Class: LogStash::Inputs::Kafka

Inherits:
Base
  • Object
show all
Includes:
PluginMixins::DeprecationLoggerSupport, PluginMixins::Kafka::AvroSchemaRegistry, PluginMixins::Kafka::Common
Defined in:
lib/logstash/inputs/kafka.rb

Overview

This input will read events from a Kafka topic. It uses the 0.10 version of the consumer API provided by Kafka to read messages from the broker.

Here’s a compatibility matrix that shows the Kafka client versions that are compatible with each combination of Logstash and the Kafka input plugin:

options=“header”

|========================================================== |Kafka Client Version |Logstash Version |Plugin Version |Why? |0.8 |2.0.0 - 2.x.x |<3.0.0 |Legacy, 0.8 is still popular |0.9 |2.0.0 - 2.3.x | 3.x.x |Works with the old Ruby Event API (‘event[’price’] = 10`)

|0.9 |2.4.x - 5.x.x | 4.x.x |Works with the new getter/setter APIs (‘event.set(’[price]‘, 10)`) |0.10.0.x |2.4.x - 5.x.x | 5.x.x |Not compatible with the <= 0.9 broker |0.10.1.x |2.4.x - 5.x.x | 6.x.x | |==========================================================

NOTE: We recommended that you use matching Kafka client and broker versions. During upgrades, you should upgrade brokers before clients because brokers target backwards compatibility. For example, the 0.9 broker is compatible with both the 0.8 consumer and 0.9 consumer APIs, but not the other way around.

This input supports connecting to Kafka over:

  • SSL (requires plugin version 3.0.0 or later)

  • Kerberos SASL (requires plugin version 5.1.0 or later)

By default security is disabled but can be turned on as needed.

The Logstash Kafka consumer handles group management and uses the default offset management strategy using Kafka topics.

Logstash instances by default form a single logical group to subscribe to Kafka topics Each Logstash Kafka consumer can run multiple threads to increase read throughput. Alternatively, you could run multiple Logstash instances with the same ‘group_id` to spread the load across physical machines. Messages in a topic will be distributed to all Logstash instances with the same `group_id`.

Ideally you should have as many threads as the number of partitions for a perfect balance – more threads than partitions means that some threads will be idle

For more information see kafka.apache.org/documentation.html#theconsumer

Kafka consumer configuration: kafka.apache.org/documentation.html#consumerconfigs

Constant Summary collapse

DEFAULT_DESERIALIZER_CLASS = 
"org.apache.kafka.common.serialization.StringDeserializer"
METADATA_NONE = 
Set[].freeze
METADATA_BASIC = 
Set[:record_props].freeze
METADATA_EXTENDED = 
Set[:record_props, :headers].freeze
METADATA_DEPRECATION_MAP = 
{ 'true' => 'basic', 'false' => 'none' }

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from PluginMixins::Kafka::AvroSchemaRegistry

#check_schema_registry_parameters, included, #schema_registry_validation?, #setup_schema_registry_config, #using_kerberos?

Methods included from PluginMixins::Kafka::Common

included, #reassign_dns_lookup, #set_sasl_config, #set_trustore_keystore_config

Constructor Details

#based(onschemaregistrychangethecodecdefault) ⇒ Kafka

Returns a new instance of Kafka.



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# File 'lib/logstash/inputs/kafka.rb', line 276

def initialize(params = {})
  unless params.key?('codec')
    params['codec'] = params.key?('schema_registry_url') ? 'json' : 'plain'
  end

  super(params)
end

Instance Attribute Details

#metadata_mode ⇒ Object (readonly)

Returns the value of attribute metadata_mode.



