Class: Kafka::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/kafka/client.rb

Instance Method Summary collapse

Constructor Details

#initialize(seed_brokers:, client_id: "ruby-kafka", logger: nil, connect_timeout: nil, socket_timeout: nil, ssl_ca_cert_file_path: nil, ssl_ca_cert: nil, ssl_client_cert: nil, ssl_client_cert_key: nil, ssl_client_cert_key_password: nil, ssl_client_cert_chain: nil, sasl_gssapi_principal: nil, sasl_gssapi_keytab: nil, sasl_plain_authzid: '', sasl_plain_username: nil, sasl_plain_password: nil, sasl_scram_username: nil, sasl_scram_password: nil, sasl_scram_mechanism: nil, sasl_over_ssl: true, ssl_ca_certs_from_system: false, sasl_oauth_token_provider: nil, ssl_verify_hostname: true) ⇒ Client

Initializes a new Kafka client.



69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
 
# File 'lib/kafka/client.rb', line 69

def initialize(seed_brokers:, client_id: "ruby-kafka", logger: nil, connect_timeout: nil, socket_timeout: nil,
               ssl_ca_cert_file_path: nil, ssl_ca_cert: nil, ssl_client_cert: nil, ssl_client_cert_key: nil,
               ssl_client_cert_key_password: nil, ssl_client_cert_chain: nil, sasl_gssapi_principal: nil,
               sasl_gssapi_keytab: nil, sasl_plain_authzid: '', sasl_plain_username: nil, sasl_plain_password: nil,
               sasl_scram_username: nil, sasl_scram_password: nil, sasl_scram_mechanism: nil,
               sasl_over_ssl: true, ssl_ca_certs_from_system: false, sasl_oauth_token_provider: nil, ssl_verify_hostname: true)
  @logger = TaggedLogger.new(logger)
  @instrumenter = Instrumenter.new(client_id: client_id)
  @seed_brokers = normalize_seed_brokers(seed_brokers)

  ssl_context = SslContext.build(
    ca_cert_file_path: ssl_ca_cert_file_path,
    ca_cert: ssl_ca_cert,
    client_cert: ssl_client_cert,
    client_cert_key: ssl_client_cert_key,
    client_cert_key_password: ssl_client_cert_key_password,
    client_cert_chain: ssl_client_cert_chain,
    ca_certs_from_system: ssl_ca_certs_from_system,
    verify_hostname: ssl_verify_hostname
  )

  sasl_authenticator = SaslAuthenticator.new(
    sasl_gssapi_principal: sasl_gssapi_principal,
    sasl_gssapi_keytab: sasl_gssapi_keytab,
    sasl_plain_authzid: sasl_plain_authzid,
    sasl_plain_username: sasl_plain_username,
    sasl_plain_password: sasl_plain_password,
    sasl_scram_username: sasl_scram_username,
    sasl_scram_password: sasl_scram_password,
    sasl_scram_mechanism: sasl_scram_mechanism,
    sasl_oauth_token_provider: sasl_oauth_token_provider,
    logger: @logger
  )

  if sasl_authenticator.enabled? && sasl_over_ssl && ssl_context.nil?
    raise ArgumentError, "SASL authentication requires that SSL is configured"
  end

  @connection_builder = ConnectionBuilder.new(
    client_id: client_id,
    connect_timeout: connect_timeout,
    socket_timeout: socket_timeout,
    ssl_context: ssl_context,
    logger: @logger,
    instrumenter: @instrumenter,
    sasl_authenticator: sasl_authenticator
  )

  @cluster = initialize_cluster
end

Instance Method Details

#alter_configs(broker_id, configs = []) ⇒ nil

Alter broker configs



552
553
554
 
# File 'lib/kafka/client.rb', line 552

def alter_configs(broker_id, configs = [])
  @cluster.alter_configs(broker_id, configs)
end

#alter_topic(name, configs = {}) ⇒ nil

Note:

This is an alpha level API and is subject to change.

Alter the configuration of a topic.

Configuration keys must match Kafka's topic-level configs.

