Logstash can’t find JRuby

So I suppose this can be an answer now. Looks like your tests were run as root user. and your service is running as logstash. Your logs from tests do not show any errors. But I think your problem is with file permissions. Please check that config files are readable for user logstash and log files are writable for him. Plus, since that process should be able to read apache log files directly, check if logstash is to read them as well. If logstash is configured to listen for incoming network connections, check of ports configured are higher than 1024.

Also you can try running your tests as logstash user:

something like that:

su -c "/path/to/logstash -t -f /path/to/config" logstash

Logstash is one of those things that just doesn't quite live where you expect it to live, and the documentation is reallllly light (read: non-existent) on where they expect you to find things, so if you've installed it from a package then it can be nigh impossible to find the expected location documented. ¹

Logstash typically lives in /opt/logstash and you can find the logstash binary in the bin folder (/opt/logstash/bin).

From there you can run -V or --version

./logstash -v

or

./logstash --version

From your comments on another answer, it would appear that this is in a docker container. This is the sort of thing you should really be including in your original question.

You will want to make use of docker exec. You will need to use docker ps to list your containers, and pass that through to your docker exec command.

For example:

docker exec -d elk_container /opt/logstash/bin/logstash --version

_{¹I don't want this to be misconstrued. Logstash documentation is excellent - it's just the parts about where all the different bits are expected to live that's impossible to find}