kafka
(1)kafka是一个分布式的消息缓存系统
(2)kafka集群中的服务器都叫做broker
(3)kafka有两类客户端,一个叫做producer(消息生产者),一类叫做consumer(消息消费者),客户端和broker服务器之间采用TCP协议连接
(4)kafka中的消息可以通过topic进行区分,而且每一个消息topic都会被分区,以分担消息服务器的负载
(5)每一个分区都可以有多个副本,以防止数据的丢失
(6)某一个分区中的数据如果需要更新,都必须通知该分区所有副本中的leader来更新
(7)消费者可以分组,比如有两个消费者组A和B,共同消费一个topic:order_info,A和B所消费的消息不会重复,如order_info中有100个消息,每个消息都有一个id,编号从1-99,那么如果A组消费从0-49,B组消费就从50-99,当然不一定都是连续的
(8)消费者在具体消费某个topic中的消息时,可以制定起始偏移量

集群安装
官网教程
http://kafka.apache.org/22/documentation.html#introduction
1.解压
2.修改server.properties
broker.id=1
zookeeper.connect=hadoop01:2182,hadoop02:2182,hadoop03:2182
3.将zookeeper集群启动
4.在每一台节点上启动broker
bin/kafka-server-start.sh config/server.properties
#5.自带zookeeper,用于单节点,一般集群不用
#bin/zookeeper-server-start.sh config/zookeeper.proterties

开始安装
1.下载解压

[linyouyi@hadoop01 software]$ wget https://mirrors.aliyun.com/apache/kafka/2.2.0/kafka_2.11-2.2.0.tgz
[linyouyi@hadoop01 software]$ tar -zxvf kafka_2.11-2.2.0.tgz -C /hadoop/module/

2.修改配置文件

[linyouyi@hadoop01 software]$ cd /hadoop/module/
[linyouyi@hadoop01 module]$ ll
total 24
drwxrwxr-x 18 linyouyi linyouyi 4096 Aug 12 21:24 apache-storm-2.0.0
drwxr-xr-x 12 linyouyi linyouyi 4096 Aug  9 22:51 hadoop-2.7.7
drwxrwxr-x  7 linyouyi linyouyi 4096 Aug 11 12:10 hbase-2.0.5
drwxr-xr-x  7 linyouyi linyouyi 4096 Jul 22  2017 jdk1.8.0_144
drwxr-xr-x  6 linyouyi linyouyi 4096 Mar 10 03:47 kafka_2.11-2.2.0
drwxr-xr-x 15 linyouyi linyouyi 4096 Aug  8 11:03 zookeeper-3.4.14
[linyouyi@hadoop01 kafka_2.11-2.2.0]$ vim config/server.properties
broker.id=1
log.dirs=/hadoop/kafka_2.11-2.2.0/log/kafka-logs
zookeeper.connect=hadoop01:2182,hadoop02:2182,hadoop03:2182

3.拷贝到其他节点

[linyouyi@hadoop01 kafka_2.11-2.2.0]$ cd ../
[linyouyi@hadoop01 module]$ scp -r kafka_2.11-2.2.0/ linyouyi@hadoop02:/hadoop/module/
[linyouyi@hadoop01 module]$ scp -r kafka_2.11-2.2.0/ linyouyi@hadoop03:/hadoop/module/

4.修改另外两台的broker.id

[linyouyi@hadoop02 kafka_2.11-2.2.0]$ vim config/server.properties 
broker.id=2
[linyouyi@hadoop03 kafka_2.11-2.2.0]$ vim config/server.properties
broker.id=3

5.启动kafka

[linyouyi@hadoop01 kafka_2.11-2.2.0]$ bin/kafka-server-start.sh -deamon config/server.properties
[linyouyi@hadoop01 kafka_2.11-2.2.0]$ jps
109904 Jps
44057 QuorumPeerMain
109503 Kafka
[linyouyi@hadoop02 kafka_2.11-2.2.0]$ bin/kafka-server-start.sh -deamon config/server.properties
[linyouyi@hadoop02 kafka_2.11-2.2.0]$ jps
21308 Jps
20925 Kafka
34879 QuorumPeerMain
[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-server-start.sh -deamon config/server.properties
[linyouyi@hadoop03 kafka_2.11-2.2.0]$ jps
119587 QuorumPeerMain
37651 Jps
37269 Kafka

