Chapter 1. Broker configuration properties 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. Also unlike listeners , there can be duplicated ports in this property, so that one listener can be configured to advertise another listener's address. This can be useful in some cases where external load balancers are used. 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 the distribution of partition leaders at regular intervals, configurable by leader.imbalance.check.interval.seconds . If the leader imbalance exceeds leader.imbalance.per.broker.percentage , leader rebalance to the preferred leader for partitions is triggered. 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 Valid Values: [uncompressed, zstd, lz4, snappy, gzip, 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', 'zstd'). It additionally accepts 'uncompressed' which is equivalent to no compression; and 'producer' which means retain the original compression codec set by the producer. control.plane.listener.name Type: string Default: null Importance: high Dynamic update: read-only Name of listener used for communication between controller and brokers. Broker will use the control.plane.listener.name to locate the endpoint in listeners list, to listen for connections from the controller. For example, if a broker's config is : listeners = INTERNAL://192.1.1.8:9092, EXTERNAL://10.1.1.5:9093, CONTROLLER://192.1.1.8:9094 listener.security.protocol.map = INTERNAL:PLAINTEXT, EXTERNAL:SSL, CONTROLLER:SSL control.plane.listener.name = CONTROLLER On startup, the broker will start listening on "192.1.1.8:9094" with security protocol "SSL". On controller side, when it discovers a broker's published endpoints through zookeeper, it will use the control.plane.listener.name to find the endpoint, which it will use to establish connection to the broker. For example, if the broker's published endpoints on zookeeper are : "endpoints" : ["INTERNAL://broker1.example.com:9092","EXTERNAL://broker1.example.com:9093","CONTROLLER://broker1.example.com:9094"] and the controller's config is : listener.security.protocol.map = INTERNAL:PLAINTEXT, EXTERNAL:SSL, CONTROLLER:SSL control.plane.listener.name = CONTROLLER then controller will use "broker1.example.com:9094" with security protocol "SSL" to connect to the broker. If not explicitly configured, the default value will be null and there will be no dedicated endpoints for controller connections. If explicitly configured, the value cannot be the same as the value of inter.broker.listener.name . controller.listener.names Type: string Default: null Importance: high Dynamic update: read-only A comma-separated list of the names of the listeners used by the controller. This is required if running in KRaft mode. When communicating with the controller quorum, the broker will always use the first listener in this list. Note: The ZK-based controller should not set this configuration. controller.quorum.election.backoff.max.ms Type: int Default: 1000 (1 second) Importance: high Dynamic update: read-only Maximum time in milliseconds before starting new elections. This is used in the binary exponential backoff mechanism that helps prevent gridlocked elections. controller.quorum.election.timeout.ms Type: int Default: 1000 (1 second) Importance: high Dynamic update: read-only Maximum time in milliseconds to wait without being able to fetch from the leader before triggering a new election. controller.quorum.fetch.timeout.ms Type: int Default: 2000 (2 seconds) Importance: high Dynamic update: read-only Maximum time without a successful fetch from the current leader before becoming a candidate and triggering an election for voters; Maximum time without receiving fetch from a majority of the quorum before asking around to see if there's a new epoch for leader. controller.quorum.voters Type: list Default: "" Valid Values: non-empty list Importance: high Dynamic update: read-only Map of id/endpoint information for the set of voters in a comma-separated list of {id}@{host}:{port} entries. For example: 1@localhost:9092,2@localhost:9093,3@localhost:9094 . 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. early.start.listeners Type: string Default: null Importance: high Dynamic update: read-only A comma-separated list of listener names which may be started before the authorizer has finished initialization. This is useful when the authorizer is dependent on the cluster itself for bootstrapping, as is the case for the StandardAuthorizer (which stores ACLs in the metadata log.) By default, all listeners included in controller.listener.names will also be early start listeners. A listener should not appear in this list if it accepts external traffic. leader.imbalance.check.interval.seconds Type: long Default: 300 Valid Values: [1,... ] 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: PLAINTEXT://:9092 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. Listener names and port numbers must be unique. 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 A comma-separated list of the directories where the log data is stored. 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 (1 minute) 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 (1 minute) 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. If set to -1, no time limit is applied. 