Logstash talking to rubygems.org during running?

Elastic Stack Logstash
1

Is there a scenario under which AFTER the configuration files have been checked and plugins are downloaded, logstash would try to talk to rubygems.org?

I have logstash version logstash 2.1.0. I have checked the configuration files with --configtest option and it checks out okay ..

/opt/logstash/bin/logstash --configtest -f logstash
DEBUG: exec /opt/logstash/vendor/jruby/bin/jruby --1.9 -J-XX:+UseParNewGC -J-XX:+UseConcMarkSweepGC -J-Djava.awt.headless=true -J-XX:CMSInitiatingOccupancyFraction=75 -J-XX:+UseCMSInitiatingOccupancyOnly -J-XX:+HeapDumpOnOutOfMemoryError -J-XX:HeapDumpPath=/opt/logstash/heapdump.hprof -J-Xmx1g /opt/logstash/lib/bootstrap/environment.rb logstash/runner.rb agent --configtest -f logstash
Configuration OK

However once logstash is started, it exits saying this

DEBUG: exec /opt/logstash/vendor/jruby/bin/jruby --1.9 -J-XX:+UseParNewGC -J-XX:+UseConcMarkSweepGC -J-Djava.awt.headless=true -J-XX:CMSInitiatingOccupancyFraction=75 -J-XX:+UseCMSInitiatingOccupancyOnly -J-XX:+HeapDumpOnOutOfMemoryError -J-XX:HeapDumpPath=/opt/logstash/heapdump.hprof -J-Xmx1g /opt/logstash/lib/bootstrap/environment.rb logstash/runner.rb agent -f /opt/logstash
The error reported is:
  initialize: name or service not known

The plugins that I am using in the configuration are installed (as verified by plugin list) - In case it helps, I am using logstash-input-sqs, logstash-output-sns, logstash-output-tcp, logstash-filter-mutate. They are all installed

I understand the error "initialize: name or service not known" has to do with connectivity from my docker container to rubygems.org. That's cool - except if all the preconditions above are satisfied, it should NOT talk to rubygems.

Is there a dependency that is obvious and I am missing it?

Thanks for any new ideas on what to look at.

Edit: I just verified, connectivity to rubygems.org is broken (my entire docker container is having connectivity issues). I fully intend to fix the underlying problem of connectivity - but curious to understand why logstash would be trying to talk to rubygems.org during running...

2

How do you know it's rubygems, did you do any packet sniffing to see or is it just a guess?

I'd suggest that it's probably something in your config that cannot resolve the network address in there.

3

Brilliant thinking! It was a guess. It was one of the other things in my configuration - which happened to have hosts for ES, some TCP hosts, and a bunch of other things. The problem was network connectivity, it just was NOT to rubygems.org ..

@Mark - thanks! Appreciate your suggestion, which helped me trace the problem!