kafka服务器搭建与测试

kafka服务器搭建

　　kafka自身集群信息的管理以及对producer和consumer的信息管理是通过zookeeper实现的，zookeepr是kafka不可分割的一部分，所以搭建zookeeper服务器是搭建kafka集群环境不可或缺的一部分。zookeeper集群的搭建在网上有很多相关资料，本文不在详细描述，也可参照我自己编写的zookeeper 安装的三种模式搭建zookeeper集群。本文所写的kafka服务搭建方法适用于Ubuntu系统和MacOS系统（亲测）。

　　集群搭建软件环境：

• JDK: java version 1.8.0_121
• zookeeper：zookeeper-3.4.9
• kafka: kafka-2.10-0.10.2.0

　　首先，登录官方网站下载搭建环境所需的压缩包kafka-2.10-0.10.2.0.tgz：

http://kafka.apache.org/downloads

　　然后将该包解压到你需要安装的目录下：

tar -zxvf kafka-2.10-0.10.2.0.tgz

• 单机模型

　　kafka单机模型指的是只在一台服务器上部署一个kafka实例(broker)。首先进入配置文件目录下编写broker配置文件。kafka解压包中的config目录下已经有了一份现成的broker配置文件server.properties，我们将其中的部分内容进行修改已达到自己想要的状态。首先进入config目录下，然后使用vim命令打开server.properties文件：

vim config/server.properties

　　本文主要修改以下参数：

• broker.id  该参数是kafka集群中每一个broker的唯一标识，用int型表示；
• delete.topic.enable: 该选项用来表示对topic进行删除操作时是否立刻生效，如果设置为true则立刻生效。默认该选项被注销；
• host.name: 配置broker的IP地址，即该台服务器的IP地址；
• port：配置该broker与客户端、与其他broker、与zookeeper通信的端口地址；
• log.dirs: 配置broker日志存储地址；
• zookeeper.connect: broker需要向zookeeper注册自己的信息，以便整个集群知道自己的存在；
• zookeeper.connection.timeout.ms:与zookeeper连接时间，如果在该时间内没有与zookeeper连接成功，则该broker就不会被添加到kafka集群中。

　　其他配置参考暂时按照默认数据配置，不做任何更改，修改完成后的配置文件如下（去注释版）：

# The id of the broker. This must be set to a unique integer for each broker.
broker.id=0

# Switch to enable topic deletion or not, default value is false
#delete.topic.enable=true

# Hostname and port the broker will advertise to producers and consumers. If not set

host.name=127.0.0.1
port=9092

# The number of threads handling network requests
num.network.threads=3

# The number of threads doing 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 seperated list of directories under which to store log files
log.dirs=/Users/wangchaohui/DevelopEnvironment/kafka_2.10-0.10.2.0/Data/log

# 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



############################# Log Retention Policy #############################


# 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 as long as the remaining
# segments don't 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=6000

　　至此，kafka单机版环境搭建完成。下面赶快运行尝鲜吧。

　　首先启动zookeeper集群，从配置文件中可以看出，本文只配置了一台zookeeper服务器。首先进入zookeeper的bin目录下，然后执行启动命令：

　　然后启动kafka服务器，kafka服务器启动命令需要添加broker配置文件作为参数：

cd ~/DevelopEnvironment/kafka_2.10-0.10.2.0/bin
./kafka-server-start.sh ../config/server.properties 

　　当看到终端输出“[Kafka Server 0], started (kafka.server.KafkaServer)”等相关信息时，说明kafka集群启动成功。

　　下面我们创建一个topic，该topic名称为“my-first-topic”，对应的partitions和replication都为1，这两个参数的含义请参见kafka基础概念，这里不再详细介绍。在bin目录下执行如下命令：

./kafka-topics.sh --create --zookeeper 127.0.0.1:2181 --topic my-first-topic --partitions 1 --replication-factor 1

　　此时我们看见终端打印出如下信息：Created topic "my-first-topic". 说明我们的topic创建成功。现在可以通过describe参数查看我们创建的topic:

 

　　下面对打印出来的内容做个粗略解释：

• Topic:topic 名称；
• PartitionCount：该topic的partition个数；
• ReplicationFactor：每个partition的冗余个数（包括自身）.