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 (1 gibibyte) 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 (1 minute) 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: 1048588 Valid Values: [0,... ] Importance: high Dynamic update: cluster-wide The largest record batch size allowed by Kafka (after compression if compression is enabled). If this is increased and there are consumers older than 0.10.2, the consumers' fetch size must also be increased so that they can fetch record batches this large. In the latest message format version, records are always grouped into batches for efficiency. In 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. metadata.log.dir Type: string Default: null Importance: high Dynamic update: read-only This configuration determines where we put the metadata log for clusters in KRaft mode. If it is not set, the metadata log is placed in the first log directory from log.dirs. metadata.log.max.record.bytes.between.snapshots Type: long Default: 20971520 Valid Values: [1,... ] Importance: high Dynamic update: read-only This is the maximum number of bytes in the log between the latest snapshot and the high-watermark needed before generating a new snapshot. The default value is 20971520. To generate snapshots based on the time elapsed, see the metadata.log.max.snapshot.interval.ms configuration. The Kafka node will generate a snapshot when either the maximum time interval is reached or the maximum bytes limit is reached. metadata.log.max.snapshot.interval.ms Type: long Default: 3600000 (1 hour) Valid Values: [0,... ] Importance: high Dynamic update: read-only This is the maximum number of milliseconds to wait to generate a snapshot if there are committed records in the log that are not included in the latest snapshot. A value of zero disables time based snapshot generation. The default value is 3600000. To generate snapshots based on the number of metadata bytes, see the metadata.log.max.record.bytes.between.snapshots configuration. The Kafka node will generate a snapshot when either the maximum time interval is reached or the maximum bytes limit is reached. metadata.log.segment.bytes Type: int Default: 1073741824 (1 gibibyte) Valid Values: [12,... ] Importance: high Dynamic update: read-only The maximum size of a single metadata log file. metadata.log.segment.ms Type: long Default: 604800000 (7 days) Importance: high Dynamic update: read-only The maximum time before a new metadata log file is rolled out (in milliseconds). metadata.max.retention.bytes Type: long Default: 104857600 (100 mebibytes) Importance: high Dynamic update: read-only The maximum combined size of the metadata log and snapshots before deleting old snapshots and log files. Since at least one snapshot must exist before any logs can be deleted, this is a soft limit. metadata.max.retention.ms Type: long Default: 604800000 (7 days) Importance: high Dynamic update: read-only The number of milliseconds to keep a metadata log file or snapshot before deleting it. Since at least one snapshot must exist before any logs can be deleted, this is a soft limit. 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. node.id Type: int Default: -1 Importance: high Dynamic update: read-only The node ID associated with the roles this process is playing when process.roles is non-empty. This is required configuration when running in KRaft mode. 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. Noted: each listener (except for controller listener) creates its own thread pool. 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 records from each source broker. The total number of fetchers on each broker is bound by num.replica.fetchers multiplied by the number of brokers in the cluster.Increasing this value can increase the degree of I/O parallelism in the follower and leader broker at the cost of higher CPU and memory utilization. offset.metadata.max.bytes Type: int Default: 4096 (4 kibibytes) 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 (5 seconds) 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 (soft-limit, overridden if records are too large). offsets.retention.check.interval.ms Type: long Default: 600000 (10 minutes) 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 For subscribed consumers, committed offset of a specific partition will be expired and discarded when 1) this retention period has elapsed after the consumer group loses all its consumers (i.e. becomes empty); 2) this retention period has elapsed since the last time an offset is committed for the partition and the group is no longer subscribed to the corresponding topic. For standalone consumers (using manual assignment), offsets will be expired after this retention period has elapsed since the time of last commit. Note that when a group is deleted via the delete-group request, its committed offsets will also be deleted without extra retention period; also when a topic is deleted via the delete-topic request, upon propagated metadata update any group's committed offsets for that topic will also be deleted without extra retention period. 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 (100 mebibytes) 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. process.roles Type: list Default: "" Valid Values: [broker, controller] Importance: high Dynamic update: read-only The roles that this process plays: 'broker', 'controller', or 'broker,controller' if it is both. This configuration is only applicable for clusters in KRaft (Kafka Raft) mode (instead of ZooKeeper). Leave this config undefined or empty for Zookeeper clusters. queued.max.requests Type: int Default: 500 Valid Values: [1,... ] Importance: high Dynamic update: read-only The number of queued requests allowed for data-plane, before blocking the network threads. 