Add a command output to a file from ansible lineinfile module - module

Question

I'm trying to write a ansible task to incorporate the output of below command into /etc/lvm/lvm.conf file:
[root#ansible]# vgs --noheadings -o vg_name
my_vg
rhel_home
rhel_root
The above mentioned values need to be added as below:
volume_list = [ "rhel_root", "rhel_home", "my_vg" ]
In the managed nodes, the above paramater will be as below:
# volume_list = [ "vg1", "vg2/lvol1", "#tag1", "#*" ]
Kindly help me to proceed further as I'm stuck here:
- name: Fetch the Volume group
shell: "vgs --noheadings -o vg_name"
register: vgs
- debug:
msg: "{{ vgs.stdout }}"
- name: Line in file
lineinfile:
path: /tmp/lvm.conf
regex: "volume_list = .*"
line: "volume_list = [ vgs.stdout_lines ]"
It is adding a line as below, without double quotes in the vg name:
volume_list = [ vgs.stdout_lines ]
at the bottom and not replacing the below line:
volume_list = [ "vg1", "vg2/lvol1", "#tag1", "#*" ]
Need assistance to get output as
volume_list = [ "rhel_root", "rhel_home", "my_vg" ]

Answer 1

For your purpose, you need to use the {{ vgs.stdout_lines }} list (not \"vgs.stdout_lines\" string) variable in your lineinfile task.
Like:
line: "volume_list = {{ vgs.stdout_lines | to_json }}"
Though, I noticed that the VG Names returned by command have preceding whitespace like " rhel_root". So it might be a good idea to set_fact another variable which has the unnecessary whitespace trimmed.
- command: vgs --noheadings -o vg_name
register: vgs
- set_fact:
volume_list: "{{ volume_list | default([]) + [ item | trim ] }}"
loop: "{{ vgs.stdout_lines }}"
- lineinfile:
path: /tmp/lvm.conf
regexp: '# volume_list ='
line: 'volume_list = {{ volume_list | to_json }}'