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# File 'lib/logstash/inputs/kafka.rb', line 273

def metadata_mode
  @metadata_mode
end

Instance Method Details

#do_poll(consumer) ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 361

def do_poll(consumer)
  records = []
  begin
    records = consumer.poll(java.time.Duration.ofMillis(poll_timeout_ms))
  rescue org.apache.kafka.common.errors.WakeupException => e
    logger.debug("Wake up from poll", :kafka_error_message => e)
    raise e unless stop?
  rescue org.apache.kafka.common.errors.FencedInstanceIdException => e
    logger.error("Another consumer with same group.instance.id has connected", :original_error_message => e.message)
    raise e unless stop?
  rescue => e
    logger.error("Unable to poll Kafka consumer",
                 :kafka_error_message => e,
                 :cause => e.respond_to?(:getCause) ? e.getCause : nil)
    Stud.stoppable_sleep(1) { stop? }
  end
  records
end

#handle_record(record, codec_instance, queue) ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 380

def handle_record(record, codec_instance, queue)
  # use + since .to_s on nil/boolean returns a frozen string since ruby 2.7
  codec_instance.decode(+record.value.to_s) do |event|
    decorate(event)
    maybe_set_metadata(event, record)
    queue << event
  end
end

#kafka_consumers ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 334

def kafka_consumers
  @runner_consumers
end

#maybe_commit_offset(consumer) ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 411

def maybe_commit_offset(consumer)
  begin
    consumer.commitSync if @enable_auto_commit.eql?(false)
  rescue org.apache.kafka.common.errors.WakeupException => e
    logger.debug("Wake up from commitSync", :kafka_error_message => e)
    raise e unless stop?
  rescue StandardError => e
    # For transient errors, the commit should be successful after the next set of
    # polled records has been processed.
    # But, it might also be worth thinking about adding a configurable retry mechanism
    logger.error("Unable to commit records",
                 :kafka_error_message => e,
                 :cause => e.respond_to?(:getCause) ? e.getCause() : nil)
  end
end

#maybe_set_metadata(event, record) ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 389

def maybe_set_metadata(event, record)
  if @metadata_mode.include?(:record_props)
    event.set("[@metadata][kafka][topic]", record.topic)
    event.set("[@metadata][kafka][consumer_group]", @group_id)
    event.set("[@metadata][kafka][partition]", record.partition)
    event.set("[@metadata][kafka][offset]", record.offset)
    event.set("[@metadata][kafka][key]", record.key)
    event.set("[@metadata][kafka][timestamp]", record.timestamp)
  end
  if @metadata_mode.include?(:headers)
    record.headers
          .select{|h| header_with_value(h) }
          .each do |header|
      s = String.from_java_bytes(header.value)
      s.force_encoding(Encoding::UTF_8)
      if s.valid_encoding?
        event.set("[@metadata][kafka][headers][" + header.key + "]", s)
      end
    end
  end
end

#register ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 285

def register
  @runner_threads = []
  @metadata_mode = extract_metadata_level(@decorate_events)
  reassign_dns_lookup
  @pattern ||= java.util.regex.Pattern.compile(@topics_pattern) unless @topics_pattern.nil?
  check_schema_registry_parameters
end

#run(logstash_queue) ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 316

def run(logstash_queue)
  @runner_consumers = consumer_threads.times.map do |i|
    thread_group_instance_id = consumer_threads > 1 && group_instance_id ? "#{group_instance_id}-#{i}" : group_instance_id
    subscribe(create_consumer("#{client_id}-#{i}", thread_group_instance_id))
  end
  @runner_threads = @runner_consumers.map.with_index { |consumer, i| thread_runner(logstash_queue, consumer,
                                                                                   "kafka-input-worker-#{client_id}-#{i}") }
  @runner_threads.each(&:start)
  @runner_threads.each(&:join)
end

#stop ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 328

def stop
  # if we have consumers, wake them up to unblock our runner threads
  @runner_consumers && @runner_consumers.each(&:wakeup)
end

#subscribe(consumer) ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 338

def subscribe(consumer)
  @pattern.nil? ? consumer.subscribe(topics) : consumer.subscribe(@pattern)
  consumer
end

#thread_runner(logstash_queue, consumer, name) ⇒ Object 



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# File 'lib/logstash/inputs/kafka.rb', line 343

def thread_runner(logstash_queue, consumer, name)
  java.lang.Thread.new do
    LogStash::Util::set_thread_name(name)
    begin
      codec_instance = @codec.clone
      until stop?
        records = do_poll(consumer)
        unless records.empty?
          records.each { |record| handle_record(record, codec_instance, logstash_queue) }
          maybe_commit_offset(consumer)
        end
      end
    ensure
      consumer.close
    end
  end
end