Consider replacing Jedis with Lettuce in `spring-boot-starter-data-redis`

[vpavic]

Currently spring-boot-starter-data-redis pulls in Jedis while newly introduced spring-boot-starter-data-redis-reactive pulls in Lettuce as Redis driver.

Since Lettuce is preferred choice for many and now has first-class support in Boot, perhaps the driver choice in spring-boot-starter-data-redis could be reconsidered for Boot 2.0.

[mp911de]

Lettuce has been the default client for quite a while until in 2014 Lettuce was no longer maintained. Jedis became the defacto standard client for Java applications see (#745).

Adoption of the new Lettuce fork was introduced in Spring Data Redis about two years ago and in Spring Boot only recently (with 2.0 M1). Changing the default client library impacts quite a few things so a change can cause issues for existing users. Jedis is supported for over three years, so all former sharp corners are quite polished by now.

As far as I understood the Boot team, it's not entirely opposed to the change. They want to collect some feedback from using Lettuce with the reactive starter for a later decision. Also, Spring Data needs to polish up pooling support for Lettuce.

Right now, Spring Boot defaults to Lettuce, if you have both drivers on the classpath.

[snicoll]

Thanks @mp911de - I agree with that analysis. We can reconsider this later.

[ahmetgeymen]

@mp911de

Right now, Spring Boot defaults to Lettuce, if you have both drivers on the classpath.

Hello, how can we see this preference, can you share any code link on GitHub for this distinction.

[wilkinsona]

@ahmetgeymen It's determined by the import ordering in RedisAutoConfiguration:

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/RedisAutoConfiguration.java

Line 50 in a03426a

@Import({ LettuceConnectionConfiguration.class, JedisConnectionConfiguration.class })

[ahmetgeymen]

@wilkinsona
Thanks for the answer, I've seen this line but when it imports both configuration class I couldn't understand where the exact decision made. During migration from Spring Boot from 1.5 to 2.0 it is stated that Lettuce is the default driver.

https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.0-Migration-Guide#redis

I'm a bit obsessed with finding the exact line or the explanation how it choose Lettuce instead Jedis.

Thanks again.

[wilkinsona]

LettuceConnectionConfiguration will define a RedisConnectionFactory bean:

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/LettuceConnectionConfiguration.java

Lines 69 to 77 in 23c5549

	@Bean
	@ConditionalOnMissingBean(RedisConnectionFactory.class)
	LettuceConnectionFactory redisConnectionFactory(
	ObjectProvider<LettuceClientConfigurationBuilderCustomizer> builderCustomizers,
	ClientResources clientResources) throws UnknownHostException {
	LettuceClientConfiguration clientConfig = getLettuceClientConfiguration(builderCustomizers, clientResources,
	getProperties().getLettuce().getPool());
	return createLettuceConnectionFactory(clientConfig);
	}

This bean's definition that causes JedisConnectionConfiguration to back off as it's definition of a RedisConnectionFactory bean is conditional on such a bean being missing:

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/JedisConnectionConfiguration.java

Lines 56 to 61 in 23c5549

	@Bean
	@ConditionalOnMissingBean(RedisConnectionFactory.class)
	JedisConnectionFactory redisConnectionFactory(
	ObjectProvider<JedisClientConfigurationBuilderCustomizer> builderCustomizers) throws UnknownHostException {
	return createJedisConnectionFactory(builderCustomizers);
	}

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