Examples:

Describing the cleanup policy config of a topic

kafka = Kafka.new(["kafka1:9092"])
kafka.alter_topic("my-topic", "cleanup.policy" => "delete", "max.message.byte" => "100000")



629
630
631
 
# File 'lib/kafka/client.rb', line 629

def alter_topic(name, configs = {})
  @cluster.alter_topic(name, configs)
end

#apis ⇒ Object 



738
739
740
 
# File 'lib/kafka/client.rb', line 738

def apis
  @cluster.apis
end

#async_producer(delivery_interval: 0, delivery_threshold: 0, max_queue_size: 1000, max_retries: -1,, retry_backoff: 0, **options) ⇒ AsyncProducer

Creates a new AsyncProducer instance.

All parameters allowed by #producer can be passed. In addition to this, a few extra parameters can be passed when creating an async producer.

See Also:



307
308
309
310
311
312
313
314
315
316
317
318
319
320
 
# File 'lib/kafka/client.rb', line 307

def async_producer(delivery_interval: 0, delivery_threshold: 0, max_queue_size: 1000, max_retries: -1, retry_backoff: 0, **options)
  sync_producer = producer(**options)

  AsyncProducer.new(
    sync_producer: sync_producer,
    delivery_interval: delivery_interval,
    delivery_threshold: delivery_threshold,
    max_queue_size: max_queue_size,
    max_retries: max_retries,
    retry_backoff: retry_backoff,
    instrumenter: @instrumenter,
    logger: @logger,
  )
end

#brokers ⇒ Array<Kafka::BrokerInfo>

List all brokers in the cluster.



745
746
747
 
# File 'lib/kafka/client.rb', line 745

def brokers
  @cluster.cluster_info.brokers
end

#close ⇒ nil

Closes all connections to the Kafka brokers and frees up used resources.



759
760
761
 
# File 'lib/kafka/client.rb', line 759

def close
  @cluster.disconnect
end

#consumer(group_id:, session_timeout: 30, rebalance_timeout: 60, offset_commit_interval: 10, offset_commit_threshold: 0, heartbeat_interval: 10, offset_retention_time: nil, fetcher_max_queue_size: 100) ⇒ Consumer

Creates a new Kafka consumer.



340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
 
# File 'lib/kafka/client.rb', line 340

def consumer(
    group_id:,
    session_timeout: 30,
    rebalance_timeout: 60,
    offset_commit_interval: 10,
    offset_commit_threshold: 0,
    heartbeat_interval: 10,
    offset_retention_time: nil,
    fetcher_max_queue_size: 100
)
  cluster = initialize_cluster

  instrumenter = DecoratingInstrumenter.new(@instrumenter, {
    group_id: group_id,
  })

  # The Kafka protocol expects the retention time to be in ms.
  retention_time = (offset_retention_time && offset_retention_time * 1_000) || -1

  group = ConsumerGroup.new(
    cluster: cluster,
    logger: @logger,
    group_id: group_id,
    session_timeout: session_timeout,
    rebalance_timeout: rebalance_timeout,
    retention_time: retention_time,
    instrumenter: instrumenter,
  )

  fetcher = Fetcher.new(
    cluster: initialize_cluster,
    group: group,
    logger: @logger,
    instrumenter: instrumenter,
    max_queue_size: fetcher_max_queue_size
  )

  offset_manager = OffsetManager.new(
    cluster: cluster,
    group: group,
    fetcher: fetcher,
    logger: @logger,
    commit_interval: offset_commit_interval,
    commit_threshold: offset_commit_threshold,
    offset_retention_time: offset_retention_time
  )

  heartbeat = Heartbeat.new(
    group: group,
    interval: heartbeat_interval,
    instrumenter: instrumenter
  )

  Consumer.new(
    cluster: cluster,
    logger: @logger,
    instrumenter: instrumenter,
    group: group,
    offset_manager: offset_manager,
    fetcher: fetcher,
    session_timeout: session_timeout,
    heartbeat: heartbeat,
  )
end

#controller_broker ⇒ Kafka::BrokerInfo

The current controller broker in the cluster.



752
753
754
 
# File 'lib/kafka/client.rb', line 752

def controller_broker
  brokers.find {|broker| broker.node_id == @cluster.cluster_info.controller_id }
end

#create_partitions_for(name, num_partitions: 1, timeout: 30) ⇒ nil

Create partitions for a topic.

the topic partitions to be added.



