regex ansible lineinfile subsection - regex

Question

I am fairly new to ansible and have been solving the following problem with a shell script, but the proper way I believe is to use the lineinfile module, just not sure how to accomplish this.
Let's say I have a file with the following text in it.
<cpu>
<alarm>
active = yes
</alarm>
</cpu>
<disk>
<alarm>
active = yes
<fixed>
<#>
active = yes
description = File system /
<inode_error>
active = yes
threshold = 2
message = InodeError
</inode_error>
</#>
<#boot>
active = yes
description = File system /boot
percent = yes
<error>
active = yes
threshold = 5
message = DiskError
</error>
</#boot>
</fixed>
</alarm>
</disk>
I want to make sure the following section is set correctly.
<disk><alarm><fixed><#boot><error>"threshold = 2"</error></#boot></fixed></alarm></disk>
is there a way to only (modify/make sure exists) that line, normally this file is much larger with many more sections, but I erased some so the question is readable.
Update: Modifying this as it is not valid XML and the XML module will not parse the file correctly.
Thanks!

Answer 1

lineinfile scans file per line, so you can't define complex multiline regexp for context definition.
replace module support multiline regexp.
If you have threshold = X in the file and want to be sure it is set to specific value, you can use this regexp:
- replace:
path: ./test.txt
regexp: '(<disk>[\s\S]*<alarm>[\s\S]*<#boot>[\s\S]*<error>[\s\S]*)(threshold\s*=\s*\d+)([\s\S]*?<\/error>)'
replace: '\1threshold = 2\3'
It searches for line threshold\s*=\s*\d+ inside <disk>...<alarm>...<#boot>...<error>....
This code is idempotent – so if threshold = 2, then nothing is done.
But if there is no threshold = X string, it will fail. You should construct more complex regular expression for that case.

Answer 2

you could use the lineinfile module (http://docs.ansible.com/ansible/latest/lineinfile_module.html) where you could write a regex to modify/add the line and use the validate function to run a command to ensure that the xml file has the proper syntax.
If you are on Ansible 2.4 you can use the xml module (https://docs.ansible.com/ansible/2.4/xml_module.html) and use the attribute parameter to check if the xpath in xml file is set, like that:
- name: Read attribute value
xml:
path: /foo/bar.xml
xpath: /business/website/validxhtml
content: attribute
attribute: validatedon
register: xmlresp
regards