Kafka学习（一）-------- Quickstart

参考官网：http://kafka.apache.org/quickstart

一、下载Kafka

官网下载地址 http://kafka.apache.org/downloads

截至2019年7月8日最新版本为 2.3.0 2.12为编译的scala版本 2.3.0为kafka版本

Scala 2.12 - kafka_2.12-2.3.0.tgz (asc, sha512)

解压

> tar -xzf kafka_2.12-2.3.0.tgz

> cd kafka_2.12-2.3.0

二、启动服务

要先启动zookeeper kafka内置了一个也可以不用

> bin/zookeeper-server-start.sh config/zookeeper.properties

[2013-04-22 15:01:37,495] INFO Reading configuration from: config/zookeeper.properties (org.apache.zookeeper.server.quorum.QuorumPeerConfig)

...

> bin/kafka-server-start.sh config/server.properties

[2013-04-22 15:01:47,028] INFO Verifying properties (kafka.utils.VerifiableProperties)

[2013-04-22 15:01:47,051] INFO Property socket.send.buffer.bytes is overridden to 1048576 (kafka.utils.VerifiableProperties)

...

三、创建topic

replication-factor为1   partitions为1

> bin/kafka-topics.sh --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1 --topic test

查看topic

> bin/kafka-topics.sh --list --bootstrap-server localhost:9092

test

也可以不创建topic 设置自动创建当publish的时候

四、发送消息

用command line client 进行测试一行就是一条消息

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

This is a message

This is another message

五、消费者

command line consumer 可以接收消息

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

This is a message

This is another message

六、设置多broker集群

单broker没有意思我们可以设置三个broker

首先为每个broker 复制配置文件

> cp config/server.properties config/server-1.properties

> cp config/server.properties config/server-2.properties

然后编辑

config/server-1.properties:

    broker.id=1

    listeners=PLAINTEXT://:9093

    log.dirs=/tmp/kafka-logs-1

config/server-2.properties:

    broker.id=2

    listeners=PLAINTEXT://:9094

    log.dirs=/tmp/kafka-logs-2

broker.id是唯一的 cluster中每一个node的名字我们在same machine上所有要设置listeners和log.dirs 以防冲突

建一个topic 一个partitions 三个replication-factor

> bin/kafka-topics.sh --create --bootstrap-server localhost:9092 --replication-factor 3 --partitions 1 --topic my-replicated-topic

用describe看看都是什么情况

> bin/kafka-topics.sh --describe --bootstrap-server localhost:9092 --topic my-replicated-topic

Topic:my-replicated-topic   PartitionCount:1    ReplicationFactor:3 Configs:

    Topic: my-replicated-topic  Partition: 0    Leader: 1   Replicas: 1,2,0 Isr: 1,2,0

有几个概念：
"leader" is the node responsible for all reads and writes for the given partition. Each node will be the leader for a randomly selected portion of the partitions.
"replicas" is the list of nodes that replicate the log for this partition regardless of whether they are the leader or even if they are currently alive.
"isr" is the set of "in-sync" replicas. This is the subset of the replicas list that is currently alive and caught-up to the leader.

刚才那个topic

> bin/kafka-topics.sh --describe --bootstrap-server localhost:9092 --topic test

Topic:test  PartitionCount:1    ReplicationFactor:1 Configs:

    Topic: test Partition: 0    Leader: 0   Replicas: 0 Isr: 0

发送接收

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

...

my test message 1

my test message 2

^C

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

...

my test message 1

my test message 2

^C

试一下容错 fault-tolerance

> ps aux | grep server-1.properties

7564 ttys002    0:15.91 /System/Library/Frameworks/JavaVM.framework/Versions/1.8/Home/bin/java...

> kill -9 7564

看一下变化：Leader换了一个  因为1被干掉了

> bin/kafka-topics.sh --describe --bootstrap-server localhost:9092 --topic my-replicated-topic

Topic:my-replicated-topic   PartitionCount:1    ReplicationFactor:3 Configs:

    Topic: my-replicated-topic  Partition: 0    Leader: 2   Replicas: 1,2,0 Isr: 2,0

还是收到了消息

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

...

my test message 1

my test message 2

^C

七、使用kafka import/export data

刚才都是console 的数据，其他的sources other systems呢用Kafka Connect

弄一个数据

> echo -e "foo\nbar" > test.txt

启动  指定配置文件

> bin/connect-standalone.sh config/connect-standalone.properties config/connect-file-source.properties config/connect-file-sink.properties

验证一下

> more test.sink.txt

foo

bar

消费者端

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

{"schema":{"type":"string","optional":false},"payload":"foo"}

{"schema":{"type":"string","optional":false},"payload":"bar"}

...

可以继续写入

> echo Another line>> test.txt

八、使用Kafka Streams

http://kafka.apache.org/22/documentation/streams/quickstart

WordCountDemo

https://github.com/apache/kafka/blob/2.2/streams/examples/src/main/java/org/apache/kafka/streams/examples/wordcount/WordCountDemo.java

代码片段

// Serializers/deserializers (serde) for String and Long types

final Serde<String> stringSerde = Serdes.String();

final Serde<Long> longSerde = Serdes.Long();

// Construct a `KStream` from the input topic "streams-plaintext-input", where message values

// represent lines of text (for the sake of this example, we ignore whatever may be stored

// in the message keys).

KStream<String, String> textLines = builder.stream("streams-plaintext-input",

    Consumed.with(stringSerde, stringSerde);

KTable<String, Long> wordCounts = textLines

    // Split each text line, by whitespace, into words.

    .flatMapValues(value -> Arrays.asList(value.toLowerCase().split("\\W+")))

    // Group the text words as message keys

    .groupBy((key, value) -> value)

    // Count the occurrences of each word (message key).

    .count()

// Store the running counts as a changelog stream to the output topic.

wordCounts.toStream().to("streams-wordcount-output", Produced.with(Serdes.String(), Serdes.Long()));

建一个 Kafka producer 指定input topic output topic

> bin/kafka-topics.sh --create \

    --bootstrap-server localhost:9092 \

    --replication-factor 1 \

    --partitions 1 \

    --topic streams-wordcount-output \

    --config cleanup.policy=compact

Created topic "streams-wordcount-output".

启动WordCount demo application

bin/kafka-run-class.sh org.apache.kafka.streams.examples.wordcount.WordCountDemo

启动一个生产者写数据

> bin/kafka-console-producer.sh --broker-list localhost:9092 --topic streams-plaintext-input

all streams lead to kafka

hello kafka streams

启动一个消费者接数据

> bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 \

    --topic streams-wordcount-output \

    --from-beginning \

    --formatter kafka.tools.DefaultMessageFormatter \

    --property print.key=true \

    --property print.value=true \

    --property key.deserializer=org.apache.kafka.common.serialization.StringDeserializer \

    --property value.deserializer=org.apache.kafka.common.serialization.LongDeserializer

all     1

streams 1

lead    1

to      1

kafka   1

hello   1

kafka   2

streams 2

kafka   1

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