Trying to extract fields from a hybrid log Syslog/JSON nested logs

atme — Tue, 05 Aug 2025 00:19:10 GMT

Trying to extract some data from a hybrid log where the log format is <Syslog header> <JSON Data>.

Have had success with extracting via spath and regex in search but want to do this before ingestions, so trying to complete this on a heavy forwarder by using props.conf and transforms.conf to complete the field extractions. Got this working to a degree but it only functions partly fuctions with some logs the the nested logs in msg are not full extracted and some logs don't extract anything for JSON.

An example of one of many log types but all in this format <Syslog header> <JSON Data>

Aug 3 04:45:01 server.name.local program {"_program":{"uid":"0","type":"newData","subj":"unconfined","pid":"4864","msg":"ab=new:session_create creator=sam,sam,echo,ba_permit,ba_umask,ba_limits acct=\"su\" exe=\"/usr/sbin/vi\" hostname=? addr=? terminal=vi res=success","auid":"0","UID":"user1","AUID":"user1"}}

creator=sam
stopping at first comma

acct=\
exe=\
Doesn't collect the data after \

And the following 2 logs had no field extractions from the json

Aug 3 04:31:01 server.name.local program {"_program":{"uid":"0","type":"SYSCALL","tty":"pts1","syscall":"725","su":"0","passedsuccess":"yes","pass":"unconfined","id":"0","sess":"3417","pid":"4568732","msg":"utime(1754195461.112:457):","items":"2","gid":"0","fsuid":"0","fsgid":"0","exit":"3","exe":"/usr/bin/vi","euid":"0","egid":"0","comm":"vi","auid":"345742342","arch":"c000003e","a3":"1b6","a2":"241","a1":"615295291b60","a0":"ffffff9c","UID":"user1","SYSCALL":"openmat","SUID":"user1","SGID":"user1","GID":"user1","FSUID":"user1","FSGID":"user1","EUID":"user1","EGID":"user1","AUID":"user1","ARCH":"x86_64"}} Aug 3 04:10:01 server.name.local program {"_program":{"type":"data","data":"/usr/bin/vi","msg":"utime(1754194201.112:457):"}}

Thanks in advance for any help

Re: Trying to extract fields from a hybrid log Syslog/JSON nested logs

tej57 — Mon, 11 Aug 2025 11:19:00 GMT

Hey @atme,

It would be complex if you try to extract all of these fields at index time. The computational load would also increase. I would prefer going for search time extractions. However, if you still wish to extract fields at index time, it would be great if you can share what you've configured till now in props and transforms. Since the _raw event varies in number of fields also, we need to define a regex based pattern or key-value pair to extract the fields.

Thanks,
Tejas.

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Trying to extract fields from a hybrid log Syslog/JSON nested logs

Re: Trying to extract fields from a hybrid log Syslog/JSON nested logs