3.6 Kafka Streams Configs

Below is the configuration of the Kafka Streams client library.

  • application.id

    An identifier for the stream processing application. Must be unique within the Kafka cluster. It is used as 1) the default client-id prefix, 2) the group-id for membership management, 3) the changelog topic prefix.

    Type:string
    Default:
    Valid Values:
    Importance:high

  • bootstrap.servers

    A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. The client will make use of all servers irrespective of which servers are specified here for bootstrapping—this list only impacts the initial hosts used to discover the full set of servers. This list should be in the form host1:port1,host2:port2,.... Since these servers are just used for the initial connection to discover the full cluster membership (which may change dynamically), this list need not contain the full set of servers (you may want more than one, though, in case a server is down).

    Type:list
    Default:
    Valid Values:
    Importance:high

  • replication.factor

    The replication factor for change log topics and repartition topics created by the stream processing application.

    Type:int
    Default:1
    Valid Values:
    Importance:high

  • state.dir

    Directory location for state store. This path must be unique for each streams instance sharing the same underlying filesystem.

    Type:string
    Default:/tmp/kafka-streams
    Valid Values:
    Importance:high

  • acceptable.recovery.lag

    The maximum acceptable lag (number of offsets to catch up) for a client to be considered caught-up for an active task.Should correspond to a recovery time of well under a minute for a given workload. Must be at least 0.

    Type:long
    Default:10000
    Valid Values:[0,…]
    Importance:medium

  • cache.max.bytes.buffering

    Maximum number of memory bytes to be used for buffering across all threads

    Type:long
    Default:10485760
    Valid Values:[0,…]
    Importance:medium

  • client.id

    An ID prefix string used for the client IDs of internal consumer, producer and restore-consumer, with pattern ‘-StreamThread--‘.

    Type:string
    Default:“”
    Valid Values:
    Importance:medium

  • default.deserialization.exception.handler

    Exception handling class that implements the org.apache.kafka.streams.errors.DeserializationExceptionHandler interface.

    Type:class
    Default:org.apache.kafka.streams.errors.LogAndFailExceptionHandler
    Valid Values:
    Importance:medium

  • default.key.serde

    Default serializer / deserializer class for key that implements the org.apache.kafka.common.serialization.Serde interface. Note when windowed serde class is used, one needs to set the inner serde class that implements the org.apache.kafka.common.serialization.Serde interface via ‘default.windowed.key.serde.inner’ or ‘default.windowed.value.serde.inner’ as well

    Type:class
    Default:org.apache.kafka.common.serialization.Serdes$ByteArraySerde
    Valid Values:
    Importance:medium

  • default.production.exception.handler

    Exception handling class that implements the org.apache.kafka.streams.errors.ProductionExceptionHandler interface.

    Type:class
    Default:org.apache.kafka.streams.errors.DefaultProductionExceptionHandler
    Valid Values:
    Importance:medium

  • default.timestamp.extractor

    Default timestamp extractor class that implements the org.apache.kafka.streams.processor.TimestampExtractor interface.

    Type:class
    Default:org.apache.kafka.streams.processor.FailOnInvalidTimestamp
    Valid Values:
    Importance:medium

  • default.value.serde

    Default serializer / deserializer class for value that implements the org.apache.kafka.common.serialization.Serde interface. Note when windowed serde class is used, one needs to set the inner serde class that implements the org.apache.kafka.common.serialization.Serde interface via ‘default.windowed.key.serde.inner’ or ‘default.windowed.value.serde.inner’ as well

    Type:class
    Default:org.apache.kafka.common.serialization.Serdes$ByteArraySerde
    Valid Values:
    Importance:medium

  • default.windowed.key.serde.inner

    Default serializer / deserializer for the inner class of a windowed key. Must implement the org.apache.kafka.common.serialization.Serde interface.

    Type:class
    Default:null
    Valid Values:
    Importance:medium

  • default.windowed.value.serde.inner

    Default serializer / deserializer for the inner class of a windowed value. Must implement the org.apache.kafka.common.serialization.Serde interface.

    Type:class
    Default:null
    Valid Values:
    Importance:medium

  • max.task.idle.ms

    Maximum amount of time in milliseconds a stream task will stay idle when not all of its partition buffers contain records, to avoid potential out-of-order record processing across multiple input streams.