657
658
659
 
# File 'lib/kafka/client.rb', line 657

def create_partitions_for(name, num_partitions: 1, timeout: 30)
  @cluster.create_partitions_for(name, num_partitions: num_partitions, timeout: timeout)
end

#create_topic(name, num_partitions: 1, replication_factor: 1, timeout: 30, config: {}) ⇒ nil

Creates a topic in the cluster.

Examples:

Creating a topic with log compaction

# Enable log compaction:
config = { "cleanup.policy" => "compact" }

# Create the topic:
kafka.create_topic("dns-mappings", config: config)

Raises:



576
577
578
579
580
581
582
583
584
 
# File 'lib/kafka/client.rb', line 576

def create_topic(name, num_partitions: 1, replication_factor: 1, timeout: 30, config: {})
  @cluster.create_topic(
    name,
    num_partitions: num_partitions,
    replication_factor: replication_factor,
    timeout: timeout,
    config: config,
  )
end

#delete_topic(name, timeout: 30) ⇒ nil

Delete a topic in the cluster.



592
593
594
 
# File 'lib/kafka/client.rb', line 592

def delete_topic(name, timeout: 30)
  @cluster.delete_topic(name, timeout: timeout)
end

#deliver_message(value, key: nil, headers: {}, topic:, partition: nil, partition_key: nil, retries: 1) ⇒ nil

Delivers a single message to the Kafka cluster.

Note: Only use this API for low-throughput scenarios. If you want to deliver many messages at a high rate, or if you want to configure the way messages are sent, use the #producer or #async_producer APIs instead.



138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
 
# File 'lib/kafka/client.rb', line 138

def deliver_message(value, key: nil, headers: {}, topic:, partition: nil, partition_key: nil, retries: 1)
  create_time = Time.now

  # We want to fail fast if `topic` isn't a String
  topic = topic.to_str

  message = PendingMessage.new(
    value: value,
    key: key,
    headers: headers,
    topic: topic,
    partition: partition,
    partition_key: partition_key,
    create_time: create_time
  )

  if partition.nil?
    partition_count = @cluster.partitions_for(topic).count
    partition = Partitioner.partition_for_key(partition_count, message)
  end

  buffer = MessageBuffer.new

  buffer.write(
    value: message.value,
    key: message.key,
    headers: message.headers,
    topic: message.topic,
    partition: partition,
    create_time: message.create_time,
  )

  @cluster.add_target_topics([topic])

  compressor = Compressor.new(
    instrumenter: @instrumenter,
  )

  transaction_manager = TransactionManager.new(
    cluster: @cluster,
    logger: @logger,
    idempotent: false,
    transactional: false
  )

  operation = ProduceOperation.new(
    cluster: @cluster,
    transaction_manager: transaction_manager,
    buffer: buffer,
    required_acks: 1,
    ack_timeout: 10,
    compressor: compressor,
    logger: @logger,
    instrumenter: @instrumenter,
  )

  attempt = 1

  begin
    operation.execute

    unless buffer.empty?
      raise DeliveryFailed.new(nil, [message])
    end
  rescue Kafka::Error => e
    @cluster.mark_as_stale!

    if attempt >= (retries + 1)
      raise
    else
      attempt += 1
      @logger.warn "Error while delivering message, #{e.class}: #{e.message}; retrying after 1s..."

      sleep 1

      retry
    end
  end
end

#describe_configs(broker_id, configs = []) ⇒ Array<Kafka::Protocol::DescribeConfigsResponse::ConfigEntry>

Describe broker configs



543
544
545
 
# File 'lib/kafka/client.rb', line 543

def describe_configs(broker_id, configs = [])
  @cluster.describe_configs(broker_id, configs)
end

#describe_group(group_id) ⇒ Kafka::Protocol::DescribeGroupsResponse::Group

Describe a consumer group



637
638
639
 
# File 'lib/kafka/client.rb', line 637

def describe_group(group_id)
  @cluster.describe_group(group_id)
end

#describe_topic(name, configs = []) ⇒ Hash<String, String>

Note:

This is an alpha level API and is subject to change.

