Which module to use to edit files - Ansible - ansible

Question

I want to edit the configuration file of telegraf(system metrics collecting agent).
Telegraf comes in with a default config file which can be edited. There are many input and output plugins defined in there, which are commented out and can be added by removing the comments and also be customized.
I want to edit only some of the plugins defined there, not all of them. For example, consider this is the file,
[global]
interval='10s'
[outputs.influxdb]
host=['http://localhost:8086']
#[outputs.elasticsearch]
# host=['http://localhost:9200']
[inputs.netstat]
interface='eth0'
Now, I want to edit the 3 blocks, global, outputs.influxdb and inputs.netstat. I don't want to edit outputs.elasticsearch but also want that the block outputs.elasticsearch should remain in the file.
When Using Ansible, I firstly used Template module, but if I use that, then the commented data would be lost.
Then I used the ini_file module, instead of editing the already present block, it adds a new block even if it is already present, and results in something like this,
[outputs.influxdb]
host=[http://localhost:8086]
[outputs.influxdb]
host=[http://xx.xx.xx.xx:8086]
Which module is ideal for my scenario ?

Answer 1

There are several options, depending on your purpose.
The lineinfile - module is the best option, if you just want to add, replace or remove one line.
The replace - module is best, if you want to add, replace or delete several lines.
The blockinfile - module can add several lines, surrounded by markers.
If you only want to change two or three lines, you could use as many calls of lineinfile. To change a whole config file, I would recommend, like the commenters suggest, use the template - module.

Answer 2

Ok, if you really really want to avoid using templates, you could try to use replace and a regex like this:
- hosts: local
tasks:
- replace:
path: testfile
regexp: '^\[{{ item.category }}\]\s(.*)host(.*)$'
replace: '[{{ item.category }}]\n host=[{{ item.host }}]'
with_items:
- { category: 'outputs.influxdb', host: 'http://cake.com:8080' }
This, in its current form, would not necessarily handle more than one option under each category, but the regex can be modified to handle multiple lines.
As required, it will not touch the # commented lines. However, if you decide to enable some of the previously inactive sections, you might end up with a slightly messier configuration file that would include the instructions both commented and uncommented (shouldn't impact functionality, only 'looks'). You will also need to account for options that look like the example below (interleaved commented/uncommented values) and create regexes specially for those use-cases:
[section]
option1=['value']
# option2=['value']
option3=['value']
It highly depends on your use-case, but my recommendation remains that templates are to be used instead, as they are a more robust approach, with less chances of things going wrong.