    Type:long
    Default:0
    Valid Values:
    Importance:medium

  • max.warmup.replicas

    The maximum number of warmup replicas (extra standbys beyond the configured num.standbys) that can be assigned at once for the purpose of keeping the task available on one instance while it is warming up on another instance it has been reassigned to. Used to throttle how much extra broker traffic and cluster state can be used for high availability. Must be at least 1.

    Type:int
    Default:2
    Valid Values:[1,…]
    Importance:medium

  • num.standby.replicas

    The number of standby replicas for each task.

    Type:int
    Default:0
    Valid Values:
    Importance:medium

  • num.stream.threads

    The number of threads to execute stream processing.

    Type:int
    Default:1
    Valid Values:
    Importance:medium

  • processing.guarantee

    The processing guarantee that should be used. Possible values are at_least_once (default), exactly_once (requires brokers version 0.11.0 or higher), and exactly_once_beta (requires brokers version 2.5 or higher). Note that exactly-once processing requires a cluster of at least three brokers by default what is the recommended setting for production; for development you can change this, by adjusting broker setting transaction.state.log.replication.factor and transaction.state.log.min.isr.

    Type:string
    Default:at_least_once
    Valid Values:[at_least_once, exactly_once, exactly_once_beta]
    Importance:medium

  • security.protocol

    Protocol used to communicate with brokers. Valid values are: PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL.

    Type:string
    Default:PLAINTEXT
    Valid Values:
    Importance:medium

  • task.timeout.ms

    The maximum amount of time in milliseconds a task might stall due to internal errors and retries until an error is raised. For a timeout of 0ms, a task would raise an error for the first internal error. For any timeout larger than 0ms, a task will retry at least once before an error is raised.

    Type:long
    Default:300000 (5 minutes)
    Valid Values:[0,…]
    Importance:medium

  • topology.optimization

    A configuration telling Kafka Streams if it should optimize the topology, disabled by default

    Type:string
    Default:none
    Valid Values:[none, all]
    Importance:medium

  • application.server

    A host:port pair pointing to a user-defined endpoint that can be used for state store discovery and interactive queries on this KafkaStreams instance.

    Type:string
    Default:“”
    Valid Values:
    Importance:low

  • buffered.records.per.partition

    Maximum number of records to buffer per partition.

    Type:int
    Default:1000
    Valid Values:
    Importance:low

  • built.in.metrics.version

    Version of the built-in metrics to use.

    Type:string
    Default:latest
    Valid Values:[0.10.0-2.4, latest]
    Importance:low

  • commit.interval.ms

    The frequency in milliseconds with which to save the position of the processor. (Note, if processing.guarantee is set to exactly_once, the default value is 100, otherwise the default value is 30000.

    Type:long
    Default:30000 (30 seconds)
    Valid Values:[0,…]
    Importance:low

  • connections.max.idle.ms

    Close idle connections after the number of milliseconds specified by this config.

    Type:long
    Default:540000 (9 minutes)
    Valid Values:
    Importance:low

  • metadata.max.age.ms

    The period of time in milliseconds after which we force a refresh of metadata even if we haven’t seen any partition leadership changes to proactively discover any new brokers or partitions.

    Type:long
    Default:300000 (5 minutes)
    Valid Values:[0,…]
    Importance:low

  • metric.reporters

    A list of classes to use as metrics reporters. Implementing the org.apache.kafka.common.metrics.MetricsReporter interface allows plugging in classes that will be notified of new metric creation. The JmxReporter is always included to register JMX statistics.

    Type:list
    Default:“”
    Valid Values:
    Importance:low

  • metrics.num.samples

    The number of samples maintained to compute metrics.

    Type:int
    Default:2
    Valid Values:[1,…]
    Importance:low

  • metrics.recording.level

    The highest recording level for metrics.

    Type:string
    Default:INFO
    Valid Values:[INFO, DEBUG, TRACE]
    Importance:low

  • metrics.sample.window.ms

    The window of time a metrics sample is computed over.

    Type:long
    Default:30000 (30 seconds)
    Valid Values:[0,…]
    Importance:low

  • partition.grouper

    Partition grouper class that implements the org.apache.kafka.streams.processor.PartitionGrouper interface. WARNING: This config is deprecated and will be removed in 3.0.0 release.

