[Java知识库] springboot+redis主从复制、哨兵、读写分离

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-> Java知识库 -> springboot+redis主从复制、哨兵、读写分离 -> 正文阅读

[Java知识库]springboot+redis主从复制、哨兵、读写分离

一、redis安装

# 安装包存放目录
cd /opt/software/
# 下载最新稳定版
wget https://download.redis.io/releases/redis-6.2.6.tar.gz
# 解压
tar -zxvf redis-6.2.6.tar.gz
# 进入解压后的目录
cd /opt/software/redis-6.2.6/
# 编译
make
# 执行 "make install" 默认会安装到 /usr/local/bin，可通过PREFIX指定安装路径
make install PREFIX=/usr/local/redis
# 测试是否安装成功，执行下面命令
/usr/local/redis/bin/redis-server

二、主从及哨兵配置

三个redis实例都运行在192.168.162.10服务器上，端口分别是7001、7002、7003，默认启动时已7001作为主节点，7002与7003作为从节点，下面是主从与哨兵的配置文件需要修改的地方。

1、redis配置

原始配置文件可在解压后的源码文件根目录中找到，这里以从节点 7002 配置文件为例，其余两个配置文件几乎一致。首先将配置文件拷贝到/opt/software/redis-cluster/redis-7002.conf，然后进行下面的修改。

# （1）设置允许外部ip访问，需要注释掉bind配置，并关掉保护模式
# bind 127.0.0.1 -::1
protected-mode no

# （2）修改端口号
port 7002

# （3）修改为以守护进程模式后台运行
daemonize yes

# （4）修改pid文件名，以守护进程运行的时候，会产生pid文件，默认位置为 /run/redis.pid 
# 因为这里在同一台机器上运行多个实例，所以需要指定
pidfile /opt/software/redis-cluster/redis_7002.pid

# （5）修改日志文件位置
logfile /opt/software/redis-cluster/redis_7002.log

# （6）修改rdb快照文件位置
dir /opt/software/redis-cluster
dbfilename dump_7002.rdb

# （7）修改主节点地址，在部分旧版本中是slaveof命令，主节点7001配置文件中不要加这一行
replicaof 192.168.162.10 7001

# （8）aof可按需要开启
appendonly yes
appendfilename appendonly_7002.aof

在上面的配置中，7001文件与7003一致，改一下其中的端口及地址就可以了，其中，7001作为主节点，没有第（7）点。建议三个实例运行在不同的文件夹下，我为了省去切换文件目录的时间，都放在一个文件夹下了。

配置完成后，按三个端口号的顺序启动分别启动三个实例。

/usr/local/redis/bin/redis-server /opt/software/redis-cluster/redis-7001.conf
/usr/local/redis/bin/redis-server /opt/software/redis-cluster/redis-7002.conf
/usr/local/redis/bin/redis-server /opt/software/redis-cluster/redis-7003.conf

启动后，产生的文件如下所示

进入主节点，查看实例主从状况

进入从节点，查看实例主从状况

测试主从复制，在主节点中添加一个缓存，然后从节点中查询

至此，主从复制基本上差不多了，接下来就是哨兵的配置了。

2、sentinel配置

共计启动三个实例，分别运行于27001、27002、27003三个端口，以sentinel-27001.conf为例，配置信息如下，其余两个配置文件基本上一致，改一下端口以及pidfile、logfile即可。

port 27001
daemonize yes
pidfile /opt/software/redis-cluster/sentinel-27001.pid
logfile /opt/software/redis-cluster/sentinel-27001.log

# 监控192.168.162.10:7001实例，实例取名为mymaster，当有两个哨兵认为实例下线后，自动进行故障转移
sentinel monitor mymaster 192.168.162.10 7001 2
# 服务不可达时间，心跳超过这个时间，sentinel将认为节点挂了
sentinel down-after-milliseconds mymaster 5000
sentinel failover-timeout mymaster 60000
sentinel parallel-syncs mymaster 1

分别启动三个哨兵实例

随意连接一个哨兵，查看哨兵监控信息

查看哨兵日志

关闭主节点，再看哨兵日志

从上面的日志文件中，我们可以看到哨兵投票选举leader以及切换主节点的大概过程，这时候，主节点已经切换到7003节点了。

这时候，再重新启动7001节点，也就是之前的主节点，这个节点会被哨兵自动加入到集群中作为从节点，sentinel会打印如下日志

+convert-to-slave slave 192.168.162.10:7001 192.168.162.10 7001 @ mymaster 192.168.162.10 7003

