Parsing multiline stacktrace logstash

Question

I am trying to parse custom log messages which also have error stacktraces that span multiple lines. My GROK pattern fails to parse if its a multiline stacktrace and all i see in the elasticsearc index is the first line of the message. Strangely if I use a parser like grokdebugger to test the pattern works for multiline as well. What am I missing in the logstash config

Following is the snippet of my grok pattern in logstash:

grok {match => [
        "message" , "%{TIMESTAMP_ISO8601:timestamp} \[%{SPACE}%{DATA:loglevel}\] %{DATA:class} \[%{DATA:operation}\] \(user=%{DATA:userid}\) (?m)%{GREEDYDATA:stacktrace}"
        ]
}

Sample message that gets parsed:

2018-01-09 21:38:21,414 [    INFO]  abc.xyz.def:444: [Put] [Protect] (user=xyz) Random Message

Message that does not get parsed:

2018-01-09 21:38:21,415 [   ERROR]  abc.xyz.def:41: [Error] (user=xyz) Unhandled exception encountered...
Traceback (most recent call last):
  File "/usr/local/lib/abc/xyz.py", line 113, in some_requestrv = self.dispatch_request() 

Answer 1

You can indeed use multiline codec, in your case:

input {
  file {
    path => "/var/log/someapp.log"
    codec => multiline {
      # Grok pattern names are valid! :)
      pattern => "^%{TIMESTAMP_ISO8601} "
      negate => true
      what => "previous"
    }
  }
}

Here is the link for documentation