Persistent values between events from the same filebeat source file


#1

I need some help with an issue I am having. It is not necessarily a Logstash issue, but rather an issue with the processing logic. I am using Filebeat to send the logs to Logstash for further processing. The log lines are not multiline.

An example log file looks like this:
"XY51661R 200 SOME TEXT More Info / extra-string AAAA 00:20 all 2:55 Page 1 "
"From user : test user filenumber . . . : aaaa/bbbb/cccc 23.11.2018 1.0 "
"------------------------------------------------------------------------------------------------------------------------------------ "
"Series 1 / 2 Prog ProgM Start End Duration Status "
"------------------------------------------------------------------------------------------------------------------------------------ "
" 300 200 ABC0400C Main 2:55:20 2:55:22 0:02 Normal termination "
" 300 300 ABC0200C Secondary 2:55:22 2:55:30 0:08 Normal termination "
"End of print 8'888 "

So since the logs are being sent on a per-line basis, single log lines do not contain all of the required information. The second line contains the current date of the job (23.11.2018). I need to somehow "save" this value to use across all incoming events for the current logfile. I have managed to semi do this, by tagging each line based on the grok match. The match for the second line containing the date adds a unique tag to the line (2headline). When normal job events are matched (" 300 300 ABC0200C Secondary 2:55:22 2:55:30 0:08 Normal termination "), the date value is retrieved by the Elasticsearch filter plugin and added to a new field in the job event.

This approach has a major flaw:
The events/log lines are being processed asynchronously, so I would need to make sure the file is sent top-to-bottom and processed by Logstash in the same order.

How would one do this?