Appendix A. Broker configuration parameters

zookeeper.connect

Type: string
Importance: high
Dynamic update: read-only

Zookeeper host string.

advertised.host.name

Type: string
Default: null
Importance: high
Dynamic update: read-only

DEPRECATED: only used when advertised.listeners or listeners are not set. Use advertised.listeners instead. Hostname to publish to ZooKeeper for clients to use. In IaaS environments, this may need to be different from the interface to which the broker binds. If this is not set, it will use the value for host.name if configured. Otherwise it will use the value returned from java.net.InetAddress.getCanonicalHostName().

advertised.listeners

Type: string
Default: null
Importance: high
Dynamic update: per-broker

Listeners to publish to ZooKeeper for clients to use, if different than the listeners config property. In IaaS environments, this may need to be different from the interface to which the broker binds. If this is not set, the value for listeners will be used. Unlike listeners it is not valid to advertise the 0.0.0.0 meta-address.

advertised.port

Type: int
Default: null
Importance: high
Dynamic update: read-only

DEPRECATED: only used when advertised.listeners or listeners are not set. Use advertised.listeners instead. The port to publish to ZooKeeper for clients to use. In IaaS environments, this may need to be different from the port to which the broker binds. If this is not set, it will publish the same port that the broker binds to.

auto.create.topics.enable

Type: boolean
Default: true
Importance: high
Dynamic update: read-only

Enable auto creation of topic on the server.

auto.leader.rebalance.enable

Type: boolean
Default: true
Importance: high
Dynamic update: read-only

Enables auto leader balancing. A background thread checks and triggers leader balance if required at regular intervals.

background.threads

Type: int
Default: 10
Valid Values: [1,…​]
Importance: high
Dynamic update: cluster-wide

The number of threads to use for various background processing tasks.

broker.id

Type: int
Default: -1
Importance: high
Dynamic update: read-only

The broker id for this server. If unset, a unique broker id will be generated.To avoid conflicts between zookeeper generated broker id’s and user configured broker id’s, generated broker ids start from reserved.broker.max.id + 1.

compression.type

Type: string
Default: producer
Importance: high
Dynamic update: cluster-wide

Specify the final compression type for a given topic. This configuration accepts the standard compression codecs ('gzip', 'snappy', 'lz4'). It additionally accepts 'uncompressed' which is equivalent to no compression; and 'producer' which means retain the original compression codec set by the producer.

delete.topic.enable

Type: boolean
Default: true
Importance: high
Dynamic update: read-only

Enables delete topic. Delete topic through the admin tool will have no effect if this config is turned off.

host.name

Type: string
Default: ""
Importance: high
Dynamic update: read-only

DEPRECATED: only used when listeners is not set. Use listeners instead. hostname of broker. If this is set, it will only bind to this address. If this is not set, it will bind to all interfaces.

leader.imbalance.check.interval.seconds

Type: long
Default: 300
Importance: high
Dynamic update: read-only

The frequency with which the partition rebalance check is triggered by the controller.

leader.imbalance.per.broker.percentage

Type: int
Default: 10
Importance: high
Dynamic update: read-only

The ratio of leader imbalance allowed per broker. The controller would trigger a leader balance if it goes above this value per broker. The value is specified in percentage.

listeners

Type: string
Default: null
Importance: high
Dynamic update: per-broker

Listener List - Comma-separated list of URIs we will listen on and the listener names. If the listener name is not a security protocol, listener.security.protocol.map must also be set. Specify hostname as 0.0.0.0 to bind to all interfaces. Leave hostname empty to bind to default interface. Examples of legal listener lists: PLAINTEXT://myhost:9092,SSL://:9091 CLIENT://0.0.0.0:9092,REPLICATION://localhost:9093.

log.dir

Type: string
Default: /tmp/kafka-logs
Importance: high
Dynamic update: read-only

The directory in which the log data is kept (supplemental for log.dirs property).

log.dirs

Type: string
Default: null
Importance: high
Dynamic update: read-only

The directories in which the log data is kept. If not set, the value in log.dir is used.

log.flush.interval.messages

Type: long
Default: 9223372036854775807
Valid Values: [1,…​]
Importance: high
Dynamic update: cluster-wide

The number of messages accumulated on a log partition before messages are flushed to disk.

log.flush.interval.ms

Type: long
Default: null
Importance: high
Dynamic update: cluster-wide

The maximum time in ms that a message in any topic is kept in memory before flushed to disk. If not set, the value in log.flush.scheduler.interval.ms is used.

log.flush.offset.checkpoint.interval.ms

Type: int
Default: 60000
Valid Values: [0,…​]
Importance: high
Dynamic update: read-only

The frequency with which we update the persistent record of the last flush which acts as the log recovery point.

log.flush.scheduler.interval.ms

Type: long
Default: 9223372036854775807
Importance: high
Dynamic update: read-only

The frequency in ms that the log flusher checks whether any log needs to be flushed to disk.

log.flush.start.offset.checkpoint.interval.ms

Type: int
Default: 60000
Valid Values: [0,…​]
Importance: high
Dynamic update: read-only

The frequency with which we update the persistent record of log start offset.

log.retention.bytes

Type: long
Default: -1
Importance: high
Dynamic update: cluster-wide

The maximum size of the log before deleting it.

