Sentinel mode of Redis and the use of RedisTemplate

Redis sentry mode

The principle of a sentinel mode

illustrate:

1. Sentinel has three roles: monitoring, failover and notification
2. How does Sentinel judge whether Redis is healthy?
   ① Send a ping command every 1 second. If there is no response for a certain period of time, it will be considered as subjective offline.
   ② If more than half of sentinels think that the instance is subjectively offline, it will be judged as customer offline.
3. Failover steps
   ① Select a slave as the new master, execute salve no one
   ② Let all nodes execute salve of the new master node
   ③ Modify the configuration of the failed node to salve

Second sentinel cluster construction

1. Add the following content under the sentinel.conf file:

#端口
port 27001 
sentinel announce-ip 192.168.158.101
# mymaster 主节点名称，主节点ip 2:选举master的quorum值
sentinel monitor mymaster 192.168.158.101 2
sentinel down-after-milliseconds mymaster 5000
sentinel failover-timeout mymaster 60000

Three using RedisTemplate to achieve

1. configuration dependencies

<dependency>
	<groupId>org.springframework.book</groupId>
	<artifactId>spring-boot-starter-data-redis</artifacId>
</dependency>

2. Configure setinel cluster configuration

srping:
	redis:
		setinel:
			master:mymaster
			nodes:
				- 192.168.150.101:27001
				- 192.168.150.101:27002
				- 192.168.150.101:27003

3. Configure read-write separation

@Bean
public LettuceClientConfigurationBuilderCustomizer clientConfigurationBuilderCustomizer(){
    
    
	@Override
	public void customize(LettuceClientConfiguration.LettuceClientConfigurationbuilder clientConfugurationBuilder){
    
    
		clientConfugurationBuilder.readFrom(ReadFrom.REPLICA_PREFERRED);
	}
}