Describe the configuration of a topic.

Retrieves the topic configuration from the Kafka brokers. Configuration names refer to Kafka's topic-level configs.

Examples:

Describing the cleanup policy config of a topic

kafka = Kafka.new(["kafka1:9092"])
kafka.describe_topic("my-topic", ["cleanup.policy"])
#=> { "cleanup.policy" => "delete" }



611
612
613
 
# File 'lib/kafka/client.rb', line 611

def describe_topic(name, configs = [])
  @cluster.describe_topic(name, configs)
end

#each_message(topic:, start_from_beginning: true, max_wait_time: 5, min_bytes: 1, max_bytes: 1048576, &block) ⇒ nil

Enumerate all messages in a topic.



512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
 
# File 'lib/kafka/client.rb', line 512

def each_message(topic:, start_from_beginning: true, max_wait_time: 5, min_bytes: 1, max_bytes: 1048576, &block)
  default_offset ||= start_from_beginning ? :earliest : :latest
  offsets = Hash.new { default_offset }

  loop do
    operation = FetchOperation.new(
      cluster: @cluster,
      logger: @logger,
      min_bytes: min_bytes,
      max_wait_time: max_wait_time,
    )

    @cluster.partitions_for(topic).map(&:partition_id).each do |partition|
      partition_offset = offsets[partition]
      operation.fetch_from_partition(topic, partition, offset: partition_offset, max_bytes: max_bytes)
    end

    batches = operation.execute

    batches.each do |batch|
      batch.messages.each(&block)
      offsets[batch.partition] = batch.last_offset + 1 unless batch.unknown_last_offset?
    end
  end
end

#fetch_group_offsets(group_id) ⇒ Hash<String, Hash<Integer, Kafka::Protocol::OffsetFetchResponse::PartitionOffsetInfo>>

Fetch all committed offsets for a consumer group



645
646
647
 
# File 'lib/kafka/client.rb', line 645

def fetch_group_offsets(group_id)
  @cluster.fetch_group_offsets(group_id)
end

#fetch_messages(topic:, partition:, offset: :latest, max_wait_time: 5, min_bytes: 1, max_bytes: 1048576, retries: 1) ⇒ Array<Kafka::FetchedMessage>

Fetches a batch of messages from a single partition. Note that it's possible to get back empty batches.

The starting point for the fetch can be configured with the :offset argument. If you pass a number, the fetch will start at that offset. However, there are two special Symbol values that can be passed instead:

  • :earliest — the first offset in the partition.
  • :latest — the next offset that will be written to, effectively making the call block until there is a new message in the partition.

The Kafka protocol specifies the numeric values of these two options: -2 and -1, respectively. You can also pass in these numbers directly.

Example

When enumerating the messages in a partition, you typically fetch batches sequentially.

offset = :earliest

loop do
  messages = kafka.fetch_messages(
    topic: "my-topic",
    partition: 42,
    offset: offset,
  )

  messages.each do |message|
    puts message.offset, message.key, message.value

    # Set the next offset that should be read to be the subsequent
    # offset.
    offset = message.offset + 1
  end
end

See a working example in examples/simple-consumer.rb.



464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
 
# File 'lib/kafka/client.rb', line 464

def fetch_messages(topic:, partition:, offset: :latest, max_wait_time: 5, min_bytes: 1, max_bytes: 1048576, retries: 1)
  operation = FetchOperation.new(
    cluster: @cluster,
    logger: @logger,
    min_bytes: min_bytes,
    max_bytes: max_bytes,
    max_wait_time: max_wait_time,
  )

  operation.fetch_from_partition(topic, partition, offset: offset, max_bytes: max_bytes)

  attempt = 1

  begin
    operation.execute.flat_map {|batch| batch.messages }
  rescue Kafka::Error => e
    @cluster.mark_as_stale!

    if attempt >= (retries + 1)
      raise
    else
      attempt += 1
      @logger.warn "Error while fetching messages, #{e.class}: #{e.message}; retrying..."
      retry
    end
  end
end

#groups ⇒ Array<String>

Lists all consumer groups in the cluster



679
680
681
 
# File 'lib/kafka/client.rb', line 679

def groups
  @cluster.list_groups
end

#has_topic?(topic) ⇒ Boolean 



683
684
685
686
687
 
# File 'lib/kafka/client.rb', line 683

def has_topic?(topic)
  @cluster.clear_target_topics
  @cluster.add_target_topics([topic])
  @cluster.topics.include?(topic)
end

#last_offset_for(topic, partition) ⇒ Integer

Retrieve the offset of the last message in a partition. If there are no messages in the partition -1 is returned.