log.retention.hours

Type: int
Default: 168
Importance: high
Dynamic update: read-only

The number of hours to keep a log file before deleting it (in hours), tertiary to log.retention.ms property.

log.retention.minutes

Type: int
Default: null
Importance: high
Dynamic update: read-only

The number of minutes to keep a log file before deleting it (in minutes), secondary to log.retention.ms property. If not set, the value in log.retention.hours is used.

log.retention.ms

Type: long
Default: null
Importance: high
Dynamic update: cluster-wide

The number of milliseconds to keep a log file before deleting it (in milliseconds), If not set, the value in log.retention.minutes is used.

log.roll.hours

Type: int
Default: 168
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The maximum time before a new log segment is rolled out (in hours), secondary to log.roll.ms property.

log.roll.jitter.hours

Type: int
Default: 0
Valid Values: [0,…​]
Importance: high
Dynamic update: read-only

The maximum jitter to subtract from logRollTimeMillis (in hours), secondary to log.roll.jitter.ms property.

log.roll.jitter.ms

Type: long
Default: null
Importance: high
Dynamic update: cluster-wide

The maximum jitter to subtract from logRollTimeMillis (in milliseconds). If not set, the value in log.roll.jitter.hours is used.

log.roll.ms

Type: long
Default: null
Importance: high
Dynamic update: cluster-wide

The maximum time before a new log segment is rolled out (in milliseconds). If not set, the value in log.roll.hours is used.

log.segment.bytes

Type: int
Default: 1073741824
Valid Values: [14,…​]
Importance: high
Dynamic update: cluster-wide

The maximum size of a single log file.

log.segment.delete.delay.ms

Type: long
Default: 60000
Valid Values: [0,…​]
Importance: high
Dynamic update: cluster-wide

The amount of time to wait before deleting a file from the filesystem.

message.max.bytes

Type: int
Default: 1000012
Valid Values: [0,…​]
Importance: high
Dynamic update: cluster-wide

The largest record batch size allowed by Kafka. If this is increased and there are consumers older than 0.10.2, the consumers' fetch size must also be increased so that the they can fetch record batches this large.

In the latest message format version, records are always grouped into batches for efficiency. In previous message format versions, uncompressed records are not grouped into batches and this limit only applies to a single record in that case.

This can be set per topic with the topic level max.message.bytes config.

min.insync.replicas

Type: int
Default: 1
Valid Values: [1,…​]
Importance: high
Dynamic update: cluster-wide

When a producer sets acks to "all" (or "-1"), min.insync.replicas specifies the minimum number of replicas that must acknowledge a write for the write to be considered successful. If this minimum cannot be met, then the producer will raise an exception (either NotEnoughReplicas or NotEnoughReplicasAfterAppend). When used together, min.insync.replicas and acks allow you to enforce greater durability guarantees. A typical scenario would be to create a topic with a replication factor of 3, set min.insync.replicas to 2, and produce with acks of "all". This will ensure that the producer raises an exception if a majority of replicas do not receive a write.

num.io.threads

Type: int
Default: 8
Valid Values: [1,…​]
Importance: high
Dynamic update: cluster-wide

The number of threads that the server uses for processing requests, which may include disk I/O.

num.network.threads

Type: int
Default: 3
Valid Values: [1,…​]
Importance: high
Dynamic update: cluster-wide

The number of threads that the server uses for receiving requests from the network and sending responses to the network.

num.recovery.threads.per.data.dir

Type: int
Default: 1
Valid Values: [1,…​]
Importance: high
Dynamic update: cluster-wide

The number of threads per data directory to be used for log recovery at startup and flushing at shutdown.

num.replica.alter.log.dirs.threads

Type: int
Default: null
Importance: high
Dynamic update: read-only

The number of threads that can move replicas between log directories, which may include disk I/O.

num.replica.fetchers

Type: int
Default: 1
Importance: high
Dynamic update: cluster-wide

Number of fetcher threads used to replicate messages from a source broker. Increasing this value can increase the degree of I/O parallelism in the follower broker.

offset.metadata.max.bytes

Type: int
Default: 4096
Importance: high
Dynamic update: read-only

The maximum size for a metadata entry associated with an offset commit.

offsets.commit.required.acks

Type: short
Default: -1
Importance: high
Dynamic update: read-only

The required acks before the commit can be accepted. In general, the default (-1) should not be overridden.

offsets.commit.timeout.ms

Type: int
Default: 5000
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

Offset commit will be delayed until all replicas for the offsets topic receive the commit or this timeout is reached. This is similar to the producer request timeout.

offsets.load.buffer.size

Type: int
Default: 5242880
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

Batch size for reading from the offsets segments when loading offsets into the cache.

offsets.retention.check.interval.ms

Type: long
Default: 600000
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

Frequency at which to check for stale offsets.

offsets.retention.minutes

Type: int
Default: 10080
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

Offsets older than this retention period will be discarded.

offsets.topic.compression.codec

Type: int
Default: 0
Importance: high
Dynamic update: read-only

Compression codec for the offsets topic - compression may be used to achieve "atomic" commits.

offsets.topic.num.partitions

Type: int
Default: 50
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The number of partitions for the offset commit topic (should not change after deployment).

