I'm using logstash(5.6.0) to read .gz file(has a list of .dat files) by using gzip_lines codec. It appears the compressed file is not being read but I do not see any errors in the logstash logs and indexes in ElasticSearch. I have verified that the plugin is installed.
path => ["/opt/data/appl1/*.gz"]
type => "appl-test"
start_position => "beginning"
sincedb_path => "/dev/null"
codec => "gzip_lines"