

Answer 1

Ansible notation isn't the same as YAML where you can use equal signs. Your problem isn't quoting but you inserted comments at the wrong place. Try this syntax which is valid:

- name: Change the hostname
  lineinfile:
    dest: /etc/hosts
    # regexp: '.*{{ item }}$'
    regexp: '{{ hostvars[item].ansible_default_ipv4.address }}'
    state: absent
    # line: "{{ hostvars[item].ansible_default_ipv4.address }} {{ LOCAL_HOSTNAME }} {{ LOCAL_HOSTNAME }}.{{ LOCAL_DOMAIN_NAME }}"
    # state: present
  when: hostvars[item].ansible_default_ipv4.address is defined
  with_items: "{{ groups['dbservers'] }}"