　　接下来的五个参数一起解释：my-first-topic(Topic)只有一个Partition为Partiton 0，所以他的所有备份也就只有一个在broker 0上（Replicas:0），所以partition 0对应的loader也就在broker 0上（Leader:0），当前存储partition 0 有效的broker 只有 broker 0。 

　　下面我们通过kafka自带producer客户端脚本文件向刚创建的topic发送信息：

 ./kafka-console-producer.sh --broker-list 127.0.0.1:9092 --topic my-first-topic
This is test message : 1
This is test message : 2
This is test message : 3

　　然后我们运用kafka自带的consumer客户端脚本文件从broker 0 的 my-first-topic 中获取刚才发送的三条消息，命令如下：

./kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --topic my-first-topic --from-beginning

　　当执行上面命令后终端打印出如下信息：

This is test message : 1
This is test message : 2
This is test message : 3

　　恰好是我们刚刚发送的三条信息，说明以上操作完全成功^_^

　　停止集群命令：

./kafka-server-stop.sh 

• kafka伪集群模型

　　在实际的生产过程中，对kafka的应用一般不会只使用一台服务器，都是通过多台服务器搭建kafka集群环境，这样才能体现出kafka的易扩展性、高吞吐量和安全性。由于本文章只是为了学习使用，而且我也只有一个PC机，没有集群环境，所以我么可以搭建一个kafka伪集群模型来模拟kafka集群模型。

　　前面我们说过，kafka启动命令中需要携带broker配置文件作为参数，而broker也就代表着kafka集群中的每台服务器，所以我们要模拟一个有N台服务器的kafka集群，就需要编写N个broker配置文件。由于是在一个机器上模拟多台broker，所以每个broker的host.name 均相同，但port一定不能一样，否则就会后面启动的broker就会因为端口占用而不会正确启动。

　　下面分别为另外两个broker的配置文件server-1.properties和server-2.properties

　　server-1.properties:

# The id of the broker. This must be set to a unique integer for each broker.
broker.id=1

# Switch to enable topic deletion or not, default value is false
#delete.topic.enable=true



# Hostname and port the broker will advertise to producers and consumers. If not set

host.name=127.0.0.1
port=9093

# The number of threads handling network requests
num.network.threads=3

# The number of threads doing 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 seperated list of directories under which to store log files
log.dirs=/Users/wangchaohui/DevelopEnvironment/kafka_2.10-0.10.2.0/Data/log-1

# 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



############################# Log Retention Policy #############################


# 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 as long as the remaining
# segments don't 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=6000

　　server-2.properties:

# The id of the broker. This must be set to a unique integer for each broker.
broker.id=2

# Switch to enable topic deletion or not, default value is false
#delete.topic.enable=true



# Hostname and port the broker will advertise to producers and consumers. If not set

host.name=127.0.0.1
port=9094

# The number of threads handling network requests
num.network.threads=3

# The number of threads doing 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 seperated list of directories under which to store log files
log.dirs=/Users/wangchaohui/DevelopEnvironment/kafka_2.10-0.10.2.0/Data/log-2

# 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



############################# Log Retention Policy #############################


# 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 as long as the remaining
# segments don't 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=6000

　　需要注意的是三个配置文件不同的地方：

1.  broker.id
2.  port
3.  log.dirs

　　下面分别启动启动三个broker，请确保在启动broker之前zookeeper集群一定是成功运行的状态。启动命令如下：

./kafka-server-start.sh ../config/server.properties
./kafka-server-start.sh ../config/server-1.properties
./kafka-server-start.sh ../config/server-2.properties

　　从三个broker的启动信息当中我们可以看到如下信息：

　　其中的127.0.0.1,9092、127.0.0.1,9093、127.0.0.1,9094说明我们的配置文件起到了作用^_^，并且三个broker都启动成功。

　　下面我们在伪集群中创建新的topic：my-second-topic，并设置partitions为3，replication-factor为2，命令如下：

./kafka-topics.sh --create --zookeeper 127.0.0.1:2181 --topic my-second-topic --partitions 3 --replication-factor 2

　　执行完命令后，终端显示“Created topic "my-second-topic".” 说明topic创建成功啦。

　　同样，我们使用describe命令查看我们创建的topic：

./kafka-topics.sh --describe --zookeeper 127.0.0.1:2181 --topic my-second-topic

　　终端显示如下：

　　各个参数的含义上面已经解释过啦，而且也十分容易看懂，这里就不在重复描述啦。

　　下面我们向my-second-topic 发送新的message：

./kafka-console-producer.sh --broker-list 127.0.0.1:9092 --topic my-second-topic
my new test message 1
my new test message 2
my new test message 3

　　然后，我们从consumer端获取刚才发送的三条新消息：

./kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --topic my-second-topic --from-beginning