offsets.topic.replication.factor

Type: short
Default: 3
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The replication factor for the offsets topic (set higher to ensure availability). Internal topic creation will fail until the cluster size meets this replication factor requirement.

offsets.topic.segment.bytes

Type: int
Default: 104857600
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The offsets topic segment bytes should be kept relatively small in order to facilitate faster log compaction and cache loads.

port

Type: int
Default: 9092
Importance: high
Dynamic update: read-only

DEPRECATED: only used when listeners is not set. Use listeners instead. the port to listen and accept connections on.

queued.max.requests

Type: int
Default: 500
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The number of queued requests allowed before blocking the network threads.

quota.consumer.default

Type: long
Default: 9223372036854775807
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

DEPRECATED: Used only when dynamic default quotas are not configured for <user, <client-id> or <user, client-id> in Zookeeper. Any consumer distinguished by clientId/consumer group will get throttled if it fetches more bytes than this value per-second.

quota.producer.default

Type: long
Default: 9223372036854775807
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

DEPRECATED: Used only when dynamic default quotas are not configured for <user>, <client-id> or <user, client-id> in Zookeeper. Any producer distinguished by clientId will get throttled if it produces more bytes than this value per-second.

replica.fetch.min.bytes

Type: int
Default: 1
Importance: high
Dynamic update: read-only

Minimum bytes expected for each fetch response. If not enough bytes, wait up to replicaMaxWaitTimeMs.

replica.fetch.wait.max.ms

Type: int
Default: 500
Importance: high
Dynamic update: read-only

max wait time for each fetcher request issued by follower replicas. This value should always be less than the replica.lag.time.max.ms at all times to prevent frequent shrinking of ISR for low throughput topics.

replica.high.watermark.checkpoint.interval.ms

Type: long
Default: 5000
Importance: high
Dynamic update: read-only

The frequency with which the high watermark is saved out to disk.

replica.lag.time.max.ms

Type: long
Default: 10000
Importance: high
Dynamic update: read-only

If a follower hasn’t sent any fetch requests or hasn’t consumed up to the leaders log end offset for at least this time, the leader will remove the follower from isr.

replica.socket.receive.buffer.bytes

Type: int
Default: 65536
Importance: high
Dynamic update: read-only

The socket receive buffer for network requests.

replica.socket.timeout.ms

Type: int
Default: 30000
Importance: high
Dynamic update: read-only

The socket timeout for network requests. Its value should be at least replica.fetch.wait.max.ms.

request.timeout.ms

Type: int
Default: 30000
Importance: high
Dynamic update: read-only

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.

socket.receive.buffer.bytes

Type: int
Default: 102400
Importance: high
Dynamic update: read-only

The SO_RCVBUF buffer of the socket sever sockets. If the value is -1, the OS default will be used.

socket.request.max.bytes

Type: int
Default: 104857600
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The maximum number of bytes in a socket request.

socket.send.buffer.bytes

Type: int
Default: 102400
Importance: high
Dynamic update: read-only

The SO_SNDBUF buffer of the socket sever sockets. If the value is -1, the OS default will be used.

transaction.max.timeout.ms

Type: int
Default: 900000
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The maximum allowed timeout for transactions. If a client’s requested transaction time exceed this, then the broker will return an error in InitProducerIdRequest. This prevents a client from too large of a timeout, which can stall consumers reading from topics included in the transaction.

transaction.state.log.load.buffer.size

Type: int
Default: 5242880
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

Batch size for reading from the transaction log segments when loading producer ids and transactions into the cache.

transaction.state.log.min.isr

Type: int
Default: 2
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

Overridden min.insync.replicas config for the transaction topic.

transaction.state.log.num.partitions

Type: int
Default: 50
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The number of partitions for the transaction topic (should not change after deployment).

transaction.state.log.replication.factor

Type: short
Default: 3
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The replication factor for the transaction topic (set higher to ensure availability). Internal topic creation will fail until the cluster size meets this replication factor requirement.

transaction.state.log.segment.bytes

Type: int
Default: 104857600
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The transaction topic segment bytes should be kept relatively small in order to facilitate faster log compaction and cache loads.

transactional.id.expiration.ms

Type: int
Default: 604800000
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The maximum amount of time in ms that the transaction coordinator will wait before proactively expire a producer’s transactional id without receiving any transaction status updates from it.

unclean.leader.election.enable

Type: boolean
Default: false
Importance: high
Dynamic update: cluster-wide

Indicates whether to enable replicas not in the ISR set to be elected as leader as a last resort, even though doing so may result in data loss.

zookeeper.connection.timeout.ms

Type: int
Default: null
Importance: high
Dynamic update: read-only

The max time that the client waits to establish a connection to zookeeper. If not set, the value in zookeeper.session.timeout.ms is used.

zookeeper.max.in.flight.requests

Type: int
Default: 10
Valid Values: [1,…​]
Importance: high
Dynamic update: read-only

The maximum number of unacknowledged requests the client will send to Zookeeper before blocking.

zookeeper.session.timeout.ms

Type: int
Default: 6000
Importance: high
Dynamic update: read-only

Zookeeper session timeout.

zookeeper.set.acl

Type: boolean
Default: false
Importance: high
Dynamic update: read-only

Set client to use secure ACLs.

