Fluentd Parsing - regex

Question

Hi i'm trying to parse single line log using fluentd. Here is log i'm trying to parse.
F2:4200000000000000,F3:000000,F4:000000060000,F6:000000000000,F7:000000000,F8..........etc
This will parse into like this:
{ "F2" : "4200000000000000", "F3" : "000000", "F4" : "000000060000" ............etc }
I tried to use regex but it's confusing and making me write multiple regexes for different keys and values. Is there any easier way to achieve this ?
EDIT1: Heya! I will make this more detailed. I'm currently tailing logs using fluentd to Elasticsearch+Kibana. Here is unparsed example log that fluentd sending to Elasticsearch:
21/09/02 16:36:09.927238: 1 frSMS:0:13995:#HTF4J::141:141:msg0210,00000000000000000,000000,000000,007232,00,#,F2:00000000000000000,F3:002000,F4:000000820000,F6:Random message and strings,F7:.......etc
Elasticsearch recived message:
{"message":"frSMS:0:13995:#HTF4J::141:141:msg0210,00000000000000000,000000,000000,007232,00,#,F2:00000000000000000,F3:002000,F4:000000820000,F6:Random
digits and chars,F7:.......etc"}
This log has only message key so i can't index and create dashboard on only using whole message field. What am i trying to achieve is catch only useful fields, add key into it if it has no key and make indexing easier.
Expected output:
{"logdate" : "21/09/02 16:36:09.927238",
"source" : "frSMS",
"UID" : "#HTF4J",
"statuscode" : "msg0210",
"F2": "00000000000000000",
"F3": "randomchar314516",.....}
I used regex plugin to parse into this but it was too overwhelming and . Here is what i did so far:
^(?<logDate>\d{2}.\d{2}.\d{2}\s\d{2}:\d{2}:\d{2}.\d{6}\b)....(?<source>fr[A-Z]{3,4}|to[A-Z]{3,4}\b).(?<status>\d\b).(?<dummyfield>\d{5}\b).(?<HUID>.[A-Z]{5}\b)..(?<d1>\d{3}\b).(?<d2>\d{3}\b).(?<msgcode>msg\d{4}\b).(?<dummyfield1>\d{16}\b).(?<dummyfield2>\d{6}\b).(?<dummyfield3>\d{6,7}\b).(?<dummyfield4>\d{6}\b).(?<dummyfield5>\d{2}\b)...
Which results to :
"logDate": "21/09/02 16:36:09.205706",
"source": "toSMS" ,
"status": "0",
"dummyfield": "13995" ,
"UID" : "#HTFAA" ,
"d1" : "156" ,
"d2" : "156" ,
"msgcode" : "msg0210",
"dummyfield1" :"0000000000000000" ,
"dummyfield2" :"002000",
"dummyfield3" :"2000000",
"dummyfield4" :"00",
"dummyfield5" :"2000000" ,
"dummyfield6" :"867202"
Which only applies to example log and has useless fields like field1, dummyfield, dummyfield1 etc.
Other logs has the useful values and keys(date,source,msgcode,UID,F1,F2 fields) like i showcased on expected output. Not useful fields are not static(they can be none, or has less|more digits and chars) so they trigger the pattern not matched error.
So the question is:
How do i capture useful fields that i mentioned using regex?
How do i capture F1,F2,F3...... fields that has different value
patterns like char string mixed?
PS: I wraped the regex i wrote into html snippet so the <> capturing fields don't get deleted

Answer 1

Regex pattern to use:
(F[\d]+):([\d]+)
This pattern will catch all the 'F' values with whatever digit that comes after - yes even if it's F105 it still works. This whole 'F105' will be stored as the first group in your regex match expression
The right part of the above pattern will catch the value of all the digits following ':' up until any charachter that is not a digit. i.e. ',', 'F', etc.. and will store it as the second group in your regex match
Use
Depending on your coding language you will have to access your regex matches variable with an iterator and extract group 1 and group 2 respectivly
Python example:
import re
log = 'F2:4200000000000000,F3:000000,F4:000000060000,F6:000000000000,F7:000000000,F105:9726450'
pattern = '(F[\d]+):([\d]+)'
matches = re.finditer(pattern,log)
log_dict = {}
for match in matches:
log_dict[match.group(1)] = match.group(2)
print(log_dict)
Output
{'F2': '4200000000000000', 'F3': '000000', 'F4': '000000060000', 'F6': '000000000000', 'F7': '000000000', 'F105': '9726450'}

Answer 2

Assuming the logdate will be static(in pattern wise) You can ignore useless values using ".+" regex and get collect the useful values by their patterns. So the regex will be like this :
(?\d{2}.\d{2}.\d{2}\s\d{2}:\d{2}:\d{2}.\d{6}\b).+(?fr[A-Z]{3,4}|to[A-Z]{3,4}).+(?#[A-Z0-9]{5}).+(?msg\d{4})
And output will be like:
{"logdate" : "21/09/02 16:36:09.927238", "source" : "frSMS",
"UID" : "#HTF4J","statuscode" : "msg0210"}
And I'm working on getting F2,F3,FN keys and values.