　　执行完命令后，我们可以看到终端打印出来了刚才发送的三条消息：

my new test message 1
my new test message 2
my new test message 3

　　此时说明我们搭建的集群已经可以发送和接受消息啦。

　　kafka集群通过replicate方式来保证集群的安全性，哪怕只有一个broker存活，整个kafka集群系统也能正常运行（前提是你需要的topic在存活的那个broker上），那么下面我们就测试一下 集群的抗击打能力。

　　上面我们已经通过describe命令查看了my-second-topic状态，这里我们在重复执行一次，以便与下面做对比，命令不在重复，执行后的结果如下：

　　由于我们刚才向broker 0上发送了消息，所以刚才接受消息的一定是 partition 2。下面我们kill掉broker 0 服务器对应的进程

ps aux | grep server.properties

wangchaohui       3310   1.1  6.9  6279396 1161100 s000  S+    4:24下午   1:03.88 /usr/bin/java -Xmx1G -Xms1G -server -XX:+UseG1GC

　　然后根据进程号杀死该进程：

kill -9 3310

　　执行完成后可以看见broker 1，broker 2 对应的终端打印出如下信息：

java.io.IOException: Connection to 0 was disconnected before the response was read
    at kafka.utils.NetworkClientBlockingOps$$anonfun$blockingSendAndReceive$extension$1$$anonfun$apply$1.apply(NetworkClientBlockingOps.scala:114)
    at kafka.utils.NetworkClientBlockingOps$$anonfun$blockingSendAndReceive$extension$1$$anonfun$apply$1.apply(NetworkClientBlockingOps.scala:112)
    at scala.Option.foreach(Option.scala:236)
    at kafka.utils.NetworkClientBlockingOps$$anonfun$blockingSendAndReceive$extension$1.apply(NetworkClientBlockingOps.scala:112)
    at kafka.utils.NetworkClientBlockingOps$$anonfun$blockingSendAndReceive$extension$1.apply(NetworkClientBlockingOps.scala:108)
    at kafka.utils.NetworkClientBlockingOps$.recursivePoll$1(NetworkClientBlockingOps.scala:136)
    at kafka.utils.NetworkClientBlockingOps$.kafka$utils$NetworkClientBlockingOps$$pollContinuously$extension(NetworkClientBlockingOps.scala:142)
    at kafka.utils.NetworkClientBlockingOps$.blockingSendAndReceive$extension(NetworkClientBlockingOps.scala:108)
    at kafka.server.ReplicaFetcherThread.sendRequest(ReplicaFetcherThread.scala:249)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:234)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:42)
    at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:118)
    at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:103)
    at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:63)
[2017-03-20 17:09:40,278] WARN [ReplicaFetcherThread-0-0], Error in fetch kafka.server.ReplicaFetcherThread$FetchRequest@3e2b9697 (kafka.server.ReplicaFetcherThread)
java.io.IOException: Connection to 127.0.0.1:9092 (id: 0 rack: null) failed
    at kafka.utils.NetworkClientBlockingOps$.awaitReady$1(NetworkClientBlockingOps.scala:84)
    at kafka.utils.NetworkClientBlockingOps$.blockingReady$extension(NetworkClientBlockingOps.scala:94)
    at kafka.server.ReplicaFetcherThread.sendRequest(ReplicaFetcherThread.scala:244)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:234)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:42)
    at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:118)
    at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:103)
    at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:63)
[2017-03-20 17:09:42,288] WARN [ReplicaFetcherThread-0-0], Error in fetch kafka.server.ReplicaFetcherThread$FetchRequest@7ee0ff45 (kafka.server.ReplicaFetcherThread)
java.io.IOException: Connection to 127.0.0.1:9092 (id: 0 rack: null) failed
    at kafka.utils.NetworkClientBlockingOps$.awaitReady$1(NetworkClientBlockingOps.scala:84)
    at kafka.utils.NetworkClientBlockingOps$.blockingReady$extension(NetworkClientBlockingOps.scala:94)
    at kafka.server.ReplicaFetcherThread.sendRequest(ReplicaFetcherThread.scala:244)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:234)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:42)
    at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:118)
    at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:103)
    at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:63)
[2017-03-20 17:09:44,011] INFO Creating /controller (is it secure? false) (kafka.utils.ZKCheckedEphemeral)
[2017-03-20 17:09:44,012] INFO Result of znode creation is: OK (kafka.utils.ZKCheckedEphemeral)
[2017-03-20 17:09:44,012] INFO 1 successfully elected as leader (kafka.server.ZookeeperLeaderElector)
[2017-03-20 17:09:44,292] WARN [ReplicaFetcherThread-0-0], Error in fetch kafka.server.ReplicaFetcherThread$FetchRequest@3f48dc67 (kafka.server.ReplicaFetcherThread)
java.io.IOException: Connection to 127.0.0.1:9092 (id: 0 rack: null) failed
    at kafka.utils.NetworkClientBlockingOps$.awaitReady$1(NetworkClientBlockingOps.scala:84)
    at kafka.utils.NetworkClientBlockingOps$.blockingReady$extension(NetworkClientBlockingOps.scala:94)
    at kafka.server.ReplicaFetcherThread.sendRequest(ReplicaFetcherThread.scala:244)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:234)
    at kafka.server.ReplicaFetcherThread.fetch(ReplicaFetcherThread.scala:42)
    at kafka.server.AbstractFetcherThread.processFetchRequest(AbstractFetcherThread.scala:118)
    at kafka.server.AbstractFetcherThread.doWork(AbstractFetcherThread.scala:103)
    at kafka.utils.ShutdownableThread.run(ShutdownableThread.scala:63)

