Apache Kafka 入门

Apache Kafka 入门大概分为5篇博客，内容都比较基础，计划包含以下内容：

Kafka的基本配置和运行
Kafka命令详细介绍
Kafka-manager的基本配置和运行
Kafka API 简单用法
Spring Boot 集成Kafka

Kafka支持Linux和WIndows环境，本文运行环境使用Linux（CentOS）。

本篇为第二篇。

Kafka命令行详细介绍

常用的几个命令如下：

kafka-server-start.sh
kafka-console-consumer.sh
kafka-console-producer.sh
kafka-topics.sh

在这几个命令中，第一个仅用于启动Kafka，后两个console常用于测试，用途最多的是最后一个命令，所以下面命令中主要介绍的就是 kafka-topics.sh。

kafka-server-start.sh

用法：> bin/kafka-server-start.sh [-daemon] server.properties [--override property=value]*

这个命令后面可以有多个参数，第一个是可选参数，该参数可以让当前命令以后台服务方式执行，第二个必须是 Kafka 的配置文件。后面还可以有多个--override开头的参数，其中的property可以是Broker Configs中提供的所有参数。这些额外的参数会覆盖配置文件中的设置。

例如下面使用同一个配置文件，通过参数覆盖启动多个Broker。

> bin/kafka-server-start.sh -daemon config/server.properties --override broker.id=0 --override log.dirs=/tmp/kafka-logs-1 --override listeners=PLAINTEXT://:9092 --override advertised.listeners=PLAINTEXT://192.168.16.150:9092> bin/kafka-server-start.sh -daemon config/server.properties --override broker.id=1 --override log.dirs=/tmp/kafka-logs-2 --override listeners=PLAINTEXT://:9093 --override advertised.listeners=PLAINTEXT://192.168.16.150:9093

上面这种用法只是用于演示，真正要启动多个Broker 应该针对不同的 Broker 创建相应的 server.properties 配置。

kafka-console-consumer.sh

这个命令只是简单的将消息输出到标准输出中，该命令支持的参数如下。

option                                   Description
------                                   -----------
--blacklist <String: blacklist>          Blacklist of topics to exclude from    consumption.
--bootstrap-server <String: server to    REQUIRED (unless old consumer is       connect to>                              used): The server to connect to.
--consumer-property <String:             A mechanism to pass user-defined       consumer_prop>                           properties in the form key=value to  the consumer.
--consumer.config <String: config file>  Consumer config properties file. Note  that [consumer-property] takes       precedence over this config.
--csv-reporter-enabled                   If set, the CSV metrics reporter will  be enabled
--delete-consumer-offsets                If specified, the consumer path in     zookeeper is deleted when starting up
--enable-systest-events                  Log lifecycle events of the consumer   in addition to logging consumed      messages. (This is specific for      system tests.)
--formatter <String: class>              The name of a class to use for         formatting kafka messages for        display. (default: kafka.tools.      DefaultMessageFormatter)
--from-beginning                         If the consumer does not already have  an established offset to consume     from, start with the earliest        message present in the log rather    than the latest message.
--key-deserializer <String:                                                     deserializer for key>
--max-messages <Integer: num_messages>   The maximum number of messages to      consume before exiting. If not set,  consumption is continual.
--metrics-dir <String: metrics           If csv-reporter-enable is set, and     directory>                               this parameter isset, the csv        metrics will be outputed here
--new-consumer                           Use the new consumer implementation.   This is the default.
--offset <String: consume offset>        The offset id to consume from (a non-  negative number), or 'earliest'      which means from beginning, or       'latest' which means from end        (default: latest)
--partition <Integer: partition>         The partition to consume from.
--property <String: prop>                The properties to initialize the       message formatter.
--skip-message-on-error                  If there is an error when processing a message, skip it instead of halt.
--timeout-ms <Integer: timeout_ms>       If specified, exit if no message is    available for consumption for the    specified interval.
--topic <String: topic>                  The topic id to consume on.
--value-deserializer <String:                                                   deserializer for values>
--whitelist <String: whitelist>          Whitelist of topics to include for     consumption.
--zookeeper <String: urls>               REQUIRED (only when using old          consumer): The connection string for the zookeeper connection in the form host:port. Multiple URLS can be      given to allow fail-over.

