timestamp extraction from json

[Ekino]

Hi Splunk Gurus

Could you someone help me to resolve my Issue with timestamp extraction?

The Issue is that when I want to create a sourcetype with custom timestamp via advanced configuration

where I defined TIME_PREFIX as regular expression ^(?:[^\}\n]*\}){4},\{"\w+":"(?P<timestamp_ex>[^"]+) then timesstamp extraction is not working and I getting  error "failed to parse timestamp. Defaulting to file modtime."

regular expresion I got from splunk field extraction. Why Splunk doesn't accept my regex which was generated by Slunk itself? and tested out via regex101.com where the expression is working.

[Ekino]

Thanks for your answer, it was helpfull

[richgalloway · Accepted solution]

The TIME_PREFIX setting does not tell Splunk how to extract the timestamp field.  It merely tells Splunk where to *find* the timestamp.  The regex should describe the text that comes right before the timestamp.  There's no need for capture groups. 

As is normally the case with the Splunk field extractor, the regex it generates is overly verbose.  It's rarely necessary to describe everything from the beginning of the event until the timestamp - all you need is just enough to find the timestamp.