~/brew/etc/kafka/server.properties

cat /Users/user/brew/etc/kafka/server.properties | grep -v "#" | grep .
broker.id=0
num.network.threads=3
num.io.threads=8
socket.send.buffer.bytes=102400
socket.receive.buffer.bytes=102400
socket.request.max.bytes=104857600
log.dirs=/Users/user/brew/var/lib/kafka-logs
num.partitions=1
num.recovery.threads.per.data.dir=1
offsets.topic.replication.factor=1
transaction.state.log.replication.factor=1
transaction.state.log.min.isr=1
log.retention.hours=168
log.retention.check.interval.ms=300000
zookeeper.connect=localhost:2181
zookeeper.connection.timeout.ms=18000
group.initial.rebalance.delay.ms=0

Full example

/Users/user/brew/etc/kafka/server.properties

 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.
 # The ASF licenses this file to You under the Apache License, Version 2.0
 # (the "License"); you may not use this file except in compliance with
 # the License.  You may obtain a copy of the License at
 #
 #    http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
 #
 # This configuration file is intended for use in ZK-based mode, where Apache ZooKeeper is required.
 # See kafka.server.KafkaConfig for additional details and defaults
 #
 
 ############################# Server Basics #############################
 
 # The id of the broker. This must be set to a unique integer for each broker.
 broker.id=0
 
 ############################# Socket Server Settings #############################
 
 # The address the socket server listens on. If not configured, the host name will be equal to the value of
 # java.net.InetAddress.getCanonicalHostName(), with PLAINTEXT listener name, and port 9092.
 #   FORMAT:
 #     listeners = listener_name://host_name:port
 #   EXAMPLE:
 #     listeners = PLAINTEXT://your.host.name:9092
 #listeners=PLAINTEXT://:9092
 
 # Listener name, hostname and port the broker will advertise to clients.
 # If not set, it uses the value for "listeners".
 #advertised.listeners=PLAINTEXT://your.host.name:9092
 
 # Maps listener names to security protocols, the default is for them to be the same. See the config documentation for more details
 #listener.security.protocol.map=PLAINTEXT:PLAINTEXT,SSL:SSL,SASL_PLAINTEXT:SASL_PLAINTEXT,SASL_SSL:SASL_SSL
 
 # The number of threads that the server uses for receiving requests from the network and sending responses to the network
 num.network.threads=3
 
 # The number of threads that the server uses for processing requests, which may include disk I/O
 num.io.threads=8
 
 # The send buffer (SO_SNDBUF) used by the socket server
 socket.send.buffer.bytes=102400
 
 # The receive buffer (SO_RCVBUF) used by the socket server
 socket.receive.buffer.bytes=102400
 
 # The maximum size of a request that the socket server will accept (protection against OOM)
 socket.request.max.bytes=104857600
 
 
 ############################# Log Basics #############################
 
 # A comma separated list of directories under which to store log files
 log.dirs=/Users/user/brew/var/lib/kafka-logs
 
 # The default number of log partitions per topic. More partitions allow greater
 # parallelism for consumption, but this will also result in more files across
 # the brokers.
 num.partitions=1
 
 # The number of threads per data directory to be used for log recovery at startup and flushing at shutdown.
 # This value is recommended to be increased for installations with data dirs located in RAID array.
 num.recovery.threads.per.data.dir=1
 
 ############################# Internal Topic Settings  #############################
 # The replication factor for the group metadata internal topics "__consumer_offsets" and "__transaction_state"
 # For anything other than development testing, a value greater than 1 is recommended to ensure availability such as 3.
 offsets.topic.replication.factor=1
 transaction.state.log.replication.factor=1
 transaction.state.log.min.isr=1
 
 ############################# Log Flush Policy #############################
 
 # Messages are immediately written to the filesystem but by default we only fsync() to sync
 # the OS cache lazily. The following configurations control the flush of data to disk.
 # There are a few important trade-offs here:
 #    1. Durability: Unflushed data may be lost if you are not using replication.
 #    2. Latency: Very large flush intervals may lead to latency spikes when the flush does occur as there will be a lot of data to flush.
 #    3. Throughput: The flush is generally the most expensive operation, and a small flush interval may lead to excessive seeks.
 # The settings below allow one to configure the flush policy to flush data after a period of time or
 # every N messages (or both). This can be done globally and overridden on a per-topic basis.
 
 # The number of messages to accept before forcing a flush of data to disk
 #log.flush.interval.messages=10000
 
 # The maximum amount of time a message can sit in a log before we force a flush
 #log.flush.interval.ms=1000
 
 ############################# Log Retention Policy #############################
 
 # The following configurations control the disposal of log segments. The policy can
 # be set to delete segments after a period of time, or after a given size has accumulated.
 # A segment will be deleted whenever *either* of these criteria are met. Deletion always happens
 # from the end of the log.
 
 # The minimum age of a log file to be eligible for deletion due to age
 log.retention.hours=168
 
 # A size-based retention policy for logs. Segments are pruned from the log unless the remaining
 # segments drop below log.retention.bytes. Functions independently of log.retention.hours.
 #log.retention.bytes=1073741824
 
 # The maximum size of a log segment file. When this size is reached a new log segment will be created.
 #log.segment.bytes=1073741824
 
 # The interval at which log segments are checked to see if they can be deleted according
 # to the retention policies
 log.retention.check.interval.ms=300000
 
 ############################# Zookeeper #############################
 
 # Zookeeper connection string (see zookeeper docs for details).
 # This is a comma separated host:port pairs, each corresponding to a zk
 # server. e.g. "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002".
 # You can also append an optional chroot string to the urls to specify the
 # root directory for all kafka znodes.
 zookeeper.connect=localhost:2181
 
 # Timeout in ms for connecting to zookeeper
 zookeeper.connection.timeout.ms=18000
 
 
 ############################# Group Coordinator Settings #############################
 
 # The following configuration specifies the time, in milliseconds, that the GroupCoordinator will delay the initial consumer rebalance.
 # The rebalance will be further delayed by the value of group.initial.rebalance.delay.ms as new members join the group, up to a maximum of max.poll.interval.ms.
 # The default value for this is 3 seconds.
 # We override this to 0 here as it makes for a better out-of-the-box experience for development and testing.
 # However, in production environments the default value of 3 seconds is more suitable as this will help to avoid unnecessary, and potentially expensive, rebalances during application startup.
 group.initial.rebalance.delay.ms=0

See also

• kafka-server-start, ~/brew/etc/kafka/server.properties, ~/brew/var/lib/kafka-logs/
• Kafka, kafka-cluster -h, kafka-configs, kafka-features, kafka-topics, kafka-consumer-groups, kafka-storage, kafka-server-start, kafka-server-stop, kafka-reassign-partitions, kafka-topics, kafka-console-producer, Amazon MSK, Kafka Connect, 9092, server.properties, KRaft, Kafka changelog