--bootstrap-server 必须指定，通常--topic也要指定查看的主题。如果想要从头查看消息，还可以指定--from-beginning参数。一般使用的命令如下。

> bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test --from-beginning

还可以通过下面的命令指定分区查看：

>> bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test --from-beginning --partition 0

kafka-console-producer.sh

这个命令可以将文件或标准输入的内容发送到Kafka集群。该命令参数如下。

Option                                   Description
------                                   -----------
--batch-size <Integer: size>             Number of messages to send in a single batch if they are not being sent     synchronously. (default: 200)
--broker-list <String: broker-list>      REQUIRED: The broker list string in    the form HOST1:PORT1,HOST2:PORT2.
--compression-codec [String:             The compression codec: either 'none',  compression-codec]                       'gzip', 'snappy', or 'lz4'.If        specified without value, then it     defaults to 'gzip'
--key-serializer <String:                The class name of the message encoder  encoder_class>                           implementation to use for            serializing keys. (default: kafka.   serializer.DefaultEncoder)
--line-reader <String: reader_class>     The class name of the class to use for reading lines from standard in. By   default each line is read as a       separate message. (default: kafka.   tools.                               ConsoleProducer$LineMessageReader)
--max-block-ms <Long: max block on       The max time that the producer will    send>                                    block for during a send request      (default: 60000)
--max-memory-bytes <Long: total memory   The total memory used by the producer  in bytes>                                to buffer records waiting to be sent to the server. (default: 33554432)
--max-partition-memory-bytes <Long:      The buffer size allocated for a        memory in bytes per partition>           partition. When records are received which are smaller than this size the producer will attempt to             optimistically group them together   until this size is reached.          (default: 16384)
--message-send-max-retries <Integer>     Brokers can fail receiving the message for multiple reasons, and being      unavailable transiently is just one  of them. This property specifies the number of retires before the         producer give up and drop this       message. (default: 3)
--metadata-expiry-ms <Long: metadata     The period of time in milliseconds     expiration interval>                     after which we force a refresh of    metadata even if we haven't seen any leadership changes. (default: 300000)
--old-producer                           Use the old producer implementation.
--producer-property <String:             A mechanism to pass user-defined       producer_prop>                           properties in the form key=value to  the producer.
--producer.config <String: config file>  Producer config properties file. Note  that [producer-property] takes       precedence over this config.
--property <String: prop>                A mechanism to pass user-defined       properties in the form key=value to  the message reader. This allows      custom configuration for a user-     defined message reader.
--queue-enqueuetimeout-ms <Integer:      Timeout for event enqueue (default:    queue enqueuetimeout ms>                 2147483647)
--queue-size <Integer: queue_size>       If set and the producer is running in  asynchronous mode, this gives the    maximum amount of  messages will     queue awaiting sufficient batch      size. (default: 10000)
--request-required-acks <String:         The required acks of the producer      request required acks>                   requests (default: 1)
--request-timeout-ms <Integer: request   The ack timeout of the producer        timeout ms>                              requests. Value must be non-negative and non-zero (default: 1500)
--retry-backoff-ms <Integer>             Before each retry, the producer        refreshes the metadata of relevant   topics. Since leader election takes  a bit of time, this property         specifies the amount of time that    the producer waits before refreshing the metadata. (default: 100)
--socket-buffer-size <Integer: size>     The size of the tcp RECV size.         (default: 102400)
--sync                                   If set message send requests to the    brokers are synchronously, one at a  time as they arrive.
--timeout <Integer: timeout_ms>          If set and the producer is running in  asynchronous mode, this gives the    maximum amount of time a message     will queue awaiting sufficient batch size. The value is given in ms.      (default: 1000)
--topic <String: topic>                  REQUIRED: The topic id to produce      messages to.
--value-serializer <String:              The class name of the message encoder  encoder_class>                           implementation to use for            serializing values. (default: kafka. serializer.DefaultEncoder)

