Logstash with multiple kafka inputs

Question

I am trying to filter kafka events from multiple topics, but once all events from one topic has been filtered logstash is not able to fetch events from the other kafka topic. I am using topics with 3 partitions and 2 replications Here is my logstash config file

input {
    kafka{              
        auto_offset_reset => "smallest"
        consumer_id => "logstashConsumer1"          
        topic_id => "unprocessed_log1"
        zk_connect=>"192.42.79.67:2181,192.41.85.48:2181,192.10.13.14:2181"
        type => "kafka_type_1"
}
kafka{              
    auto_offset_reset => "smallest"
    consumer_id => "logstashConsumer1"          
    topic_id => "unprocessed_log2"
    zk_connect => "192.42.79.67:2181,192.41.85.48:2181,192.10.13.14:2181"
    type => "kafka_type_2"
}
}
filter{
    if [type] == "kafka_type_1"{
    csv { 
        separator=>" "
        source => "data"        
    }   
}
if [type] == "kafka_type_2"{    
    csv { 
        separator => " "        
        source => "data"
    }
}
}
output{
    stdout{ codec=>rubydebug{metadata => true }}
}

Answer 1

Its a very late reply but if you wanted to take input multiple topic and output to another kafka multiple output, you can do something like this :

input {
  kafka {
    topics => ["topic1", "topic2"]
    codec => "json"
    bootstrap_servers => "kafka-broker-1:9092,kafka-broker-2:9092,kafka-broker-3:9092"
    decorate_events => true
    group_id => "logstash-multi-topic-consumers"
    consumer_threads => 5
  }
}
    
output {
   if [kafka][topic] == "topic1" {
     kafka {
       codec => "json"
       topic_id => "new_topic1"
       bootstrap_servers => "output-kafka-1:9092"
     }
   }
   else if [kafka][topic] == "topic2" {
      kafka {
       codec => "json"
       topic_id => "new_topic2"
       bootstrap_servers => "output-kafka-1:9092"
      }
    }
}

Be careful while detailing your bootstrap servers, give name on which your kafka has advertised listeners.

Ref-1: https://www.elastic.co/guide/en/logstash/current/plugins-inputs-kafka.html#plugins-inputs-kafka-group_id

Ref-2: https://www.elastic.co/guide/en/logstash/current/plugins-inputs-kafka.html#plugins-inputs-kafka-decorate_events

Answer 2

The previous answer didn't work for me and it seems it doses not recognize conditional statements in output, Here is my answer which correct and valid at least for my case where I have defined tags in input for both Kafka consumers and documents (in my case they are logs) are ingested into separate indexes related to their consumer topics .

input {
  kafka {
        group_id => "35834"
        topics => ["First-Topic"]
        bootstrap_servers => "localhost:9092"
        codec => json
        tags => ["First-Topic"]
  }
    kafka {
        group_id => "35834"
        topics => ["Second-Topic"]
        bootstrap_servers => "localhost:9092"
        codec => json
        tags => ["Second-Topic"]
    }
}

filter {

}
output {
    if "Second-Topic" in [tags]{
     elasticsearch {
         hosts => ["localhost:9200"]
         document_type => "_doc"
         index => "logger"
     }
      stdout { codec => rubydebug
           }
   }
   else if "First-Topic" in [tags]{
    elasticsearch {
          hosts => ["localhost:9200"]
          document_type => "_doc"
          index => "saga"
      }
      stdout { codec => rubydebug
      }
    }
}