Class: Kafka::Client
- Inherits:
-
Object
- Object
- Kafka::Client
- Defined in:
- lib/kafka/client.rb
Constant Summary collapse
- URI_SCHEMES =
["kafka", "kafka+ssl"]
Instance Method Summary collapse
- #apis ⇒ Object
-
#async_producer(delivery_interval: 0, delivery_threshold: 0, max_queue_size: 1000, **options) ⇒ AsyncProducer
Creates a new AsyncProducer instance.
-
#close ⇒ nil
Closes all connections to the Kafka brokers and frees up used resources.
-
#consumer(group_id:, session_timeout: 30, offset_commit_interval: 10, offset_commit_threshold: 0, heartbeat_interval: 10, offset_retention_time: nil) ⇒ Consumer
Creates a new Kafka consumer.
- #create_topic(name, **options) ⇒ Object
-
#deliver_message(value, key: nil, topic:, partition: nil, partition_key: nil, retries: 1) ⇒ nil
Delivers a single message to the Kafka cluster.
-
#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.
-
#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.
- #has_topic?(topic) ⇒ Boolean
-
#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, 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) ⇒ Client
constructor
Initializes a new Kafka client.
-
#last_offset_for(topic, partition) ⇒ Integer
Retrieve the offset of the last message in a partition.
-
#last_offsets_for(*topics) ⇒ Hash<String, Hash<Integer, Integer>>
Retrieve the offset of the last message in each partition of the specified topics.
-
#partitions_for(topic) ⇒ Integer
Counts the number of partitions in a topic.
-
#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) ⇒ Kafka::Producer
Initializes a new Kafka producer.
-
#topics ⇒ Array<String>
Lists all topics in the cluster.
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, 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) ⇒ Client
Initializes a new Kafka client.
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# File 'lib/kafka/client.rb', line 59 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, 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) @logger = logger || Logger.new(nil) @instrumenter = Instrumenter.new(client_id: client_id) @seed_brokers = normalize_seed_brokers(seed_brokers) ssl_context = build_ssl_context(ssl_ca_cert_file_path, ssl_ca_cert, ssl_client_cert, ssl_client_cert_key) 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, logger: @logger ) @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
#apis ⇒ Object
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# File 'lib/kafka/client.rb', line 512 def apis @cluster.apis end |
#async_producer(delivery_interval: 0, delivery_threshold: 0, max_queue_size: 1000, **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.
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# File 'lib/kafka/client.rb', line 244 def async_producer(delivery_interval: 0, delivery_threshold: 0, max_queue_size: 1000, **) sync_producer = producer(**) AsyncProducer.new( sync_producer: sync_producer, delivery_interval: delivery_interval, delivery_threshold: delivery_threshold, max_queue_size: max_queue_size, instrumenter: @instrumenter, logger: @logger, ) end |
#close ⇒ nil
Closes all connections to the Kafka brokers and frees up used resources.
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# File 'lib/kafka/client.rb', line 519 def close @cluster.disconnect end |
#consumer(group_id:, session_timeout: 30, offset_commit_interval: 10, offset_commit_threshold: 0, heartbeat_interval: 10, offset_retention_time: nil) ⇒ Consumer
Creates a new Kafka consumer.
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# File 'lib/kafka/client.rb', line 272 def consumer(group_id:, session_timeout: 30, offset_commit_interval: 10, offset_commit_threshold: 0, heartbeat_interval: 10, offset_retention_time: nil) 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, retention_time: retention_time, instrumenter: instrumenter, ) offset_manager = OffsetManager.new( cluster: cluster, group: group, 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, ) Consumer.new( cluster: cluster, logger: @logger, instrumenter: instrumenter, group: group, offset_manager: offset_manager, session_timeout: session_timeout, heartbeat: heartbeat, ) end |
#create_topic(name, **options) ⇒ Object
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# File 'lib/kafka/client.rb', line 454 def create_topic(name, **) @cluster.create_topic(name, **) end |
#deliver_message(value, key: nil, 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.
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# File 'lib/kafka/client.rb', line 112 def (value, key: nil, topic:, partition: nil, partition_key: nil, retries: 1) create_time = Time.now = PendingMessage.new( value, key, topic, partition, partition_key, create_time, ) if partition.nil? partition_count = @cluster.partitions_for(topic).count partition = Partitioner.partition_for_key(partition_count, ) end buffer = MessageBuffer.new buffer.write( value: .value, key: .key, topic: .topic, partition: partition, create_time: .create_time, ) @cluster.add_target_topics([topic]) compressor = Compressor.new( instrumenter: @instrumenter, ) operation = ProduceOperation.new( cluster: @cluster, 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, []) 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.}; retrying after 1s..." sleep 1 retry end end 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.
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# File 'lib/kafka/client.rb', line 428 def (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..each(&block) offsets[batch.partition] = batch.last_offset + 1 end end end |
#fetch_messages(topic:, partition:, offset: :latest, max_wait_time: 5, min_bytes: 1, max_bytes: 1048576, retries: 1) ⇒ Array<Kafka::FetchedMessage>
This API is still alpha level. Don't try to use it in production.
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
= kafka.(
topic: "my-topic",
partition: 42,
offset: offset,
)
.each do ||
puts .offset, .key, .value
# Set the next offset that should be read to be the subsequent
# offset.
offset = .offset + 1
end
end
See a working example in examples/simple-consumer.rb
.
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# File 'lib/kafka/client.rb', line 377 def (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. } 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.}; retrying..." retry end end end |
#has_topic?(topic) ⇒ Boolean
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# File 'lib/kafka/client.rb', line 466 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.
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# File 'lib/kafka/client.rb', line 487 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.
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# File 'lib/kafka/client.rb', line 503 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.
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# File 'lib/kafka/client.rb', line 476 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) ⇒ Kafka::Producer
Initializes a new Kafka producer.
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# File 'lib/kafka/client.rb', line 209 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) compressor = Compressor.new( codec_name: compression_codec, threshold: compression_threshold, instrumenter: @instrumenter, ) Producer.new( cluster: initialize_cluster, 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 |
#topics ⇒ Array<String>
Lists all topics in the cluster.
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# File 'lib/kafka/client.rb', line 461 def topics @cluster.clear_target_topics @cluster.topics end |