至此，哨兵集群也OK了。接下来就是springboot中配置哨兵集群了。

三、springboot配置哨兵集群及读写分离

创建springboot测试项目，pom.xml如下所示

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.6.3</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>sentinel-cluster</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>spring-boot-sentinel-cluster</name>
	<description>spring-boot-sentinel-cluster</description>
	<properties>
		<java.version>1.8</java.version>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-redis</artifactId>
		</dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-json</artifactId>
        </dependency>

		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<excludes>
						<exclude>
							<groupId>org.projectlombok</groupId>
							<artifactId>lombok</artifactId>
						</exclude>
					</excludes>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

配置文件application.yml如下

spring:
  redis:
    sentinel:
      master: mymaster
      nodes:
        - 192.168.162.10:27001
        - 192.168.162.10:27002
        - 192.168.162.10:27003
logging:
  pattern:
    console: '%date{yyyy-MM-dd HH:mm:ss.SSS} | %highlight(%5level) [%green(%16.16thread)] %clr(%-50.50logger{49}){cyan} %4line -| %highlight(%msg%n)'
  level:
    root: info

创建配置类，配置RedisTemplate

package com.example.config;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

import java.text.SimpleDateFormat;
import java.util.TimeZone;

/**
 * @author ygr
 * @date 2022-02-15 16:30
 */
@Slf4j
@Configuration
public class RedisConfig {

    public ObjectMapper objectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
        objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
        return objectMapper;
    }

    @Bean
    @ConditionalOnMissingBean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        // 创建RedisTemplate<String, Object>对象
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(factory);

        // 定义Jackson2JsonRedisSerializer序列化对象
        Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<>(Object.class);
        jackson2JsonRedisSerializer.setObjectMapper(objectMapper());

        StringRedisSerializer stringSerial = new StringRedisSerializer();
        // redis key 序列化方式使用stringSerial
        template.setKeySerializer(stringSerial);
        // redis value 序列化方式使用jackson
        template.setValueSerializer(jackson2JsonRedisSerializer);
        // redis hash key 序列化方式使用stringSerial
        template.setHashKeySerializer(stringSerial);
        // redis hash value 序列化方式使用jackson
        template.setHashValueSerializer(jackson2JsonRedisSerializer);

        template.afterPropertiesSet();
        return template;
    }
}

新建一个RedisInit类来进行测试，该类实现了ApplicationRunner接口，在应用启动后自动运行

package com.example.init;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;

import java.util.concurrent.TimeUnit;

/**
 * @author ygr
 * @date 2022-02-15 16:32
 */
@Slf4j
@RequiredArgsConstructor
@Component
public class RedisInit implements ApplicationRunner {

    private final RedisTemplate<String, Object> redisTemplate;

    @Override
    public void run(ApplicationArguments args) throws Exception {
        for (int i = 0; i < 300; i++) {
            try {
                redisTemplate.opsForValue().set("k" + i, "v" + i);
                log.info("set value success: {}", i);

                Object val = redisTemplate.opsForValue().get("k" + i);
                log.info("get value success: {}", val);
                TimeUnit.SECONDS.sleep(1);
            } catch (Exception e) {
                log.error("error: {}", e.getMessage());
            }
        }
        log.info("finished...");
    }
}

项目结构特别简单

启动项目，查看日志，可以看到读写一切正常。

途中尝试将主节点干掉，接着看日志，从日志中可以看到，主从切换过来后，一切ok

但从info级别日志中，我们是看不出具体的读写连接信息的。将刚刚干掉的主节点重新启动起来，保持一主二从的模式，并修改一下部分包的日志级别为debug，然后再次启动看日志

logging:
  pattern:
    console: '%date{yyyy-MM-dd HH:mm:ss.SSS} | %highlight(%5level) [%green(%16.16thread)] %clr(%-50.50logger{49}){cyan} %4line -| %highlight(%msg%n)'
  level:
    root: info
    io.lettuce.core: debug
    org.springframework.data.redis: debug