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 replica.fetch.wait.max.ms (broker config). replica.fetch.wait.max.ms Type: int Default: 500 Importance: high Dynamic update: read-only The maximum 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 (5 seconds) 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: 30000 (30 seconds) 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 (64 kibibytes) Importance: high Dynamic update: read-only The socket receive buffer for network requests to the leader for replicating data. replica.socket.timeout.ms Type: int Default: 30000 (30 seconds) 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 (30 seconds) 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. sasl.mechanism.controller.protocol Type: string Default: GSSAPI Importance: high Dynamic update: read-only SASL mechanism used for communication with controllers. Default is GSSAPI. socket.receive.buffer.bytes Type: int Default: 102400 (100 kibibytes) Importance: high Dynamic update: read-only The SO_RCVBUF buffer of the socket server sockets. If the value is -1, the OS default will be used. socket.request.max.bytes Type: int Default: 104857600 (100 mebibytes) 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 (100 kibibytes) Importance: high Dynamic update: read-only The SO_SNDBUF buffer of the socket server sockets. If the value is -1, the OS default will be used. transaction.max.timeout.ms Type: int Default: 900000 (15 minutes) 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 (soft-limit, overridden if records are too large). 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 (100 mebibytes) 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 (7 days) Valid Values: [1,... ] Importance: high Dynamic update: read-only The time in ms that the transaction coordinator will wait without receiving any transaction status updates for the current transaction before expiring its transactional id. Transactional IDs will not expire while a the transaction is still ongoing. 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.connect Type: string Default: null Importance: high Dynamic update: read-only Specifies the ZooKeeper connection string in the form hostname:port where host and port are the host and port of a ZooKeeper server. To allow connecting through other ZooKeeper nodes when that ZooKeeper machine is down you can also specify multiple hosts in the form hostname1:port1,hostname2:port2,hostname3:port3 . The server can also have a ZooKeeper chroot path as part of its ZooKeeper connection string which puts its data under some path in the global ZooKeeper namespace. For example to give a chroot path of /chroot/path you would give the connection string as hostname1:port1,hostname2:port2,hostname3:port3/chroot/path . 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.metadata.migration.enable Type: boolean Default: false Importance: high Dynamic update: read-only Enable ZK to KRaft migration. zookeeper.session.timeout.ms Type: int Default: 18000 (18 seconds) 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.heartbeat.interval.ms Type: int Default: 2000 (2 seconds) Importance: medium Dynamic update: read-only The length of time in milliseconds between broker heartbeats. Used when running in KRaft mode. 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 . broker.session.timeout.ms Type: int Default: 9000 (9 seconds) Importance: medium Dynamic update: read-only The length of time in milliseconds that a broker lease lasts if no heartbeats are made. Used when running in KRaft mode. connections.max.idle.ms Type: long Default: 600000 (10 minutes) Importance: medium Dynamic update: read-only Idle connections timeout: the server socket processor threads close the connections that idle more than this. connections.max.reauth.ms Type: long Default: 0 Importance: medium Dynamic update: read-only When explicitly set to a positive number (the default is 0, not a positive number), a session lifetime that will not exceed the configured value will be communicated to v2.2.0 or later clients when they authenticate. The broker will disconnect any such connection that is not re-authenticated within the session lifetime and that is then subsequently used for any purpose other than re-authentication. Configuration names can optionally be prefixed with listener prefix and SASL mechanism name in lower-case. For example, listener.name.sasl_ssl.oauthbearer.connections.max.reauth.ms=3600000. 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 (5 seconds) Importance: medium Dynamic update: read-only Before each retry, the system needs time to recover from the state that caused the failure (Controller fail over, replica lag etc). This config determines the amount of time to wait before retrying. controller.quorum.append.linger.ms Type: int Default: 25 Importance: medium Dynamic update: read-only The duration in milliseconds that the leader will wait for writes to accumulate before flushing them to disk. controller.quorum.request.timeout.ms Type: int Default: 2000 (2 seconds) Importance: medium 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. controller.socket.timeout.ms Type: int Default: 30000 (30 seconds) 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 The default replication factors for automatically created topics. delegation.token.expiry.time.ms Type: long Default: 86400000 (1 day) Valid Values: [1,... ] Importance: medium Dynamic update: read-only The token validity time in miliseconds 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 DEPRECATED: An alias for delegation.token.secret.key, which should be used instead of this config. delegation.token.max.lifetime.ms Type: long Default: 604800000 (7 days) 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. delegation.token.secret.key Type: password Default: null Importance: medium Dynamic update: read-only Secret key to generate and verify delegation tokens. The 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. 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.max.bytes Type: int Default: 57671680 (55 mebibytes) Valid Values: [1024,... ] Importance: medium Dynamic update: read-only The maximum number of bytes we will return for a fetch request. Must be at least 1024. 