其中 --broker-list 和 --topic 是两个必须提供的参数。

常用命令如下。

使用标准输入方式。

> bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test

从文件读取：

> bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test < file-input.txt

kafka-topics.sh

相比上面几个偶尔使用的命令来说，kafka-topics.sh 相对就比较重要。该命令包含以下参数。

Create, delete, describe, or change a topic.
Option                                   Description
------                                   -----------
--alter                                  Alter the number of partitions,        replica assignment, and/or           configuration for the topic.
--config <String: name=value>            A topic configuration override for the topic being created or altered.The   following is a list of valid         configurations:                      cleanup.policy                        compression.type                      delete.retention.ms                   file.delete.delay.ms                  flush.messages                        flush.ms                              follower.replication.throttled.       replicas                             index.interval.bytes                  leader.replication.throttled.replicas max.message.bytes                     message.format.version                message.timestamp.difference.max.ms   message.timestamp.type                min.cleanable.dirty.ratio             min.compaction.lag.ms                 min.insync.replicas                   preallocate                           retention.bytes                       retention.ms                          segment.bytes                         segment.index.bytes                   segment.jitter.ms                     segment.ms                            unclean.leader.election.enable        See the Kafka documentation for full   details on the topic configs.
--create                                 Create a new topic.
--delete                                 Delete a topic
--delete-config <String: name>           A topic configuration override to be   removed for an existing topic (see   the list of configurations under the --config option).
--describe                               List details for the given topics.
--disable-rack-aware                     Disable rack aware replica assignment
--force                                  Suppress console prompts
--help                                   Print usage information.
--if-exists                              if set when altering or deleting       topics, the action will only execute if the topic exists
--if-not-exists                          if set when creating topics, the       action will only execute if the      topic does not already exist
--list                                   List all available topics.
--partitions <Integer: # of partitions>  正在创建或更改主题的分区数（警告：如果为具有密钥的主题   （分区）增加了分区  消息的逻辑或排序将受到影响
--replica-assignment <String:            A list of manual partition-to-broker   broker_id_for_part1_replica1 :           assignments for the topic being      broker_id_for_part1_replica2 ,           created or altered.                  broker_id_for_part2_replica1 :                                                broker_id_for_part2_replica2 , ...>
--replication-factor <Integer:           正在创建的主题中每个分区的复制因子。        replication factor>
--topic <String: topic>                  The topic to be create, alter or       describe. Can also accept a regular  expression except for --create option
--topics-with-overrides                  if set when describing topics, only    show topics that have overridden     configs
--unavailable-partitions                 if set when describing topics, only    show partitions whose leader is not  available
--under-replicated-partitions            if set when describing topics, only    show under replicated partitions
--zookeeper <String: urls>               REQUIRED: The connection string for    the zookeeper connection in the form host:port. Multiple URLS can be      given to allow fail-over.

下面是几种常用的 topic 命令。

描述主题的配置

bin/kafka-configs.sh --zookeeper localhost:2181 --describe --entity-type topics --entity-name test_topic

设置保留时间

# Deprecated way
bin/kafka-topics.sh  --zookeeper localhost:2181 --alter --topic test_topic --config retention.ms=1000# Modern way
bin/kafka-configs.sh --zookeeper localhost:2181 --alter --entity-type topics --entity-name test_topic --add-config retention.ms=1000

如果您需要删除主题中的所有消息，则可以利用保留时间。首先将保留时间设置为非常低（1000 ms），等待几秒钟，然后将保留时间恢复为上一个值。

注意：默认保留时间为24小时（86400000毫秒）。

删除主题

bin/kafka-topics.sh --zookeeper localhost:2181 --delete --topic test_topic

注意：需要在Broker的配置文件server.properties中配置 delete.topic.enable=true 才能删除主题。

主题信息

bin/kafka-topics.sh --describe --zookeeper localhost:2181 --topic test_topic

添加分区

bin/kafka-topics.sh --alter --zookeeper localhost:2181 --topic test_topic --partitions 3

