Logstash does not start main pipeline and produces no output on Ubuntu 16.04

[esbenp (Esben Petersen)]

I have installed Logstash and Elasticsearch on an Ubuntu 16.04 machine with 4 gb ram using apt-get install logstash.

When I boot the service with systemctl start logstash it does start the process (I can see it using ps aux | grep logstash) but no index is created in Elasticsearch. I thought I would try to debug it by just running the process in the terminal but when I do it creates no output.

This is the command I run:

sudo -u logstash /usr/share/logstash/bin/logstash \
 --path.settings /etc/logstash \
 -f /etc/logstash/conf.d/std.conf \
 --config.test_and_exit \
 --log.level debug

Nothing ever happens - it produces no output. It does not tell me that the main pipeline has started or gives me an error or anything.

I have checked /var/log/logstash put the folder is empty. I have checked syslog but there are only a few entries from when it was running as a service (only entries like Mar 22 20:11:21 elasticsearch-logstash systemd[1]: Started logstash.)

I installed logstash as root and I have tried chown -R logstash:adm both /usr/share/logstash/, var/log/logstash and /etc/logstash but nothing works.

I only have a single configuration file /etc/logstash/conf.d/main.conf and I have tried several pipeline configurations but same result:

main.conf (version 1)

input { 
  stdin {

  } 
} 
output {
  stdout {
    
  } 
}

main.conf (version 2)

input {
  stdin {
  }
}
output {
 file {
   path => "/var/log/logstash/yo.log"
 }
}

main.conf (version 3)

input { 
  stdin {

  } 
} 
output {
  stdout { codec => rubydebug }
}

None of these configurations change the outcome in anyway. I have no idea why it is silently failing on me.

It should be noted that I have also tried installing by downloading the tar file and running Logstash from the downloaded directory with same result.

Any ideas?

[warkolm (Mark Walkom)]

Its likely waiting for input into stdin, have you tried passing something in?

[dfinn (Daniel J Finn)]

It also doesn't look like you've told it to output to Elasticsearch. I don't think it does this by default but maybe I'm wrong.

Here's my output section:

output {
  elasticsearch {
    hosts => "localhost:9200"
  }
  stdout { codec => rubydebug }
}

[esbenp (Esben Petersen)]

Turns out it was the lack of entropy problem.

The issue: https://github.com/elastic/logstash/issues/5491
The solution: https://www.digitalocean.com/community/tutorials/how-to-setup-additional-entropy-for-cloud-servers-using-haveged