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 (3 seconds) 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: 1800000 (30 minutes) 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.max.size Type: int Default: 2147483647 Valid Values: [1,... ] Importance: medium Dynamic update: read-only The maximum number of consumers that a single consumer group can accommodate. group.min.session.timeout.ms Type: int Default: 6000 (6 seconds) 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. initial.broker.registration.timeout.ms Type: int Default: 60000 (1 minute) Importance: medium Dynamic update: read-only When initially registering with the controller quorum, the number of milliseconds to wait before declaring failure and exiting the broker process. 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: 3.5-IV2 Valid Values: [0.8.0, 0.8.1, 0.8.2, 0.9.0, 0.10.0-IV0, 0.10.0-IV1, 0.10.1-IV0, 0.10.1-IV1, 0.10.1-IV2, 0.10.2-IV0, 0.11.0-IV0, 0.11.0-IV1, 0.11.0-IV2, 1.0-IV0, 1.1-IV0, 2.0-IV0, 2.0-IV1, 2.1-IV0, 2.1-IV1, 2.1-IV2, 2.2-IV0, 2.2-IV1, 2.3-IV0, 2.3-IV1, 2.4-IV0, 2.4-IV1, 2.5-IV0, 2.6-IV0, 2.7-IV0, 2.7-IV1, 2.7-IV2, 2.8-IV0, 2.8-IV1, 3.0-IV0, 3.0-IV1, 3.1-IV0, 3.2-IV0, 3.3-IV0, 3.3-IV1, 3.3-IV2, 3.3-IV3, 3.4-IV0, 3.5-IV0, 3.5-IV1, 3.5-IV2] 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 MetadataVersion for the full list. log.cleaner.backoff.ms Type: long Default: 15000 (15 seconds) 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 (1 day) Valid Values: [0,... ] Importance: medium Dynamic update: cluster-wide The amount of time to retain delete tombstone markers for log compacted topics. This setting also gives a bound on the time in which a consumer must complete a read if they begin from offset 0 to ensure that they get a valid snapshot of the final stage (otherwise delete tombstones may be collected before they complete their scan). 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.max.compaction.lag.ms Type: long Default: 9223372036854775807 Valid Values: [1,... ] Importance: medium Dynamic update: cluster-wide The maximum time a message will remain ineligible for compaction in the log. Only applicable for logs that are being compacted. log.cleaner.min.cleanable.ratio Type: double Default: 0.5 Valid Values: [0,... ,1] Importance: medium Dynamic update: cluster-wide The minimum ratio of dirty log to total log for a log to eligible for cleaning. If the log.cleaner.max.compaction.lag.ms or the log.cleaner.min.compaction.lag.ms configurations are also specified, then the log compactor considers the log eligible for compaction as soon as either: (i) the dirty ratio threshold has been met and the log has had dirty (uncompacted) records for at least the log.cleaner.min.compaction.lag.ms duration, or (ii) if the log has had dirty (uncompacted) records for at most the log.cleaner.max.compaction.lag.ms period. log.cleaner.min.compaction.lag.ms Type: long Default: 0 Valid Values: [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 (4 kibibytes) 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 (10 mebibytes) 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: 3.0-IV1 Valid Values: [0.8.0, 0.8.1, 0.8.2, 0.9.0, 0.10.0-IV0, 0.10.0-IV1, 0.10.1-IV0, 0.10.1-IV1, 0.10.1-IV2, 0.10.2-IV0, 0.11.0-IV0, 0.11.0-IV1, 0.11.0-IV2, 1.0-IV0, 1.1-IV0, 2.0-IV0, 2.0-IV1, 2.1-IV0, 2.1-IV1, 2.1-IV2, 2.2-IV0, 2.2-IV1, 2.3-IV0, 2.3-IV1, 2.4-IV0, 2.4-IV1, 2.5-IV0, 2.6-IV0, 2.7-IV0, 2.7-IV1, 2.7-IV2, 2.8-IV0, 2.8-IV1, 3.0-IV0, 3.0-IV1, 3.1-IV0, 3.2-IV0, 3.3-IV0, 3.3-IV1, 3.3-IV2, 3.3-IV3, 3.4-IV0, 3.5-IV0, 3.5-IV1, 3.5-IV2] 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 MetadataVersion. Some examples are: 0.8.2, 0.9.0.0, 0.10.0, check MetadataVersion 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 Valid Values: [0,... ] 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 (5 minutes) 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.connection.creation.rate Type: int Default: 2147483647 Valid Values: [0,... ] Importance: medium Dynamic update: cluster-wide The maximum connection creation rate we allow in the broker at any time. Listener-level limits may also be configured by prefixing the config name with the listener prefix, for example, listener.name.internal.max.connection.creation.rate .Broker-wide connection rate limit should be configured based on broker capacity while listener limits should be configured based on application requirements. New connections will be throttled if either the listener or the broker limit is reached, with the exception of inter-broker listener. Connections on the inter-broker listener will be throttled only when the listener-level rate limit is reached. max.connections Type: int Default: 2147483647 Valid Values: [0,... ] Importance: medium Dynamic update: cluster-wide The maximum number of connections we allow in the broker at any time. This limit is applied in addition to any per-ip limits configured using max.connections.per.ip. Listener-level limits may also be configured by prefixing the config name with the listener prefix, for example, listener.name.internal.max.connections . Broker-wide limit should be configured based on broker capacity while listener limits should be configured based on application requirements. New connections are blocked if either the listener or broker limit is reached. Connections on the inter-broker listener are permitted even if broker-wide limit is reached. The least recently used connection on another listener will be closed in this case. max.connections.per.ip Type: int Default: 2147483647 Valid Values: [0,... ] Importance: medium Dynamic update: cluster-wide 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. New