{:timestamp=>"2015-03-02T14:44:18.801000+0200", :message=>"Exception in filterworker", "exception"=>#<NoMethodError: undefined method `[]' for nil:NilClass>, "backtrace"=>["(ruby filter code):1:in `register'", "org/jruby/RubyProc.java:271:in `call'", "/opt/logstash/lib/logstash/filters/ruby.rb:38:in `filter'", "(eval):77:in `initialize'", "org/jruby/RubyProc.java:271:in `call'", "/opt/logstash/lib/logstash/pipeline.rb:262:in `filter'", "/opt/logstash/lib/logstash/pipeline.rb:203:in `filterworker'", "/opt/logstash/lib/logstash/pipeline.rb:143:in `start_filters'"], :level=>:error}