The following is a logstash filter conf for zeromq

logstash.conf

input {
  stdin {
  }
}

filter {
  zeromq {
    address => "tcp://127.0.0.1:8080"
    mode => "client"
  }
}

## zeromq filter plugin
filter {
   ## If the zeromq tag is present then added a type as matched 
   ## this is just and example obviously one can add the type tag in ruby itself 
   ## over here https://gist.github.com/meetme2meat/352b1a33306d9a8f157f2d61cbd101f4#file-logstash-rb-L28.
   
   if ([zeromq]) {
     mutate {
        add_field => {
          "type" => "matched" 
	}
     }
   }
   ## if the zeromq tag is not present than add a type 'non_matched'
   else {
     mutate {
       add_field => {
          "type" => "not_matched" 
       }
   }
  }
}

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

## confirm the above logstash configuration

# logstash -f logstash.conf --configtest

## Load the logstash with the following configuration 
# logstash -f  logstash.conf

## Start the following ruby application on seperate terminal
## https://gist.github.com/meetme2meat/352b1a33306d9a8f157f2d61cbd101f4

# ruby logstash.rb

## Note you need zeromq to be compiled and installed on your machine for this example to run successfully.