connections from the ip address are dropped if the limit is reached. max.connections.per.ip.overrides Type: string Default: "" Importance: medium Dynamic update: cluster-wide 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: org.apache.kafka.common.security.authenticator.DefaultKafkaPrincipalBuilder 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. If no principal builder is defined, the default behavior depends on the security protocol in use. For SSL authentication, the principal will be derived using the rules defined by ssl.principal.mapping.rules applied on 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 (1 second) 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 (1 mebibyte) 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 (10 mebibytes) 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). replica.selector.class Type: string Default: null Importance: medium Dynamic update: read-only The fully qualified class name that implements ReplicaSelector. This is used by the broker to find the preferred read replica. By default, we use an implementation that returns the leader. 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 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.oauthbearer.jwks.endpoint.url Type: string Default: null Importance: medium Dynamic update: read-only The OAuth/OIDC provider URL from which the provider's JWKS (JSON Web Key Set) can be retrieved. The URL can be HTTP(S)-based or file-based. If the URL is HTTP(S)-based, the JWKS data will be retrieved from the OAuth/OIDC provider via the configured URL on broker startup. All then-current keys will be cached on the broker for incoming requests. If an authentication request is received for a JWT that includes a "kid" header claim value that isn't yet in the cache, the JWKS endpoint will be queried again on demand. However, the broker polls the URL every sasl.oauthbearer.jwks.endpoint.refresh.ms milliseconds to refresh the cache with any forthcoming keys before any JWT requests that include them are received. If the URL is file-based, the broker will load the JWKS file from a configured location on startup. In the event that the JWT includes a "kid" header value that isn't in the JWKS file, the broker will reject the JWT and authentication will fail. sasl.oauthbearer.token.endpoint.url Type: string Default: null Importance: medium Dynamic update: read-only The URL for the OAuth/OIDC identity provider. If the URL is HTTP(S)-based, it is the issuer's token endpoint URL to which requests will be made to login based on the configuration in sasl.jaas.config. If the URL is file-based, it specifies a file containing an access token (in JWT serialized form) issued by the OAuth/OIDC identity provider to use for authorization. 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. sasl.server.max.receive.size Type: int Default: 524288 Importance: medium Dynamic update: read-only The maximum receive size allowed before and during initial SASL authentication. Default receive size is 512KB. GSSAPI limits requests to 64K, but we allow upto 512KB by default for custom SASL mechanisms. In practice, PLAIN, SCRAM and OAUTH mechanisms can use much smaller limits. security.inter.broker.protocol Type: string Default: PLAINTEXT Valid Values: [PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL] 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. socket.connection.setup.timeout.max.ms Type: long Default: 30000 (30 seconds) Importance: medium Dynamic update: read-only The maximum amount of time the client will wait for the socket connection to be established. The connection setup timeout will increase exponentially for each consecutive connection failure up to this maximum. To avoid connection storms, a randomization factor of 0.2 will be applied to the timeout resulting in a random range between 20% below and 20% above the computed value. socket.connection.setup.timeout.ms Type: long Default: 10000 (10 seconds) Importance: medium Dynamic update: read-only The amount of time the client will wait for the socket connection to be established. If the connection is not built before the timeout elapses, clients will close the socket channel. socket.listen.backlog.size Type: int Default: 50 Valid Values: [1,... ] Importance: medium Dynamic update: read-only The maximum number of pending connections on the socket. In Linux, you may also need to configure somaxconn and tcp_max_syn_backlog kernel parameters accordingly to make the configuration takes effect. 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 required, 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,TLSv1.3 Importance: medium Dynamic update: per-broker The list of protocols enabled for SSL connections. The default is 'TLSv1.2,TLSv1.3' when running with Java 11 or newer, 'TLSv1.2' otherwise. With the default value for Java 11, clients and servers will prefer TLSv1.3 if both support it and fallback to TLSv1.2 otherwise (assuming both support at least TLSv1.2). This default should be fine for most cases. Also see the config documentation for ssl.protocol . ssl.key.password Type: password Default: null Importance: medium Dynamic update: per-broker The password of the private key in the key store file or the PEM key specified in 'ssl.keystore.key'. 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.certificate.chain Type: password Default: null Importance: medium Dynamic update: per-broker Certificate chain in the format specified by 'ssl.keystore.type'. Default SSL engine factory supports only PEM format with a list of X.509 certificates. ssl.keystore.key Type: password Default: null Importance: medium Dynamic update: per-broker Private key in the format specified by 'ssl.keystore.type'. Default SSL engine factory supports only PEM format with PKCS#8 keys. If the key is encrypted, key password must be specified using 'ssl.key.password'. 