创建主题

bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 3 --topic test_topic

列出主题

bin/kafka-topics.sh --list --zookeeper localhost:2181

topic 相关内容来源：http://ronnieroller.com/kafka/cheat-sheet

命令那么多，怎么记？

Kafka 的命令行工具提供了非常丰富的提示信息，所以只需要记住上面大概的几个用法，知道怎么写就行。当需要用到某个命令时，通过命令提示进行操作。

比如说，如何使用 kafka-configs.sh 查看主题（Topic）的配置？

首先，在命令行中输入bin/kafka-configs.sh，然后或输出下面的命令提示信息。

Add/Remove entity config for a topic, client, user or broker
Option                      Description
------                      -----------
--add-config <String>       Key Value pairs of configs to add. Square brackets can be used to group values which contain commas:'k1=v1,k2=[v1,v2,v2],k3=v3'. The following is a  list of valid configurations: For entity_type    'topics':                                        cleanup.policy                                    compression.type                                  delete.retention.ms                               file.delete.delay.ms                              flush.messages                                    flush.ms                                          follower.replication.throttled.replicas           index.interval.bytes                              leader.replication.throttled.replicas             max.message.bytes                                 message.format.version                            message.timestamp.difference.max.ms               message.timestamp.type                            min.cleanable.dirty.ratio                         min.compaction.lag.ms                             min.insync.replicas                               preallocate                                       retention.bytes                                   retention.ms                                      segment.bytes                                     segment.index.bytes                               segment.jitter.ms                                 segment.ms                                        unclean.leader.election.enable                    For entity_type 'brokers':                         follower.replication.throttled.rate               leader.replication.throttled.rate                 For entity_type 'users':                           producer_byte_rate                                SCRAM-SHA-256                                     SCRAM-SHA-512                                     consumer_byte_rate                                For entity_type 'clients':                         producer_byte_rate                                consumer_byte_rate                                Entity types 'users' and 'clients' may be specifiedtogether to update config for clients of a       specific user.
--alter                     Alter the configuration for the entity.
--delete-config <String>    config keys to remove 'k1,k2'
--describe                  List configs for the given entity.
--entity-default            Default entity name for clients/users (applies to  corresponding entity type in command line)
--entity-name <String>      Name of entity (topic name/client id/user principalname/broker id)
--entity-type <String>      Type of entity (topics/clients/users/brokers)
--force                     Suppress console prompts
--help                      Print usage information.
--zookeeper <String: urls>  REQUIRED: The connection string for the zookeeper  connection in the form host:port. Multiple URLS  can be given to allow fail-over.

从第一行可以看到这个命令可以修改 topic, client, user 或 broker 的配置。

如果要设置 topic，就需要设置 entity-type 为topics，输入如下命令：

> bin/kafka-configs.sh --entity-type topics
Command must include exactly one action: --describe, --alter

命令提示需要指定一个操作（不只是上面提示的两个操作），增加--describe试试：

> bin/kafka-configs.sh --entity-type topics --describe
[root@localhost kafka_2.11-0.10.2.1]# bin/kafka-configs.sh --entity-type topics --describe
Missing required argument "[zookeeper]"

继续增加 --zookeeper：

> bin/kafka-configs.sh --entity-type topics --describe --zookeeper localhost:2181
Configs for topic '__consumer_offsets' are segment.bytes=104857600,cleanup.policy=compact,compression.type=producer

由于没有指定主题名，这里显示了__consumer_offsets的信息。下面指定一个topic试试。

> bin/kafka-configs.sh --entity-type topics --describe --zookeeper localhost:2181 --entity-name test
Configs for topic 'test' are

此时显示了test主题的信息，这里是空。

因为Kafka完善的命令提示，可以很轻松的通过提示信息来进行下一步操作，运用熟练后，基本上很快就能实现自己想要的命令。