这部分日志有点长，我直接截取了一次读写的日志，如下

2022-02-28 15:43:04.962 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            143 -| Fetching Redis Connection from RedisConnectionFactory
2022-02-28 15:43:04.962 | DEBUG [            main] io.lettuce.core.RedisChannelHandler                 175 -| dispatching command AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.962 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            430 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1] write() writeAndFlush command AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.962 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            207 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1] write() done
2022-02-28 15:43:04.963 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             383 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] write(ctx, AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command], promise)
2022-02-28 15:43:04.963 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandEncoder             101 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001] writing command AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.964 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             577 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] Received: 5 bytes, 1 commands in the stack
2022-02-28 15:43:04.964 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             651 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] Stack contains: 1 commands
2022-02-28 15:43:04.964 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.RedisStateMachine          298 -| Decode done, empty stack: true
2022-02-28 15:43:04.964 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             679 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] Completing command AsyncCommand [type=SET, output=StatusOutput [output=OK, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.964 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            389 -| Closing Redis Connection.
2022-02-28 15:43:04.965 |  INFO [            main] com.example.init.RedisInit                           28 -| set value success: 4
2022-02-28 15:43:04.965 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            143 -| Fetching Redis Connection from RedisConnectionFactory
2022-02-28 15:43:04.965 | DEBUG [            main] io.lettuce.core.RedisChannelHandler                 175 -| dispatching command AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.965 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            430 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1] write() writeAndFlush command AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.965 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            207 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1] write() done
2022-02-28 15:43:04.965 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             383 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] write(ctx, AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command], promise)
2022-02-28 15:43:04.966 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandEncoder             101 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001] writing command AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.966 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             577 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] Received: 10 bytes, 1 commands in the stack
2022-02-28 15:43:04.966 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             651 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] Stack contains: 1 commands
2022-02-28 15:43:04.966 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.RedisStateMachine          298 -| Decode done, empty stack: true
2022-02-28 15:43:04.966 | DEBUG [nioEventLoop-6-2] io.lettuce.core.protocol.CommandHandler             679 -| [channel=0x72e65475, /192.168.162.1:61674 -> /192.168.162.10:7001, epid=0x1, chid=0x2] Completing command AsyncCommand [type=GET, output=ValueOutput [output=[B@393ff2f4, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:43:04.967 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            389 -| Closing Redis Connection.
2022-02-28 15:43:04.967 |  INFO [            main] com.example.init.RedisInit                           31 -| get value success: v4

从日志中可以看到，读与写都是走的主节点（目前7001是主）。

如果想做读写分离，也很简单，修改RedisConfig类，加入如下Bean的配置代码

@Bean
public RedisConnectionFactory lettuceConnectionFactory(RedisProperties redisProperties) {
    RedisSentinelConfiguration redisSentinelConfiguration = new RedisSentinelConfiguration(
        redisProperties.getSentinel().getMaster(), new HashSet<>(redisProperties.getSentinel().getNodes())
    );

    LettucePoolingClientConfiguration lettuceClientConfiguration = LettucePoolingClientConfiguration.builder()
        // 读写分离，若主节点能抗住读写并发，则不需要设置，全都走主节点即可
        .readFrom(ReadFrom.ANY_REPLICA)
        .build();

    return new LettuceConnectionFactory(redisSentinelConfiguration, lettuceClientConfiguration);
}

ReadFrom的取值及读取方式的对应关系如下，其中，REPLICA会一直读取的同一个从节点，ANY_REPLICA则会随机选择

ReadFrom	读取方式
`MASTER` / `UPSTREAM`	仅读取主节点
`MASTER_PREFERRED` / `UPSTREAM_PREFERRED`	优先读取主节点，如果主节点不可用，则读取从节点
`REPLICA`/ `SLAVE`（已废弃）	仅读取从节点
`REPLICA_PREFERRED` / `SLAVE_PREFERRED`（已废弃）	优先读取从节点，如果从节点不可用，则读取主节点
`NEAREST`	从最近节点读取
`ANY`	从任何节点读取
`ANY_REPLICA`	从任意一个从节点读取