broker.id.generation.enable

Type: boolean
Default: true
Importance: medium
Dynamic update: read-only

Enable automatic broker id generation on the server. When enabled the value configured for reserved.broker.max.id should be reviewed.

broker.rack

Type: string
Default: null
Importance: medium
Dynamic update: read-only

Rack of the broker. This will be used in rack aware replication assignment for fault tolerance. Examples: RACK1, us-east-1d.

connections.max.idle.ms

Type: long
Default: 600000
Importance: medium
Dynamic update: read-only

Idle connections timeout: the server socket processor threads close the connections that idle more than this.

controlled.shutdown.enable

Type: boolean
Default: true
Importance: medium
Dynamic update: read-only

Enable controlled shutdown of the server.

controlled.shutdown.max.retries

Type: int
Default: 3
Importance: medium
Dynamic update: read-only

Controlled shutdown can fail for multiple reasons. This determines the number of retries when such failure happens.

controlled.shutdown.retry.backoff.ms

Type: long
Default: 5000
Importance: medium
Dynamic update: read-only

Before each retry, the system needs time to recover from the state that caused the previous failure (Controller fail over, replica lag etc). This config determines the amount of time to wait before retrying.

controller.socket.timeout.ms

Type: int
Default: 30000
Importance: medium
Dynamic update: read-only

The socket timeout for controller-to-broker channels.

default.replication.factor

Type: int
Default: 1
Importance: medium
Dynamic update: read-only

default replication factors for automatically created topics.

delegation.token.expiry.time.ms

Type: long
Default: 86400000
Valid Values: [1,…​]
Importance: medium
Dynamic update: read-only

The token validity time in seconds before the token needs to be renewed. Default value 1 day.

delegation.token.master.key

Type: password
Default: null
Importance: medium
Dynamic update: read-only

Master/secret key to generate and verify delegation tokens. Same key must be configured across all the brokers. If the key is not set or set to empty string, brokers will disable the delegation token support.

delegation.token.max.lifetime.ms

Type: long
Default: 604800000
Valid Values: [1,…​]
Importance: medium
Dynamic update: read-only

The token has a maximum lifetime beyond which it cannot be renewed anymore. Default value 7 days.

delete.records.purgatory.purge.interval.requests

Type: int
Default: 1
Importance: medium
Dynamic update: read-only

The purge interval (in number of requests) of the delete records request purgatory.

fetch.purgatory.purge.interval.requests

Type: int
Default: 1000
Importance: medium
Dynamic update: read-only

The purge interval (in number of requests) of the fetch request purgatory.

group.initial.rebalance.delay.ms

Type: int
Default: 3000
Importance: medium
Dynamic update: read-only

The amount of time the group coordinator will wait for more consumers to join a new group before performing the first rebalance. A longer delay means potentially fewer rebalances, but increases the time until processing begins.

group.max.session.timeout.ms

Type: int
Default: 300000
Importance: medium
Dynamic update: read-only

The maximum allowed session timeout for registered consumers. Longer timeouts give consumers more time to process messages in between heartbeats at the cost of a longer time to detect failures.

group.min.session.timeout.ms

Type: int
Default: 6000
Importance: medium
Dynamic update: read-only

The minimum allowed session timeout for registered consumers. Shorter timeouts result in quicker failure detection at the cost of more frequent consumer heartbeating, which can overwhelm broker resources.

inter.broker.listener.name

Type: string
Default: null
Importance: medium
Dynamic update: read-only

Name of listener used for communication between brokers. If this is unset, the listener name is defined by security.inter.broker.protocol. It is an error to set this and security.inter.broker.protocol properties at the same time.

inter.broker.protocol.version

Type: string
Default: 2.0-IV1
Importance: medium
Dynamic update: read-only

Specify which version of the inter-broker protocol will be used. This is typically bumped after all brokers were upgraded to a new version. Example of some valid values are: 0.8.0, 0.8.1, 0.8.1.1, 0.8.2, 0.8.2.0, 0.8.2.1, 0.9.0.0, 0.9.0.1 Check ApiVersion for the full list.

log.cleaner.backoff.ms

Type: long
Default: 15000
Valid Values: [0,…​]
Importance: medium
Dynamic update: cluster-wide

The amount of time to sleep when there are no logs to clean.

log.cleaner.dedupe.buffer.size

Type: long
Default: 134217728
Importance: medium
Dynamic update: cluster-wide

The total memory used for log deduplication across all cleaner threads.

log.cleaner.delete.retention.ms

Type: long
Default: 86400000
Importance: medium
Dynamic update: cluster-wide

How long are delete records retained?

log.cleaner.enable

Type: boolean
Default: true
Importance: medium
Dynamic update: read-only

Enable the log cleaner process to run on the server. Should be enabled if using any topics with a cleanup.policy=compact including the internal offsets topic. If disabled those topics will not be compacted and continually grow in size.

log.cleaner.io.buffer.load.factor

Type: double
Default: 0.9
Importance: medium
Dynamic update: cluster-wide

Log cleaner dedupe buffer load factor. The percentage full the dedupe buffer can become. A higher value will allow more log to be cleaned at once but will lead to more hash collisions.

log.cleaner.io.buffer.size

Type: int
Default: 524288
Valid Values: [0,…​]
Importance: medium
Dynamic update: cluster-wide