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. Key store password is not supported for PEM format. 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. The values currently supported by the default ssl.engine.factory.class are [JKS, PKCS12, PEM]. ssl.protocol Type: string Default: TLSv1.3 Importance: medium Dynamic update: per-broker The SSL protocol used to generate the SSLContext. The default is 'TLSv1.3' when running with Java 11 or newer, 'TLSv1.2' otherwise. This value should be fine for most use cases. Allowed values in recent JVMs are 'TLSv1.2' and 'TLSv1.3'. 'TLS', 'TLSv1.1', 'SSL', 'SSLv2' and 'SSLv3' may be supported in older JVMs, but their usage is discouraged due to known security vulnerabilities. With the default value for this config and 'ssl.enabled.protocols', clients will downgrade to 'TLSv1.2' if the server does not support 'TLSv1.3'. If this config is set to 'TLSv1.2', clients will not use 'TLSv1.3' even if it is one of the values in ssl.enabled.protocols and the server only supports 'TLSv1.3'. 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.certificates Type: password Default: null Importance: medium Dynamic update: per-broker Trusted certificates in the format specified by 'ssl.truststore.type'. Default SSL engine factory supports only PEM format with X.509 certificates. 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, trust store file configured will still be used, but integrity checking is disabled. Trust store password is not supported for PEM format. ssl.truststore.type Type: string Default: JKS Importance: medium Dynamic update: per-broker The file format of the trust store file. The values currently supported by the default ssl.engine.factory.class are [JKS, PKCS12, PEM]. zookeeper.clientCnxnSocket Type: string Default: null Importance: medium Dynamic update: read-only Typically set to org.apache.zookeeper.ClientCnxnSocketNetty when using TLS connectivity to ZooKeeper. Overrides any explicit value set via the same-named zookeeper.clientCnxnSocket system property. zookeeper.ssl.client.enable Type: boolean Default: false Importance: medium Dynamic update: read-only Set client to use TLS when connecting to ZooKeeper. An explicit value overrides any value set via the zookeeper.client.secure system property (note the different name). Defaults to false if neither is set; when true, zookeeper.clientCnxnSocket must be set (typically to org.apache.zookeeper.ClientCnxnSocketNetty ); other values to set may include zookeeper.ssl.cipher.suites , zookeeper.ssl.crl.enable , zookeeper.ssl.enabled.protocols , zookeeper.ssl.endpoint.identification.algorithm , zookeeper.ssl.keystore.location , zookeeper.ssl.keystore.password , zookeeper.ssl.keystore.type , zookeeper.ssl.ocsp.enable , zookeeper.ssl.protocol , zookeeper.ssl.truststore.location , zookeeper.ssl.truststore.password , zookeeper.ssl.truststore.type . zookeeper.ssl.keystore.location Type: string Default: null Importance: medium Dynamic update: read-only Keystore location when using a client-side certificate with TLS connectivity to ZooKeeper. Overrides any explicit value set via the zookeeper.ssl.keyStore.location system property (note the camelCase). zookeeper.ssl.keystore.password Type: password Default: null Importance: medium Dynamic update: read-only Keystore password when using a client-side certificate with TLS connectivity to ZooKeeper. Overrides any explicit value set via the zookeeper.ssl.keyStore.password system property (note the camelCase). Note that ZooKeeper does not support a key password different from the keystore password, so be sure to set the key password in the keystore to be identical to the keystore password; otherwise the connection attempt to Zookeeper will fail. zookeeper.ssl.keystore.type Type: string Default: null Importance: medium Dynamic update: read-only Keystore type when using a client-side certificate with TLS connectivity to ZooKeeper. Overrides any explicit value set via the zookeeper.ssl.keyStore.type system property (note the camelCase). The default value of null means the type will be auto-detected based on the filename extension of the keystore. zookeeper.ssl.truststore.location Type: string Default: null Importance: medium Dynamic update: read-only Truststore location when using TLS connectivity to ZooKeeper. Overrides any explicit value set via the zookeeper.ssl.trustStore.location system property (note the camelCase). zookeeper.ssl.truststore.password Type: password Default: null Importance: medium Dynamic update: read-only Truststore password when using TLS connectivity to ZooKeeper. Overrides any explicit value set via the zookeeper.ssl.trustStore.password system property (note the camelCase). zookeeper.ssl.truststore.type Type: string Default: null Importance: medium Dynamic update: read-only Truststore type when using TLS connectivity to ZooKeeper. Overrides any explicit value set via the zookeeper.ssl.trustStore.type system property (note the camelCase). The default value of null means the type will be auto-detected based on the filename extension of the truststore. 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: "" Valid Values: non-null string Importance: low Dynamic update: read-only The fully qualified name of a class that implements org.apache.kafka.server.authorizer.Authorizer interface, which is used by the broker for authorization. auto.include.jmx.reporter Type: boolean Default: true Importance: low Dynamic update: read-only Deprecated. Whether to automatically include JmxReporter even if it's not listed in metric.reporters . This configuration will be removed in Kafka 4.0, users should instead include org.apache.kafka.common.metrics.JmxReporter in metric.reporters in order to enable the JmxReporter. 