再重启查看日志

2022-02-28 15:40:58.971 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            143 -| Fetching Redis Connection from RedisConnectionFactory
2022-02-28 15:40:58.971 | DEBUG [            main] io.lettuce.core.RedisChannelHandler                 175 -| dispatching command AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.971 | DEBUG [            main] i.l.c.m.MasterReplicaConnectionProvider             112 -| getConnectionAsync(WRITE)
2022-02-28 15:40:58.971 | DEBUG [            main] io.lettuce.core.RedisChannelHandler                 175 -| dispatching command AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.971 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            430 -| [channel=0x4c2f55eb, /192.168.162.1:61317 -> /192.168.162.10:7001, epid=0x7] write() writeAndFlush command AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.972 | DEBUG [nioEventLoop-6-7] io.lettuce.core.protocol.CommandHandler             383 -| [channel=0x4c2f55eb, /192.168.162.1:61317 -> /192.168.162.10:7001, epid=0x7, chid=0x7] write(ctx, AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command], promise)
2022-02-28 15:40:58.972 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            207 -| [channel=0x4c2f55eb, /192.168.162.1:61317 -> /192.168.162.10:7001, epid=0x7] write() done
2022-02-28 15:40:58.973 | DEBUG [nioEventLoop-6-7] io.lettuce.core.protocol.CommandEncoder             101 -| [channel=0x4c2f55eb, /192.168.162.1:61317 -> /192.168.162.10:7001] writing command AsyncCommand [type=SET, output=StatusOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.974 | DEBUG [nioEventLoop-6-7] io.lettuce.core.protocol.CommandHandler             577 -| [channel=0x4c2f55eb, /192.168.162.1:61317 -> /192.168.162.10:7001, epid=0x7, chid=0x7] Received: 5 bytes, 1 commands in the stack
2022-02-28 15:40:58.974 | DEBUG [nioEventLoop-6-7] io.lettuce.core.protocol.CommandHandler             651 -| [channel=0x4c2f55eb, /192.168.162.1:61317 -> /192.168.162.10:7001, epid=0x7, chid=0x7] Stack contains: 1 commands
2022-02-28 15:40:58.974 | DEBUG [nioEventLoop-6-7] io.lettuce.core.protocol.RedisStateMachine          298 -| Decode done, empty stack: true
2022-02-28 15:40:58.974 | DEBUG [nioEventLoop-6-7] io.lettuce.core.protocol.CommandHandler             679 -| [channel=0x4c2f55eb, /192.168.162.1:61317 -> /192.168.162.10:7001, epid=0x7, chid=0x7] Completing command AsyncCommand [type=SET, output=StatusOutput [output=OK, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.974 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            389 -| Closing Redis Connection.
2022-02-28 15:40:58.974 |  INFO [            main] com.example.init.RedisInit                           28 -| set value success: 4
2022-02-28 15:40:58.974 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            143 -| Fetching Redis Connection from RedisConnectionFactory
2022-02-28 15:40:58.975 | DEBUG [            main] io.lettuce.core.RedisChannelHandler                 175 -| dispatching command AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.975 | DEBUG [            main] i.l.c.m.MasterReplicaConnectionProvider             112 -| getConnectionAsync(READ)
2022-02-28 15:40:58.975 | DEBUG [            main] io.lettuce.core.RedisChannelHandler                 175 -| dispatching command AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.975 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            430 -| [channel=0x83e97184, /192.168.162.1:61318 -> /192.168.162.10:7002, epid=0x8] write() writeAndFlush command AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.975 | DEBUG [nioEventLoop-6-8] io.lettuce.core.protocol.CommandHandler             383 -| [channel=0x83e97184, /192.168.162.1:61318 -> /192.168.162.10:7002, epid=0x8, chid=0x8] write(ctx, AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command], promise)
2022-02-28 15:40:58.975 | DEBUG [            main] io.lettuce.core.protocol.DefaultEndpoint            207 -| [channel=0x83e97184, /192.168.162.1:61318 -> /192.168.162.10:7002, epid=0x8] write() done
2022-02-28 15:40:58.976 | DEBUG [nioEventLoop-6-8] io.lettuce.core.protocol.CommandEncoder             101 -| [channel=0x83e97184, /192.168.162.1:61318 -> /192.168.162.10:7002] writing command AsyncCommand [type=GET, output=ValueOutput [output=null, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.976 | DEBUG [nioEventLoop-6-8] io.lettuce.core.protocol.CommandHandler             577 -| [channel=0x83e97184, /192.168.162.1:61318 -> /192.168.162.10:7002, epid=0x8, chid=0x8] Received: 10 bytes, 1 commands in the stack
2022-02-28 15:40:58.976 | DEBUG [nioEventLoop-6-8] io.lettuce.core.protocol.CommandHandler             651 -| [channel=0x83e97184, /192.168.162.1:61318 -> /192.168.162.10:7002, epid=0x8, chid=0x8] Stack contains: 1 commands
2022-02-28 15:40:58.977 | DEBUG [nioEventLoop-6-8] io.lettuce.core.protocol.RedisStateMachine          298 -| Decode done, empty stack: true
2022-02-28 15:40:58.977 | DEBUG [nioEventLoop-6-8] io.lettuce.core.protocol.CommandHandler             679 -| [channel=0x83e97184, /192.168.162.1:61318 -> /192.168.162.10:7002, epid=0x8, chid=0x8] Completing command AsyncCommand [type=GET, output=ValueOutput [output=[B@75c09ac4, error='null'], commandType=io.lettuce.core.protocol.Command]
2022-02-28 15:40:58.977 | DEBUG [            main] o.s.data.redis.core.RedisConnectionUtils            389 -| Closing Redis Connection.
2022-02-28 15:40:58.977 |  INFO [            main] com.example.init.RedisInit                           31 -| get value success: v4

从日志中可以看到，写操作走的是主节点（7001），读操作走的是从节点（7002），日志太长，没有粘贴其他的，从完整的日志中可以看到，从节点其实是一直随机选择的。