The total memory used for log cleaner I/O buffers across all cleaner threads.

log.cleaner.io.max.bytes.per.second

Type: double
Default: 1.7976931348623157E308
Importance: medium
Dynamic update: cluster-wide

The log cleaner will be throttled so that the sum of its read and write i/o will be less than this value on average.

log.cleaner.min.cleanable.ratio

Type: double
Default: 0.5
Importance: medium
Dynamic update: cluster-wide

The minimum ratio of dirty log to total log for a log to eligible for cleaning.

log.cleaner.min.compaction.lag.ms

Type: long
Default: 0
Importance: medium
Dynamic update: cluster-wide

The minimum time a message will remain uncompacted in the log. Only applicable for logs that are being compacted.

log.cleaner.threads

Type: int
Default: 1
Valid Values: [0,…​]
Importance: medium
Dynamic update: cluster-wide

The number of background threads to use for log cleaning.

log.cleanup.policy

Type: list
Default: delete
Valid Values: [compact, delete]
Importance: medium
Dynamic update: cluster-wide

The default cleanup policy for segments beyond the retention window. A comma separated list of valid policies. Valid policies are: "delete" and "compact".

log.index.interval.bytes

Type: int
Default: 4096
Valid Values: [0,…​]
Importance: medium
Dynamic update: cluster-wide

The interval with which we add an entry to the offset index.

log.index.size.max.bytes

Type: int
Default: 10485760
Valid Values: [4,…​]
Importance: medium
Dynamic update: cluster-wide

The maximum size in bytes of the offset index.

log.message.format.version

Type: string
Default: 2.0-IV1
Importance: medium
Dynamic update: read-only

Specify the message format version the broker will use to append messages to the logs. The value should be a valid ApiVersion. Some examples are: 0.8.2, 0.9.0.0, 0.10.0, check ApiVersion for more details. By setting a particular message format version, the user is certifying that all the existing messages on disk are smaller or equal than the specified version. Setting this value incorrectly will cause consumers with older versions to break as they will receive messages with a format that they don’t understand.

log.message.timestamp.difference.max.ms

Type: long
Default: 9223372036854775807
Importance: medium
Dynamic update: cluster-wide

The maximum difference allowed between the timestamp when a broker receives a message and the timestamp specified in the message. If log.message.timestamp.type=CreateTime, a message will be rejected if the difference in timestamp exceeds this threshold. This configuration is ignored if log.message.timestamp.type=LogAppendTime.The maximum timestamp difference allowed should be no greater than log.retention.ms to avoid unnecessarily frequent log rolling.

log.message.timestamp.type

Type: string
Default: CreateTime
Valid Values: [CreateTime, LogAppendTime]
Importance: medium
Dynamic update: cluster-wide

Define whether the timestamp in the message is message create time or log append time. The value should be either CreateTime or LogAppendTime.

log.preallocate

Type: boolean
Default: false
Importance: medium
Dynamic update: cluster-wide

Should pre allocate file when create new segment? If you are using Kafka on Windows, you probably need to set it to true.

log.retention.check.interval.ms

Type: long
Default: 300000
Valid Values: [1,…​]
Importance: medium
Dynamic update: read-only

The frequency in milliseconds that the log cleaner checks whether any log is eligible for deletion.

max.connections.per.ip

Type: int
Default: 2147483647
Valid Values: [0,…​]
Importance: medium
Dynamic update: read-only

The maximum number of connections we allow from each ip address. This can be set to 0 if there are overrides configured using max.connections.per.ip.overrides property.

max.connections.per.ip.overrides

Type: string
Default: ""
Importance: medium
Dynamic update: read-only

A comma-separated list of per-ip or hostname overrides to the default maximum number of connections. An example value is "hostName:100,127.0.0.1:200".

max.incremental.fetch.session.cache.slots

Type: int
Default: 1000
Valid Values: [0,…​]
Importance: medium
Dynamic update: read-only

The maximum number of incremental fetch sessions that we will maintain.

num.partitions

Type: int
Default: 1
Valid Values: [1,…​]
Importance: medium
Dynamic update: read-only

The default number of log partitions per topic.

password.encoder.old.secret

Type: password
Default: null
Importance: medium
Dynamic update: read-only

The old secret that was used for encoding dynamically configured passwords. This is required only when the secret is updated. If specified, all dynamically encoded passwords are decoded using this old secret and re-encoded using password.encoder.secret when broker starts up.

password.encoder.secret

Type: password
Default: null
Importance: medium
Dynamic update: read-only

The secret used for encoding dynamically configured passwords for this broker.

principal.builder.class

Type: class
Default: null
Importance: medium
Dynamic update: per-broker

The fully qualified name of a class that implements the KafkaPrincipalBuilder interface, which is used to build the KafkaPrincipal object used during authorization. This config also supports the deprecated PrincipalBuilder interface which was previously used for client authentication over SSL. If no principal builder is defined, the default behavior depends on the security protocol in use. For SSL authentication, the principal name will be the distinguished name from the client certificate if one is provided; otherwise, if client authentication is not required, the principal name will be ANONYMOUS. For SASL authentication, the principal will be derived using the rules defined by sasl.kerberos.principal.to.local.rules if GSSAPI is in use, and the SASL authentication ID for other mechanisms. For PLAINTEXT, the principal will be ANONYMOUS.