704
705
706
707
708
 
# File 'lib/kafka/client.rb', line 704

def last_offset_for(topic, partition)
  # The offset resolution API will return the offset of the "next" message to
  # be written when resolving the "latest" offset, so we subtract one.
  @cluster.resolve_offset(topic, partition, :latest) - 1
end

#last_offsets_for(*topics) ⇒ Hash<String, Hash<Integer, Integer>>

Retrieve the offset of the last message in each partition of the specified topics.

Examples:

last_offsets_for('topic-1', 'topic-2') # =>
# {
#   'topic-1' => { 0 => 100, 1 => 100 },
#   'topic-2' => { 0 => 100, 1 => 100 }
# }



720
721
722
723
724
725
726
727
 
# File 'lib/kafka/client.rb', line 720

def last_offsets_for(*topics)
  @cluster.add_target_topics(topics)
  topics.map {|topic|
    partition_ids = @cluster.partitions_for(topic).collect(&:partition_id)
    partition_offsets = @cluster.resolve_offsets(topic, partition_ids, :latest)
    [topic, partition_offsets.collect { |k, v| [k, v - 1] }.to_h]
  }.to_h
end

#partitions_for(topic) ⇒ Integer

Counts the number of partitions in a topic.



693
694
695
 
# File 'lib/kafka/client.rb', line 693

def partitions_for(topic)
  @cluster.partitions_for(topic).count
end

#producer(compression_codec: nil, compression_threshold: 1, ack_timeout: 5, required_acks: :all, max_retries: 2, retry_backoff: 1, max_buffer_size: 1000, max_buffer_bytesize: 10_000_000, idempotent: false, transactional: false, transactional_id: nil, transactional_timeout: 60) ⇒ Kafka::Producer

Initializes a new Kafka producer.



248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
 
# File 'lib/kafka/client.rb', line 248

def producer(
  compression_codec: nil,
  compression_threshold: 1,
  ack_timeout: 5,
  required_acks: :all,
  max_retries: 2,
  retry_backoff: 1,
  max_buffer_size: 1000,
  max_buffer_bytesize: 10_000_000,
  idempotent: false,
  transactional: false,
  transactional_id: nil,
  transactional_timeout: 60
)
  cluster = initialize_cluster
  compressor = Compressor.new(
    codec_name: compression_codec,
    threshold: compression_threshold,
    instrumenter: @instrumenter,
  )

  transaction_manager = TransactionManager.new(
    cluster: cluster,
    logger: @logger,
    idempotent: idempotent,
    transactional: transactional,
    transactional_id: transactional_id,
    transactional_timeout: transactional_timeout,
  )

  Producer.new(
    cluster: cluster,
    transaction_manager: transaction_manager,
    logger: @logger,
    instrumenter: @instrumenter,
    compressor: compressor,
    ack_timeout: ack_timeout,
    required_acks: required_acks,
    max_retries: max_retries,
    retry_backoff: retry_backoff,
    max_buffer_size: max_buffer_size,
    max_buffer_bytesize: max_buffer_bytesize,
  )
end

#supports_api?(api_key, version = nil) ⇒ Boolean

Check whether current cluster supports a specific version or not



734
735
736
 
# File 'lib/kafka/client.rb', line 734

def supports_api?(api_key, version = nil)
  @cluster.supports_api?(api_key, version)
end

#topics ⇒ Array<String>

Lists all topics in the cluster.



664
665
666
667
668
669
670
671
672
673
674
 
# File 'lib/kafka/client.rb', line 664

def topics
  attempts = 0
  begin
    attempts += 1
    @cluster.list_topics
  rescue Kafka::ConnectionError
    @cluster.mark_as_stale!
    retry unless attempts > 1
    raise
  end
end