2.kafka单节点broker的安装与启动

下载kafka，http://kafka.apache.org/downloads

kafka下面的文件结构如下：

进入bin目录，启动kafka之前要先启动zookeeper

./zookeeper-server-start.sh ../config/zookeeper.properties   启动zookeeper

显示绑定了2181端口，我们来查看一下

zookeeper启动成功

接下来启动kafka

./kafka-server-start.sh ../config/server.properties， 和启动zookeeper类似

kafka启动成功

创建topic

之前说过，kafka是基于发布订阅的方式。并且生产者要指定这条消息是发送到什么topic上的，而且消费者一般也不会消费所有的消息，需要指定订阅的消息是属于哪个topic。
如果想创建一个名为satori的topic就可以这么写，后面的参数之后会介绍

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

查看satori这个topic，直接将create改成describe

启动一个consumer

./kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic satori --from-beginning

顺带一提，在低版本的kafka中还可以通过 ./kafka-console-consumer.sh --zookeeper localhost:2181 --topic satori，但是已经在0.9.0之后被移除了

启动一个producer

./kafka-console-producer.sh --broker-list localhost:9092 --topic satori

我们再来看看consumer

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以上是通过kafka自带的zookeeper启动的，接下来我们演示如何通过单独的zookeeper启动kafka

先安装zookeeper，http://archive.cloudera.com/cdh5/cdh/5/

然后配置到环境变量里面去，激活一下。

然后还要修改一个配置文件，进入conf目录下。

启动zookeeper，进入bin目录

zkServer.sh则是启动文件

但是提示我们需要加一些参数，我们选一下start

我们还可以使用zkCli.sh连接一下

连接成功，这个比较简单

我们再回过头来看kafka的配置文件

我们来看看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.

# 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. It will get the value returned from
# java.net.InetAddress.getCanonicalHostName() if not configured.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092
#listeners=PLAINTEXT://:9092

# Hostname and port the broker will advertise to producers and consumers. If not set,
# it uses the value for "listeners" if configured.  Otherwise, it will use the value
# returned from java.net.InetAddress.getCanonicalHostName().
#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=/tmp/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 for 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=6000

############################# 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

　　

我们来慢慢看

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

之前说过kafka就相当于一个broker，而且还可以有多个broker，那么为了区分，因此每一个broker都是有一个id的，并且id还必须唯一。

这个就不需要改，直接从零开始的异世界生活就行。

#listeners=PLAINTEXT://:9092

监听的端口

# A comma separated list of directories under which to store log files
log.dirs=/tmp/kafka-logs

这个log.dirs是用来存放kafka的日志文件的，这个也不能用这个路径，重启的时候回废掉的，我们自己指定一个，就在kafka下面建一个目录吧。

# 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

分区的数量，后面介绍，就先让它为1

zookeeper.connect=localhost:2181

zookeeper的地址

配置文件就先到这，我们再来启动kafka。忘记说了我们要把kafka加到环境变量里面去

然后kafka-server-start.sh $KAFKA_HOME/config/server.properties

接下来创建topic

kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic hello_satori

指定一个zookeeper，副本系数是1，我们这就一个节点，分区也是1

创建成功

查看topic

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

显示只有一个topic，就是我们的hello_satori

发送消息

kafka-console-producer.sh --broker-list localhost:9092 --topic hello_satori

我们发送消息是往篮子里面发送，所以需要指定--broker-list,指定topic是往哪个topic里面发送,9092是我们在配置文件中写的监听的端口

接收消息

kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic hello_satori --from-beginning

顺带一提，在低版本的kafka中还可以通过 ./kafka-console-consumer.sh --zookeeper localhost:2181 --topic satori，但是已经在0.9.0之后被移除了

注意这里的--from-beginning，如果带上，那么以前的数据也会被消费

启动成功，等待生产者生产数据