producer.purgatory.purge.interval.requests

Type: int
Default: 1000
Importance: medium
Dynamic update: read-only

The purge interval (in number of requests) of the producer request purgatory.

queued.max.request.bytes

Type: long
Default: -1
Importance: medium
Dynamic update: read-only

The number of queued bytes allowed before no more requests are read.

replica.fetch.backoff.ms

Type: int
Default: 1000
Valid Values: [0,…​]
Importance: medium
Dynamic update: read-only

The amount of time to sleep when fetch partition error occurs.

replica.fetch.max.bytes

Type: int
Default: 1048576
Valid Values: [0,…​]
Importance: medium
Dynamic update: read-only

The number of bytes of messages to attempt to fetch for each partition. This is not an absolute maximum, if the first record batch in the first non-empty partition of the fetch is larger than this value, the record batch will still be returned to ensure that progress can be made. The maximum record batch size accepted by the broker is defined via message.max.bytes (broker config) or max.message.bytes (topic config).

replica.fetch.response.max.bytes

Type: int
Default: 10485760
Valid Values: [0,…​]
Importance: medium
Dynamic update: read-only

Maximum bytes expected for the entire fetch response. Records are fetched in batches, and if the first record batch in the first non-empty partition of the fetch is larger than this value, the record batch will still be returned to ensure that progress can be made. As such, this is not an absolute maximum. The maximum record batch size accepted by the broker is defined via message.max.bytes (broker config) or max.message.bytes (topic config).

reserved.broker.max.id

Type: int
Default: 1000
Valid Values: [0,…​]
Importance: medium
Dynamic update: read-only

Max number that can be used for a broker.id.

sasl.client.callback.handler.class

Type: class
Default: null
Importance: medium
Dynamic update: read-only

The fully qualified name of a SASL client callback handler class that implements the AuthenticateCallbackHandler interface.

sasl.enabled.mechanisms

Type: list
Default: GSSAPI
Importance: medium
Dynamic update: per-broker

The list of SASL mechanisms enabled in the Kafka server. The list may contain any mechanism for which a security provider is available. Only GSSAPI is enabled by default.

sasl.jaas.config

Type: password
Default: null
Importance: medium
Dynamic update: per-broker

JAAS login context parameters for SASL connections in the format used by JAAS configuration files. JAAS configuration file format is described here. The format for the value is: ‘loginModuleClass controlFlag (optionName=optionValue)*;’. For brokers, the config must be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.scram-sha-256.sasl.jaas.config=com.example.ScramLoginModule required;.

sasl.kerberos.kinit.cmd

Type: string
Default: /usr/bin/kinit
Importance: medium
Dynamic update: per-broker

Kerberos kinit command path.

sasl.kerberos.min.time.before.relogin

Type: long
Default: 60000
Importance: medium
Dynamic update: per-broker

Login thread sleep time between refresh attempts.

sasl.kerberos.principal.to.local.rules

Type: list
Default: DEFAULT
Importance: medium
Dynamic update: per-broker

A list of rules for mapping from principal names to short names (typically operating system usernames). The rules are evaluated in order and the first rule that matches a principal name is used to map it to a short name. Any later rules in the list are ignored. By default, principal names of the form {username}/{hostname}@{REALM} are mapped to {username}. For more details on the format please see #security_authz[ security authorization and acls]. Note that this configuration is ignored if an extension of KafkaPrincipalBuilder is provided by the principal.builder.class configuration.

sasl.kerberos.service.name

Type: string
Default: null
Importance: medium
Dynamic update: per-broker

The Kerberos principal name that Kafka runs as. This can be defined either in Kafka’s JAAS config or in Kafka’s config.

sasl.kerberos.ticket.renew.jitter

Type: double
Default: 0.05
Importance: medium
Dynamic update: per-broker

Percentage of random jitter added to the renewal time.

sasl.kerberos.ticket.renew.window.factor

Type: double
Default: 0.8
Importance: medium
Dynamic update: per-broker

Login thread will sleep until the specified window factor of time from last refresh to ticket’s expiry has been reached, at which time it will try to renew the ticket.

sasl.login.callback.handler.class

Type: class
Default: null
Importance: medium
Dynamic update: read-only

The fully qualified name of a SASL login callback handler class that implements the AuthenticateCallbackHandler interface. For brokers, login callback handler config must be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.scram-sha-256.sasl.login.callback.handler.class=com.example.CustomScramLoginCallbackHandler.

sasl.login.class

Type: class
Default: null
Importance: medium
Dynamic update: read-only

The fully qualified name of a class that implements the Login interface. For brokers, login config must be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.scram-sha-256.sasl.login.class=com.example.CustomScramLogin.

sasl.login.refresh.buffer.seconds

Type: short
Default: 300
Importance: medium
Dynamic update: per-broker

The amount of buffer time before credential expiration to maintain when refreshing a credential, in seconds. If a refresh would otherwise occur closer to expiration than the number of buffer seconds then the refresh will be moved up to maintain as much of the buffer time as possible. Legal values are between 0 and 3600 (1 hour); a default value of 300 (5 minutes) is used if no value is specified. This value and sasl.login.refresh.min.period.seconds are both ignored if their sum exceeds the remaining lifetime of a credential. Currently applies only to OAUTHBEARER.

