Feature Request

Adding this option enables the parser to process metadata included before the CSV header.
This information can be included in every metric as a field or tag.

Proposal:

To add two new options to the CSV parser: csv_metadata_rows and csv_metadata_regex
csv_metadata_rows = x where x is the number of rows that contain the metadata after csv_skip_rows and before the header rows. By default, this value would be set to zero.

csv_metadata_regex = ["^[#]?\s*(?P<key>[^:=]+)[:=]\s*(?P<value>\w+)$"]

csv_metadata_regex is a list of regex expressions, each regex must have a key and value label.

The regex expression above covers the following scenarios:

# comment line
#	option 1: value1
	option 2= value2

	# another comment line
	option3: value3

and returns the following metadata:
option 1=value1
option 2=value2
option3=value3

Note that the regex could also be used to ignore comments.

Example CSV file:

version=1.0
file created: 2021-10-08T12:34:18+10:00
timestamp,type,name,status
2020-11-23T08:19:27+10:00,Reader,R002,1
2020-11-04T13:23:04+10:00,Reader,R031,0
2020-11-04T13:29:47+10:00,Coordinator,C001,1

Current behaviour:

The current parser does not support metadata parsing. These rows need to be skipped.

Desired behaviour:

The output should include version and file created as either a tag or a field for every metric following the header.