Thanks for the reply mate @Badger .
So now I am convinced that I should be using the "read" mode.
I killed logstash process and tried to start it again. But now it doesn't read any files.
I tried removing the ignore_older and still no help.
In the debug logs this is what I see:-
[2019-05-14T19:38:25,763][DEBUG][logstash.agent ] Converging pipelines state {:actions_count=>0}
[2019-05-14T19:38:26,218][DEBUG][logstash.outputs.file ] Starting stale files cleanup cycle {:files=>{}}
[2019-05-14T19:38:26,218][DEBUG][logstash.outputs.file ] 0 stale files found {:inactive_files=>{}}
[2019-05-14T19:38:26,646][DEBUG][logstash.outputs.file ] Starting flush cycle
[2019-05-14T19:38:27,370][DEBUG][logstash.instrument.periodicpoller.cgroup] One or more required cgroup files or directories not found: /proc/self/cgroup, /sys/fs/cgroup/cpuacct, /sys/fs/cgroup/cpu
[2019-05-14T19:38:27,635][DEBUG][org.logstash.execution.PeriodicFlush] Pushing flush onto pipeline.
[2019-05-14T19:38:28,134][DEBUG][logstash.instrument.periodicpoller.jvm] collector name {:name=>"ParNew"}
[2019-05-14T19:38:28,134][DEBUG][logstash.instrument.periodicpoller.jvm] collector name {:name=>"ConcurrentMarkSweep"}
[2019-05-14T19:38:28,646][DEBUG][logstash.outputs.file ] Starting flush cycle
[2019-05-14T19:38:28,762][DEBUG][logstash.config.source.local.configpathloader] Skipping the following files while reading config since they don't match the specified glob pattern {:files=>["/usr/share/logstash/CONTRIBUTORS", "/usr/share/logstash/Gemfile", "/usr/share/logstash/Gemfile.lock", "/usr/share/logstash/LICENSE.txt", "/usr/share/logstash/NOTICE.TXT", "/usr/share/logstash/bin", "/usr/share/logstash/config", "/usr/share/logstash/data", "/usr/share/logstash/lib", "/usr/share/logstash/logs", "/usr/share/logstash/logstash-core", "/usr/share/logstash/logstash-core-plugin-api", "/usr/share/logstash/modules", "/usr/share/logstash/tools", "/usr/share/logstash/vendor", "/usr/share/logstash/x-pack"]}
[2019-05-14T19:38:28,762][DEBUG][logstash.config.source.local.configpathloader] Reading config file {:config_file=>"/usr/share/logstash/LogStash.conf"}
[2019-05-14T19:38:28,764][DEBUG][logstash.agent ] Converging pipelines state {:actions_count=>0}
[2019-05-14T19:38:30,647][DEBUG][logstash.outputs.file ] Starting flush cycle
[2019-05-14T19:38:31,762][DEBUG][logstash.config.source.local.configpathloader] Skipping the following files while reading config since they don't match the specified glob pattern {:files=>["/usr/share/logstash/CONTRIBUTORS", "/usr/share/logstash/Gemfile", "/usr/share/logstash/Gemfile.lock", "/usr/share/logstash/LICENSE.txt", "/usr/share/logstash/NOTICE.TXT", "/usr/share/logstash/bin", "/usr/share/logstash/config", "/usr/share/logstash/data", "/usr/share/logstash/lib", "/usr/share/logstash/logs", "/usr/share/logstash/logstash-core", "/usr/share/logstash/logstash-core-plugin-api", "/usr/share/logstash/modules", "/usr/share/logstash/tools", "/usr/share/logstash/vendor", "/usr/share/logstash/x-pack"]}
[2019-05-14T19:38:31,762][DEBUG][logstash.config.source.local.configpathloader] Reading config file {:config_file=>"/usr/share/logstash/LogStash.conf"}
[2019-05-14T19:38:31,764][DEBUG][logstash.agent ] Converging pipelines state {:actions_count=>0}
No events are being processed and also I don't see any errors in the logs. It looks like some kind of infinite loops. Tried restarting logstash but no help.