How to debug the logstash file plugin

If you want to debug the process itself you may run it like this

/opt/logstash/bin/logstash -f yourconf.conf -v --debug --verbose

NOTE: According to @neeraj-gupta using --debug and --verbose at the same time may cause a problem when trying to see debug logs of cloudwatch and using only --debug is enough.

So realistically something like this is more apt:

/opt/logstash/bin/logstash -f yourconf.conf --debug

In new version stdout format changed

stdout { codec => rubydebug }