1.Kafka是什么

Kafka是Apache开源的一款基于zookeeper协调的分布式消息系统，具有高吞吐率、高性能、实时、高可靠等特点，可实时处理流式数据。它最初由LinkedIn公司开发，使用Scala语言编写。 Kafka历经数年的发展，从最初纯粹的消息引擎，到近几年开始在流处理平台生态圈发力，多个组织或公司发布了各种不同特性的产品。常见产品如下： <font color="red">**Apache Kafka** ：最“正统”的Kafka`也是开源版，它是后面其他所有发行版的基础。

- <font color="red">**Apache Kafka** ：最“正统”的`Kafka`也是开源版，它是后面其他所有发行版的基础</font>。
- Cloudera/Hortonworks Kafka ：集成了目前主流的大数据框架，能够帮助用户实现从分布式存储、集群调度、流处理到机器学习、实时数据库等全方位的数据处理。
- Confluent Kafka ：主要提供基于`Kafka`的企业级流处理解决方案。`Apache Kafka`，它现在依然是开发人数最多、版本迭代速度最快的`Kafka`

kafka 架构图

1.1Kafka能干嘛

特点

- 高吞吐量、低延迟：即使是非常普通的硬件Kafka也可以支持每秒数百万的消息，它的延迟最低只有几毫秒- 持久性：支持消息持久化，即使数TB级别的消息也能够保持长时间的稳定性能。- 可靠性：支持数据备份防止丢失- 容错性：支持通过Kafka服务器和消费机集群来分区消息，允许集群中的节点失败（若分区副本数量为n，则允许n-1个节点失败）
- 高并发：单机可支持数千个客户端同时读写，支持在线水平扩展。可无缝对接hadoop、strom、spark等，支持Hadoop并行数据加载，

Kafka下载

kafka官网	https://kafka.apache.org/
kafka下载	https://kafka.apache.org/downloads

2. kakfa 安装

2.1 kafka 解压

tar  -zxvf  kafka_2.12-3.7.0.tgzcd kafka_2.12-3.7.0/

2.2 配置zookeeper.properties

#1.创建一个目录
mkdir zookeeper-data
#3.修改文件路径为：
dataDir=/opt/software/kafka/kafka_2.12-3.7.0/zookeeper-data

完整配置

# 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.
# the directory where the snapshot is stored.
dataDir=/opt/software/kafka/kafka_2.12-3.7.0/zookeeper-data
# the port at which the clients will connect
clientPort=2181
# disable the per-ip limit on the number of connections since this is a non-production config
maxClientCnxns=0
# Disable the adminserver by default to avoid port conflicts.
# Set the port to something non-conflicting if choosing to enable this
admin.enableServer=false
# admin.serverPort=8080

2.3 配置 kafak 的 server.properties

配置kafka_2.12-3.7.0/config下的“server.properties”：
修改log.dirs和zookeeper.connect。前者是日志存放文件夹，后者是zookeeper连接地址（端口和clientPort保持一致）

创建一个目录：
mkdir kafka-logs修改配置：listeners=PLAINTEXT://0.0.0.0:9092# Listener name, hostname and port the broker will advertise to clients.
# If not set, it uses the value for "listeners".
#advertised.listeners=PLAINTEXT://your.host.name:9092
advertised.listeners=PLAINTEXT://ip:9092
ip  为外网ip#日志目录log.dirs=/opt/software/kafka/kafka_2.12-3.7.0/kafka-logs
#zookeeper连接地址
zookeeper.connect=ip:2181ip  为外网ip

2.3.1 全部配置文件

# 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.#
# This configuration file is intended for use in ZK-based mode, where Apache ZooKeeper is required.
# 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. If not configured, the host name will be equal to the value of
# java.net.InetAddress.getCanonicalHostName(), with PLAINTEXT listener name, and port 9092.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092
#listeners=PLAINTEXT://:9092
listeners=PLAINTEXT://0.0.0.0:9092# Listener name, hostname and port the broker will advertise to clients.
# If not set, it uses the value for "listeners".
#advertised.listeners=PLAINTEXT://your.host.name:9092
advertised.listeners=PLAINTEXT://ip: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=/opt/software/kafka/kafka_2.12-3.7.0/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 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=ip:2181# Timeout in ms for connecting to zookeeper
zookeeper.connection.timeout.ms=18000############################# 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

3. 启动

3.1 zookeeper启动

# 后台启动zookeeper，指定启动日志
nohup ./bin/zookeeper-server-start.sh ./config/zookeeper.properties > ./zookeeper-run.log 2>&1 &

3.2 后台启动kafka，指定启动日志

# 后台启动kafka，指定启动日志
nohup ./bin/kafka-server-start.sh ./config/server.properties > ./kafka-run.log 2>&1 &

4.测试使用

4.1 创建主题：

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

4.2 生产消息：

bin/kafka-console-producer.sh --topic test --bootstrap-server localhost:9092

4.3 消费消息

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

5.停止服务

5.1 kafka 停止

bin/kafka-server-stop.sh 

5.2 zookeeper 停止

bin/zookeeper-server-stop.sh