Ansible: Use inventory_hostname variable in lineinfile module

Question

I'm using Ansible 2.7.9 and I'm having trouble with the regex definition in the lineinfile module. My file has the following line:

host.example.com = /path/to/a/directory

I want to remove that line. As {{ inventory_hostname }} contains dots, I'm trying to escape those with replace. The task in my playbook looks like this:

- name: Remove LE webroot definition
    lineinfile: 
      path: "/etc/path/to/config/{{ inventory_hostname }}.conf"
      regexp: "^{{ inventory_hostname | replace('.', '\.') }} = /path/to/a/directory"
      state: absent

When I'm executing the playbook, the following error occurs:

[...]
The offending line appears to be:
      path: "etc/path/to/config/{{ inventory_hostname }}.conf"
      regexp: "^{{ inventory_hostname | replace('.', '\.') }} = /path/to/a/directory"
                                                      ^ here
We could be wrong, but this one looks like it might be an issue with
missing quotes.  Always quote template expression brackets when they
start a value. For instance:
[...]

As you can see, I'm using the double quotes, and all examples that I've found are using this syntax. What I'm doing wrong here? Thanks for any help.

Answer 1

The issue seems resolved, If I escape the backslash in the regex too:

- name: Remove LE webroot definition
    lineinfile: 
      path: "/etc/path/to/config/{{ inventory_hostname }}.conf"
      regexp: "^{{ inventory_hostname | replace('.', '\\.') }} = /path/to/a/directory"
      state: absent