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, the <user> and <client-id> quotas that are 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. connection.failed.authentication.delay.ms Type: int Default: 100 Valid Values: [0,... ] Importance: low Dynamic update: read-only Connection close delay on failed authentication: this is the time (in milliseconds) by which connection close will be delayed on authentication failure. This must be configured to be less than connections.max.idle.ms to prevent connection timeout. controller.quorum.retry.backoff.ms Type: int Default: 20 Importance: low Dynamic update: read-only 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. controller.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 controller mutation quotas. controller.quota.window.size.seconds Type: int Default: 1 Valid Values: [1,... ] Importance: low Dynamic update: read-only The time span of each sample for controller mutations quotas. 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 (1 hour) Valid Values: [1,... ] Importance: low Dynamic update: read-only Scan interval to remove expired delegation tokens. kafka.metrics.polling.interval.secs Type: int Default: 10 Valid Values: [1,... ] Importance: low Dynamic update: read-only The metrics polling interval (in seconds) which can be used in kafka.metrics.reporters implementations. kafka.metrics.reporters Type: list Default: "" Importance: low Dynamic update: read-only A list of classes to use as Yammer metrics custom reporters. The reporters should implement kafka.metrics.KafkaMetricsReporter trait. If a client wants to expose JMX operations on a custom reporter, the custom reporter needs to additionally implement an MBean trait that extends kafka.metrics.KafkaMetricsReporterMBean trait so that the registered MBean is compliant with the standard MBean convention. 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 ). Note that in KRaft a default mapping from the listener names defined by controller.listener.names to PLAINTEXT is assumed if no explicit mapping is provided and no other security protocol is in use. 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. metadata.max.idle.interval.ms Type: int Default: 500 Valid Values: [0,... ] Importance: low Dynamic update: read-only This configuration controls how often the active controller should write no-op records to the metadata partition. If the value is 0, no-op records are not appended to the metadata partition. The default value is 500. 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 (30 seconds) 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. producer.id.expiration.ms Type: int Default: 86400000 (1 day) Valid Values: [1,... ] Importance: low Dynamic update: cluster-wide The time in ms that a topic partition leader will wait before expiring producer IDs. Producer IDs will not expire while a transaction associated to them is still ongoing. Note that producer IDs may expire sooner if the last write from the producer ID is deleted due to the topic's retention settings. Setting this value the same or higher than delivery.timeout.ms can help prevent expiration during retries and protect against message duplication, but the default should be reasonable for most use cases. 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. sasl.login.connect.timeout.ms Type: int Default: null Importance: low Dynamic update: read-only The (optional) value in milliseconds for the external authentication provider connection timeout. Currently applies only to OAUTHBEARER. sasl.login.read.timeout.ms Type: int Default: null Importance: low Dynamic update: read-only The (optional) value in milliseconds for the external authentication provider read timeout. Currently applies only to OAUTHBEARER. sasl.login.retry.backoff.max.ms Type: long Default: 10000 (10 seconds) Importance: low Dynamic update: read-only The (optional) value in milliseconds for the maximum wait between login attempts to the external authentication provider. Login uses an exponential backoff algorithm with an initial wait based on the sasl.login.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.login.retry.backoff.max.ms setting. Currently applies only to OAUTHBEARER. sasl.login.retry.backoff.ms Type: long Default: 100 Importance: low Dynamic update: read-only The (optional) value in milliseconds for the initial wait between login attempts to the external authentication provider. Login uses an exponential backoff algorithm with an initial wait based on the sasl.login.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.login.retry.backoff.max.ms setting. Currently applies only to OAUTHBEARER. sasl.oauthbearer.clock.skew.seconds Type: int Default: 30 Importance: low Dynamic update: read-only The (optional) value in seconds to allow for differences between the time of the OAuth/OIDC identity provider and the broker. sasl.oauthbearer.expected.audience Type: list Default: null Importance: low Dynamic update: read-only The (optional) comma-delimited setting for the broker to use to verify that the JWT was issued for one of the expected audiences. The JWT will be inspected for the standard OAuth "aud" claim and if this value is set, the broker will match the value from JWT's "aud" claim to see if there is an exact match. If there is no match, the broker will reject the JWT and authentication will fail. sasl.oauthbearer.expected.issuer Type: string Default: null Importance: low Dynamic update: read-only The (optional) setting for the broker to use to verify that the JWT was created by the expected issuer. The JWT will be inspected for the standard OAuth "iss" claim and if this value is