Regex a Block of Yaml Data - regex

Question

Im currently using regex101 to try and work out the following, id like to be able to capture a full items data for example name_template_2 and its associated description, define and write data
Here's my data model
templates:
name_template:
description: test_description
define: yes
write: true
name_template_2:
description: test_description2
define: false
write: true
I can capture the lines I need with the following
^[[:space:]][[:space:]][[:space:]][[:space:]].*
and
^[[:space:]][[:space:]]name_template_2:
but I am unable to join both patterns together to filter just the key and data related to name_template_2. The more I read online the more I understand it less. Has anyone achieved this before or is there a much more efficient way of doing this?

Answer 1

Using 2 capture groups:
^[^\S\n]{2}(name_template_2:)((?:\n[^\S\n]{4}\S.*)+)
Explanation
^ Start of string
[^\S\n]{2} Match 2 spaces without newlines
(name_template_2:) Match the string and capture in group 1
( Capture group 2
(?: Non capture group
\n Match a newline
[^\S\n]{4} Match 4 spaces without newlines
\S.* Match a non whitespace char and the rest of the line
)+ Repeat the non capture group 1 or more times
) Close group 2
Regex demo

Answer 2

I suggest using a structure-aware tool like yq to manipulate YAML and not using regular expressions.
#!/bin/bash
INPUT='
templates:
name_template:
description: test_description
define: yes
write: true
name_template_2:
description: test_description2
define: false
write: true
'
echo "$INPUT" | yq '{"name_template_2": .templates.name_template_2}'
Output
name_template_2:
description: test_description2
define: false
write: true