Logstash service started but not working, command line is working

when i run logstash in command line all is working but not as a service
i get no data
no logs
conf is ok
ps shows:
logstash 10120 1 1 08:44 pts/0 00:00:00 /usr/bin/java -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -Djava.awt.headless=true -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -Djava.io.tmpdir=/var/lib/logstash -Xmx500m -Xss2048k -Djffi.boot.library.path=/opt/logstash/vendor/jruby/lib/jni -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -Djava.awt.headless=true -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -Djava.io.tmpdir=/var/lib/logstash -Xbootclasspath/a:/opt/logstash/vendor/jruby/lib/jruby.jar -classpath : -Djruby.home=/opt/logstash/vendor/jruby -Djruby.lib=/opt/logstash/vendor/jruby/lib -Djruby.script=jruby -Djruby.shell=/bin/sh org.jruby.Main --1.9 /opt/logstash/lib/bootstrap/environment.rb logstash/runner.rb agent -f /etc/logstash/conf.d -l /var/log/logstash/logstash.log

Try increasing the logging verbosity by starting Logstash with --verbose or even --debug. One possible cause could be that the logstash user doesn't have read permission to the log files.

i see the permissions on var/log/logstash is
drwxrwxr-x 2 logstash root 4096 Oct 27 18:48 logstash

and after starting the service
-rw-r--r-- 1 root root 0 Apr 19 09:07 logstash.err
-rw-r--r-- 1 root root 0 Apr 19 09:07 logstash.stdout

why its root?

Why indeed? This should be changed. How did you install Logstash?

yum install logstash

repo file:
name=logstash repository for 2.x packages