    Type:class
    Default:org.apache.kafka.streams.processor.DefaultPartitionGrouper
    Valid Values:
    Importance:low

  • poll.ms

    The amount of time in milliseconds to block waiting for input.

    Type:long
    Default:100
    Valid Values:
    Importance:low

  • probing.rebalance.interval.ms

    The maximum time in milliseconds to wait before triggering a rebalance to probe for warmup replicas that have finished warming up and are ready to become active. Probing rebalances will continue to be triggered until the assignment is balanced. Must be at least 1 minute.

    Type:long
    Default:600000 (10 minutes)
    Valid Values:[60000,…]
    Importance:low

  • receive.buffer.bytes

    The size of the TCP receive buffer (SO_RCVBUF) to use when reading data. If the value is -1, the OS default will be used.

    Type:int
    Default:32768 (32 kibibytes)
    Valid Values:[-1,…]
    Importance:low

  • reconnect.backoff.max.ms

    The maximum amount of time in milliseconds to wait when reconnecting to a broker that has repeatedly failed to connect. If provided, the backoff per host will increase exponentially for each consecutive connection failure, up to this maximum. After calculating the backoff increase, 20% random jitter is added to avoid connection storms.

    Type:long
    Default:1000 (1 second)
    Valid Values:[0,…]
    Importance:low

  • reconnect.backoff.ms

    The base amount of time to wait before attempting to reconnect to a given host. This avoids repeatedly connecting to a host in a tight loop. This backoff applies to all connection attempts by the client to a broker.

    Type:long
    Default:50
    Valid Values:[0,…]
    Importance:low

  • request.timeout.ms

    The configuration controls the maximum amount of time the client will wait for the response of a request. If the response is not received before the timeout elapses the client will resend the request if necessary or fail the request if retries are exhausted.

    Type:int
    Default:40000 (40 seconds)
    Valid Values:[0,…]
    Importance:low

  • retries

    Setting a value greater than zero will cause the client to resend any request that fails with a potentially transient error. It is recommended to set the value to either zero or `MAX_VALUE` and use corresponding timeout parameters to control how long a client should retry a request.

    Type:int
    Default:0
    Valid Values:[0,…,2147483647]
    Importance:low

  • retry.backoff.ms

    The amount of time to wait before attempting to retry a failed request to a given topic partition. This avoids repeatedly sending requests in a tight loop under some failure scenarios.

    Type:long
    Default:100
    Valid Values:[0,…]
    Importance:low

  • rocksdb.config.setter

    A Rocks DB config setter class or class name that implements the org.apache.kafka.streams.state.RocksDBConfigSetter interface

    Type:class
    Default:null
    Valid Values:
    Importance:low

  • send.buffer.bytes

    The size of the TCP send buffer (SO_SNDBUF) to use when sending data. If the value is -1, the OS default will be used.

    Type:int
    Default:131072 (128 kibibytes)
    Valid Values:[-1,…]
    Importance:low

  • state.cleanup.delay.ms

    The amount of time in milliseconds to wait before deleting state when a partition has migrated. Only state directories that have not been modified for at least state.cleanup.delay.ms will be removed

    Type:long
    Default:600000 (10 minutes)
    Valid Values:
    Importance:low

  • upgrade.from

    Allows upgrading in a backward compatible way. This is needed when upgrading from [0.10.0, 1.1] to 2.0+, or when upgrading from [2.0, 2.3] to 2.4+. When upgrading from 2.4 to a newer version it is not required to specify this config. Default is `null`. Accepted values are “0.10.0”, “0.10.1”, “0.10.2”, “0.11.0”, “1.0”, “1.1”, “2.0”, “2.1”, “2.2”, “2.3” (for upgrading from the corresponding old version).

    Type:string
    Default:null
    Valid Values:[null, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 1.0, 1.1, 2.0, 2.1, 2.2, 2.3]
    Importance:low

  • windowstore.changelog.additional.retention.ms

    Added to a windows maintainMs to ensure data is not deleted from the log prematurely. Allows for clock drift. Default is 1 day

    Type:long
    Default:86400000 (1 day)
    Valid Values:
    Importance:low