　　从waring信息可以看到连接broker 0 失败。下面重新执行 topic 命令 describe，查看my-second-topic状态如下：

　　与刚才的topic状态进行对比，发现partition1和partition2都受到了影响，对于partition1 和partition2 ，当前有效的broker只有 2 和 1 了，并且，partition2的leader由原来的0变成了1。

　　那么，我们现在同样向broker0发送message，看看会不会影响客户端发送信息，在刚才的基础上，我们在发送4，5，6三条消息：

./kafka-console-producer.sh --broker-list 127.0.0.1:9092 --topic my-second-topic
my new test message 1
my new test message 2
my new test message 3
my new test message 4
my new test message 5
my new test message 6

　　此时客户端仍然可以成功接受到信息：

wangchahuideMBP:bin wangchaohui$ ./kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --topic my-second-topic --from-beginning
my new test message 1
my new test message 2
my new test message 3
[2017-03-20 17:09:46,804] WARN Auto-commit of offsets {my-second-topic-2=OffsetAndMetadata{offset=1, metadata=''}, my-second-topic-1=OffsetAndMetadata{offset=1, metadata=''}, my-second-topic-0=OffsetAndMetadata{offset=1, metadata=''}} failed for group console-consumer-36818: Offset commit failed with a retriable exception. You should retry committing offsets. (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
my new test message 4
my new test message 5
my new test message 6

 　　那么我们接着kill掉broker 1，看看还能不能发送信息：

ps aux | grep server-1.properties
......
kill -9 3539

　　再次查看my-second-topic状态如下：

　　此时我们发现partition 0的leader由原来的1变成了2，可是我不明白的是为什么partition2的leader还是broker 1 ，而且有效broker 竟然是1......

　　下面继续发送消息7，8，9：

./kafka-console-producer.sh --broker-list 127.0.0.1:9092 --topic my-second-topic
my new test message 1
my new test message 2
my new test message 3
my new test message 4
my new test message 5
my new test message 6
my new test message 7
my new test message 8
my new test message 9

 此时consumer依然接受到消息：

/kafka-console-consumer.sh --bootstrap-server 127.0.0.1:9092 --topic my-second-topic --from-beginning
my new test message 1
my new test message 2
my new test message 3
[2017-03-20 17:09:46,804] WARN Auto-commit of offsets {my-second-topic-2=OffsetAndMetadata{offset=1, metadata=''}, my-second-topic-1=OffsetAndMetadata{offset=1, metadata=''}, my-second-topic-0=OffsetAndMetadata{offset=1, metadata=''}} failed for group console-consumer-36818: Offset commit failed with a retriable exception. You should retry committing offsets. (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
my new test message 4
my new test message 5
my new test message 6
[2017-03-20 17:26:48,011] WARN Auto-commit of offsets {my-second-topic-2=OffsetAndMetadata{offset=2, metadata=''}, my-second-topic-1=OffsetAndMetadata{offset=2, metadata=''}, my-second-topic-0=OffsetAndMetadata{offset=2, metadata=''}} failed for group console-consumer-36818: Offset commit failed with a retriable exception. You should retry committing offsets. (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
[2017-03-20 17:26:53,016] WARN Auto-commit of offsets {my-second-topic-2=OffsetAndMetadata{offset=2, metadata=''}, my-second-topic-1=OffsetAndMetadata{offset=2, metadata=''}, my-second-topic-0=OffsetAndMetadata{offset=2, metadata=''}} failed for group console-consumer-36818: Offset commit failed with a retriable exception. You should retry committing offsets. (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
my new test message 7
my new test message 8
my new test message 9

　　这个实验说明了kafka集群的可靠性。果然只有一个broker存活，客户端不需要修改任何参数依然可以正常发送和接受消息。

参考文献

• kafka官方文档