sasl.login.refresh.min.period.seconds

Type: short
Default: 60
Importance: medium
Dynamic update: per-broker

The desired minimum time for the login refresh thread to wait before refreshing a credential, in seconds. Legal values are between 0 and 900 (15 minutes); a default value of 60 (1 minute) is used if no value is specified. This value and sasl.login.refresh.buffer.seconds are both ignored if their sum exceeds the remaining lifetime of a credential. Currently applies only to OAUTHBEARER.

sasl.login.refresh.window.factor

Type: double
Default: 0.8
Importance: medium
Dynamic update: per-broker

Login refresh thread will sleep until the specified window factor relative to the credential’s lifetime has been reached, at which time it will try to refresh the credential. Legal values are between 0.5 (50%) and 1.0 (100%) inclusive; a default value of 0.8 (80%) is used if no value is specified. Currently applies only to OAUTHBEARER.

sasl.login.refresh.window.jitter

Type: double
Default: 0.05
Importance: medium
Dynamic update: per-broker

The maximum amount of random jitter relative to the credential’s lifetime that is added to the login refresh thread’s sleep time. Legal values are between 0 and 0.25 (25%) inclusive; a default value of 0.05 (5%) is used if no value is specified. Currently applies only to OAUTHBEARER.

sasl.mechanism.inter.broker.protocol

Type: string
Default: GSSAPI
Importance: medium
Dynamic update: per-broker

SASL mechanism used for inter-broker communication. Default is GSSAPI.

sasl.server.callback.handler.class

Type: class
Default: null
Importance: medium
Dynamic update: read-only

The fully qualified name of a SASL server callback handler class that implements the AuthenticateCallbackHandler interface. Server callback handlers must be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.plain.sasl.server.callback.handler.class=com.example.CustomPlainCallbackHandler.

security.inter.broker.protocol

Type: string
Default: PLAINTEXT
Importance: medium
Dynamic update: read-only

Security protocol used to communicate between brokers. Valid values are: PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL. It is an error to set this and inter.broker.listener.name properties at the same time.

ssl.cipher.suites

Type: list
Default: ""
Importance: medium
Dynamic update: per-broker

A list of cipher suites. This is a named combination of authentication, encryption, MAC and key exchange algorithm used to negotiate the security settings for a network connection using TLS or SSL network protocol. By default all the available cipher suites are supported.

ssl.client.auth

Type: string
Default: none
Valid Values: [required, requested, none]
Importance: medium
Dynamic update: per-broker

Configures kafka broker to request client authentication. The following settings are common:

  • ssl.client.auth=required If set to required client authentication is required.
  • ssl.client.auth=requested This means client authentication is optional. unlike requested , if this option is set client can choose not to provide authentication information about itself
  • ssl.client.auth=none This means client authentication is not needed.
ssl.enabled.protocols

Type: list
Default: TLSv1.2,TLSv1.1,TLSv1
Importance: medium
Dynamic update: per-broker

The list of protocols enabled for SSL connections.

ssl.key.password

Type: password
Default: null
Importance: medium
Dynamic update: per-broker

The password of the private key in the key store file. This is optional for client.

ssl.keymanager.algorithm

Type: string
Default: SunX509
Importance: medium
Dynamic update: per-broker

The algorithm used by key manager factory for SSL connections. Default value is the key manager factory algorithm configured for the Java Virtual Machine.

ssl.keystore.location

Type: string
Default: null
Importance: medium
Dynamic update: per-broker

The location of the key store file. This is optional for client and can be used for two-way authentication for client.

ssl.keystore.password

Type: password
Default: null
Importance: medium
Dynamic update: per-broker

The store password for the key store file. This is optional for client and only needed if ssl.keystore.location is configured.

ssl.keystore.type

Type: string
Default: JKS
Importance: medium
Dynamic update: per-broker

The file format of the key store file. This is optional for client.

ssl.protocol

Type: string
Default: TLS
Importance: medium
Dynamic update: per-broker

The SSL protocol used to generate the SSLContext. Default setting is TLS, which is fine for most cases. Allowed values in recent JVMs are TLS, TLSv1.1 and TLSv1.2. SSL, SSLv2 and SSLv3 may be supported in older JVMs, but their usage is discouraged due to known security vulnerabilities.

ssl.provider

Type: string
Default: null
Importance: medium
Dynamic update: per-broker

The name of the security provider used for SSL connections. Default value is the default security provider of the JVM.

ssl.trustmanager.algorithm

Type: string
Default: PKIX
Importance: medium
Dynamic update: per-broker

The algorithm used by trust manager factory for SSL connections. Default value is the trust manager factory algorithm configured for the Java Virtual Machine.

ssl.truststore.location

Type: string
Default: null
Importance: medium
Dynamic update: per-broker

The location of the trust store file.

ssl.truststore.password

Type: password
Default: null
Importance: medium
Dynamic update: per-broker

The password for the trust store file. If a password is not set access to the truststore is still available, but integrity checking is disabled.

ssl.truststore.type

Type: string
Default: JKS
Importance: medium
Dynamic update: per-broker

The file format of the trust store file.

