Ansible add a line in file - ansible

Question

I am trying to add a new line in a file through ansible lineinfile module. Below is the task defined in the playbook.
lineinfile:
path: /etc/httpd/file.conf
line: myfilecontent
It works fine and add a new line in the file. But when i modify the line content to some another value i.e mynewfilecontent it adds another line instead of updating it.
lineinfile:
path: /etc/httpd/file.conf
line: mynewfilecontent
Help is appreciated.
Thanks

Answer 1

Use the state parameter of lineinfile module and create the structure below
my_lines:
- line: myfilecontent
state: absent
- line: mynewfilecontent
state: present
The state parameter controls if the line is present, or absent in the file. See the example below
- hosts: localhost
vars:
my_lines:
- line: myfilecontent
state: absent
- line: mynewfilecontent
state: present
tasks:
- lineinfile:
path: /tmp/test.conf
create: yes
line: "{{ item.line }}"
state: "{{ item.state }}"
loop: "{{ my_lines }}"
Note 1.
The structure can be simplified by adding the state parameter only if the line is absent
my_lines:
- line: myfilecontent
state: absent
- line: mynewfilecontent
Declare default state present in the loop
state: "{{ item.state|default('present') }}"
Note 2.
The default state, defined in the module, is present, hence the state parameter may be omitted if not present in the data structure
state: "{{ item.state|default(omit) }}"
All 3 variations above are functionally equivalent.

Answer 2

If you want your line to potentially replace an existing line in the file then you need to provide a regexp argument to the lineinfile module.
The regular expression to look for in every line of the file.
For state=present, the pattern to replace if found. Only the last line found will be replaced.
For state=absent, the pattern of the line(s) to remove.
If the regular expression is not matched, the line will be added to the file in keeping with insertbefore or insertafter settings.
When modifying a line the regexp should typically match both the initial state of the line as well as its state after replacement by line to ensure idempotence.
The last line which matches your regexp will be replaced with your line value; if there is no match then a new line will be added.
Without a regexp argument the module will just check for an exact match to your line value.
See https://docs.ansible.com/ansible/latest/modules/lineinfile_module.html.