Logstash logrotation doesn't work properly

Elastic Stack Logstash
1

When attempting to do log rotation on logstash's logs I get weirdness due to the Null-bytes problem.
I am using the following logrotate config:

/var/log/logstash/*.err /var/log/logstash/*.log /var/log/logstash/*.stdout {
    copytruncate
    missingok
    rotate 5
    size 200K
    notifempty
    sharedscripts
    compress
    delaycompress
    nodateext
}

Seconds after log rotation happens, the new file size goes back up to the previous size.
I've tried restarting logstash in the postrotate script but for some reason this doesn't work.

Here is the relevant portion of my init.d script:

 nice -n ${LS_NICE} chroot --userspec $LS_USER:$LS_GROUP / sh -c "
    cd $LS_HOME
    ulimit -n ${LS_OPEN_FILES}
    exec \"$program\" $args
  " > "${LS_LOG_DIR}/$name.stdout" 2> "${LS_LOG_DIR}/$name.err" &

Is there a way to tell logstash to release its log files?

Note: This was only for testing with the debug output plugin to simulate rotations often.
Also, i'm running logstash in a docker container.

2

Any particular reason you're using copytruncate? I'd expect a rename to work better. Doesn't copytruncate require that the logging application understands that the file has shrunk?

Is there a way to tell logstash to release its log files?

Restarting it will definitely close the files.