alter.config.policy.class.name

Type: class
Default: null
Importance: low
Dynamic update: read-only

The alter configs policy class that should be used for validation. The class should implement the org.apache.kafka.server.policy.AlterConfigPolicy interface.

alter.log.dirs.replication.quota.window.num

Type: int
Default: 11
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The number of samples to retain in memory for alter log dirs replication quotas.

alter.log.dirs.replication.quota.window.size.seconds

Type: int
Default: 1
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The time span of each sample for alter log dirs replication quotas.

authorizer.class.name

Type: string
Default: ""
Importance: low
Dynamic update: read-only

The authorizer class that should be used for authorization.

client.quota.callback.class

Type: class
Default: null
Importance: low
Dynamic update: read-only

The fully qualified name of a class that implements the ClientQuotaCallback interface, which is used to determine quota limits applied to client requests. By default, <user, client-id>, <user> or <client-id> quotas stored in ZooKeeper are applied. For any given request, the most specific quota that matches the user principal of the session and the client-id of the request is applied.

create.topic.policy.class.name

Type: class
Default: null
Importance: low
Dynamic update: read-only

The create topic policy class that should be used for validation. The class should implement the org.apache.kafka.server.policy.CreateTopicPolicy interface.

delegation.token.expiry.check.interval.ms

Type: long
Default: 3600000
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

Scan interval to remove expired delegation tokens.

listener.security.protocol.map

Type: string
Default: PLAINTEXT:PLAINTEXT,SSL:SSL,SASL_PLAINTEXT:SASL_PLAINTEXT,SASL_SSL:SASL_SSL
Importance: low
Dynamic update: per-broker

Map between listener names and security protocols. This must be defined for the same security protocol to be usable in more than one port or IP. For example, internal and external traffic can be separated even if SSL is required for both. Concretely, the user could define listeners with names INTERNAL and EXTERNAL and this property as: INTERNAL:SSL,EXTERNAL:SSL. As shown, key and value are separated by a colon and map entries are separated by commas. Each listener name should only appear once in the map. Different security (SSL and SASL) settings can be configured for each listener by adding a normalised prefix (the listener name is lowercased) to the config name. For example, to set a different keystore for the INTERNAL listener, a config with name listener.name.internal.ssl.keystore.location would be set. If the config for the listener name is not set, the config will fallback to the generic config (i.e. ssl.keystore.location).

log.message.downconversion.enable

Type: boolean
Default: true
Importance: low
Dynamic update: cluster-wide

This configuration controls whether down-conversion of message formats is enabled to satisfy consume requests. When set to false, broker will not perform down-conversion for consumers expecting an older message format. The broker responds with UNSUPPORTED_VERSION error for consume requests from such older clients. This configurationdoes not apply to any message format conversion that might be required for replication to followers.

metric.reporters

Type: list
Default: ""
Importance: low
Dynamic update: cluster-wide

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.

metrics.num.samples

Type: int
Default: 2
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The number of samples maintained to compute metrics.

metrics.recording.level

Type: string
Default: INFO
Importance: low
Dynamic update: read-only

The highest recording level for metrics.

metrics.sample.window.ms

Type: long
Default: 30000
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The window of time a metrics sample is computed over.

password.encoder.cipher.algorithm

Type: string
Default: AES/CBC/PKCS5Padding
Importance: low
Dynamic update: read-only

The Cipher algorithm used for encoding dynamically configured passwords.

password.encoder.iterations

Type: int
Default: 4096
Valid Values: [1024,…​]
Importance: low
Dynamic update: read-only

The iteration count used for encoding dynamically configured passwords.

password.encoder.key.length

Type: int
Default: 128
Valid Values: [8,…​]
Importance: low
Dynamic update: read-only

The key length used for encoding dynamically configured passwords.

password.encoder.keyfactory.algorithm

Type: string
Default: null
Importance: low
Dynamic update: read-only

The SecretKeyFactory algorithm used for encoding dynamically configured passwords. Default is PBKDF2WithHmacSHA512 if available and PBKDF2WithHmacSHA1 otherwise.

quota.window.num

Type: int
Default: 11
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The number of samples to retain in memory for client quotas.

quota.window.size.seconds

Type: int
Default: 1
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The time span of each sample for client quotas.

replication.quota.window.num

Type: int
Default: 11
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The number of samples to retain in memory for replication quotas.

replication.quota.window.size.seconds

Type: int
Default: 1
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The time span of each sample for replication quotas.

ssl.endpoint.identification.algorithm

Type: string
Default: https
Importance: low
Dynamic update: per-broker

The endpoint identification algorithm to validate server hostname using server certificate.

ssl.secure.random.implementation

Type: string
Default: null
Importance: low
Dynamic update: per-broker

The SecureRandom PRNG implementation to use for SSL cryptography operations.

transaction.abort.timed.out.transaction.cleanup.interval.ms

Type: int
Default: 60000
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The interval at which to rollback transactions that have timed out.

transaction.remove.expired.transaction.cleanup.interval.ms

Type: int
Default: 3600000
Valid Values: [1,…​]
Importance: low
Dynamic update: read-only

The interval at which to remove transactions that have expired due to transactional.id.expiration.ms passing.

zookeeper.sync.time.ms

Type: int
Default: 2000
Importance: low
Dynamic update: read-only

How far a ZK follower can be behind a ZK leader.