使用
1.创建话题
//hadoop01:9092,hadoop02:9092,hadoop03:9092都行

[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --create --bootstrap-server hadoop01:9092 --replication-factor 3 --partitions 1 --topic linyouyi
[2019-08-17 15:30:34,616] INFO [ReplicaFetcherManager on broker 3] Removed fetcher for partitions Set(linyouyi-0) (kafka.server.ReplicaFetcherManager)
[2019-08-17 15:30:34,649] INFO [Log partition=linyouyi-0, dir=/tmp/kafka-logs] Loading producer state till offset 0 with message format version 2 (kafka.log.Log)
[2019-08-17 15:30:34,653] INFO [Log partition=linyouyi-0, dir=/tmp/kafka-logs] Completed load of log with 1 segments, log start offset 0 and log end offset 0 in 25 ms (kafka.log.Log)
[2019-08-17 15:30:34,655] INFO Created log for partition linyouyi-0 in /tmp/kafka-logs with properties {compression.type -> producer, message.format.version -> 2.2-IV1, file.delete.delay.ms -> 60000, max.message.bytes -> 1000012, min.compaction.lag.ms -> 0, message.timestamp.type -> CreateTime, message.downconversion.enable -> true, min.insync.replicas -> 1, segment.jitter.ms -> 0, preallocate -> false, min.cleanable.dirty.ratio -> 0.5, index.interval.bytes -> 4096, unclean.leader.election.enable -> false, retention.bytes -> -1, delete.retention.ms -> 86400000, cleanup.policy -> [delete], flush.ms -> 9223372036854775807, segment.ms -> 604800000, segment.bytes -> 1073741824, retention.ms -> 604800000, message.timestamp.difference.max.ms -> 9223372036854775807, segment.index.bytes -> 10485760, flush.messages -> 9223372036854775807}. (kafka.log.LogManager)
[2019-08-17 15:30:34,656] INFO [Partition linyouyi-0 broker=3] No checkpointed highwatermark is found for partition linyouyi-0 (kafka.cluster.Partition)
[2019-08-17 15:30:34,658] INFO Replica loaded for partition linyouyi-0 with initial high watermark 0 (kafka.cluster.Replica)
[2019-08-17 15:30:34,658] INFO Replica loaded for partition linyouyi-0 with initial high watermark 0 (kafka.cluster.Replica)
[2019-08-17 15:30:34,658] INFO Replica loaded for partition linyouyi-0 with initial high watermark 0 (kafka.cluster.Replica)
[2019-08-17 15:30:34,660] INFO [Partition linyouyi-0 broker=3] linyouyi-0 starts at Leader Epoch 0 from offset 0. Previous Leader Epoch was: -1 (kafka.cluster.Partition)


[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --list --bootstrap-server localhost:9092
linyouyi
[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --list --bootstrap-server hadoop01:9092
linyouyi
[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --list --zookeeper hadoop01:2181
linyouyi
[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --create --bootstrap-server hadoop01:9092 --replication-factor 3 --partitions 1 --topic youyi
[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --list --zookeeper hadoop01:2181
linyouyi
youyi

2.生产者往话题里面写消息

[linyouyi@hadoop03 kafka_2.11-2.2.0]$ bin/kafka-console-producer.sh --broker-list localhost:9092 --topic linyouyi>This is a message
>This is another message

3.消费者立马消费消息

[linyouyi@hadoop02 kafka_2.11-2.2.0]$ bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic linyouyi --from-beginning
This is a message
This is another message

4.接着在生产者继续写话题,消费者立马就消费了

5.查看topic linyouyi总体情况

[linyouyi@hadoop01 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --describe --bootstrap-server localhost:9092 --topic linyouyi
Topic:linyouyi    PartitionCount:1    ReplicationFactor:3    Configs:segment.bytes=1073741824
    Topic: linyouyi    Partition: 0    Leader: 3    Replicas: 3,1,2    Isr: 3,1,2

[linyouyi@hadoop01 kafka_2.11-2.2.0]$ bin/kafka-topics.sh --describe --bootstrap-server localhost:9092 --topic youyi
Topic:youyi    PartitionCount:1    ReplicationFactor:3    Configs:segment.bytes=1073741824
    Topic: youyi    Partition: 0    Leader: 3    Replicas: 3,1,2    Isr: 3,1,2