set, the broker will match it exactly against what is in the JWT's "iss" claim. If there is no match, the broker will reject the JWT and authentication will fail. sasl.oauthbearer.jwks.endpoint.refresh.ms Type: long Default: 3600000 (1 hour) Importance: low Dynamic update: read-only The (optional) value in milliseconds for the broker to wait between refreshing its JWKS (JSON Web Key Set) cache that contains the keys to verify the signature of the JWT. sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms Type: long Default: 10000 (10 seconds) Importance: low Dynamic update: read-only The (optional) value in milliseconds for the maximum wait between attempts to retrieve the JWKS (JSON Web Key Set) from the external authentication provider. JWKS retrieval uses an exponential backoff algorithm with an initial wait based on the sasl.oauthbearer.jwks.endpoint.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms setting. sasl.oauthbearer.jwks.endpoint.retry.backoff.ms Type: long Default: 100 Importance: low Dynamic update: read-only The (optional) value in milliseconds for the initial wait between JWKS (JSON Web Key Set) retrieval attempts from the external authentication provider. JWKS retrieval uses an exponential backoff algorithm with an initial wait based on the sasl.oauthbearer.jwks.endpoint.retry.backoff.ms setting and will double in wait length between attempts up to a maximum wait length specified by the sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms setting. sasl.oauthbearer.scope.claim.name Type: string Default: scope Importance: low Dynamic update: read-only The OAuth claim for the scope is often named "scope", but this (optional) setting can provide a different name to use for the scope included in the JWT payload's claims if the OAuth/OIDC provider uses a different name for that claim. sasl.oauthbearer.sub.claim.name Type: string Default: sub Importance: low Dynamic update: read-only The OAuth claim for the subject is often named "sub", but this (optional) setting can provide a different name to use for the subject included in the JWT payload's claims if the OAuth/OIDC provider uses a different name for that claim. security.providers Type: string Default: null Importance: low Dynamic update: read-only A list of configurable creator classes each returning a provider implementing security algorithms. These classes should implement the org.apache.kafka.common.security.auth.SecurityProviderCreator interface. 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.engine.factory.class Type: class Default: null Importance: low Dynamic update: per-broker The class of type org.apache.kafka.common.security.auth.SslEngineFactory to provide SSLEngine objects. Default value is org.apache.kafka.common.security.ssl.DefaultSslEngineFactory. ssl.principal.mapping.rules Type: string Default: DEFAULT Importance: low Dynamic update: read-only A list of rules for mapping from distinguished name from the client certificate to short name. 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, distinguished name of the X.500 certificate will be the principal. For more details on the format please see security authorization and acls . Note that this configuration is ignored if an extension of KafkaPrincipalBuilder is provided by the principal.builder.class configuration. 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: 10000 (10 seconds) 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 (1 hour) 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.ssl.cipher.suites Type: list Default: null Importance: low Dynamic update: read-only Specifies the enabled cipher suites to be used in ZooKeeper TLS negotiation (csv). Overrides any explicit value set via the zookeeper.ssl.ciphersuites system property (note the single word "ciphersuites"). The default value of null means the list of enabled cipher suites is determined by the Java runtime being used. zookeeper.ssl.crl.enable Type: boolean Default: false Importance: low Dynamic update: read-only Specifies whether to enable Certificate Revocation List in the ZooKeeper TLS protocols. Overrides any explicit value set via the zookeeper.ssl.crl system property (note the shorter name). zookeeper.ssl.enabled.protocols Type: list Default: null Importance: low Dynamic update: read-only Specifies the enabled protocol(s) in ZooKeeper TLS negotiation (csv). Overrides any explicit value set via the zookeeper.ssl.enabledProtocols system property (note the camelCase). The default value of null means the enabled protocol will be the value of the zookeeper.ssl.protocol configuration property. zookeeper.ssl.endpoint.identification.algorithm Type: string Default: HTTPS Importance: low Dynamic update: read-only Specifies whether to enable hostname verification in the ZooKeeper TLS negotiation process, with (case-insensitively) "https" meaning ZooKeeper hostname verification is enabled and an explicit blank value meaning it is disabled (disabling it is only recommended for testing purposes). An explicit value overrides any "true" or "false" value set via the zookeeper.ssl.hostnameVerification system property (note the different name and values; true implies https and false implies blank). zookeeper.ssl.ocsp.enable Type: boolean Default: false Importance: low Dynamic update: read-only Specifies whether to enable Online Certificate Status Protocol in the ZooKeeper TLS protocols. Overrides any explicit value set via the zookeeper.ssl.ocsp system property (note the shorter name). zookeeper.ssl.protocol Type: string Default: TLSv1.2 Importance: low Dynamic update: read-only Specifies the protocol to be used in ZooKeeper TLS negotiation. An explicit value overrides any value set via the same-named zookeeper.ssl.protocol system property.

Commands: