Don't Let Your Spring Boot App Bleed Redis Memory

You're probably using Redis for caching in your Spring Boot app, right? Great choice. But I've seen apps absolutely tank because of memory bloat in Redis. Often, it's simple cache expiration issues. You set a TTL (Time To Live) but maybe the underlying data is changing too frequently or your eviction policy isn't aggressive enough.

Here's a quick check. In your application.properties or application.yml, make sure your spring.redis.client-type is set to lettuce (it's the default and generally good) and then focus on your eviction policy. If you're using RedisTemplate, ensure your cache configurations are sound. Something like this, for instance, isn't enough on its own if your data churns:

// Example: Without proper eviction policy, this might still cause bloat
@Bean
public RedisCacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
    RedisCacheConfiguration cacheConfig = RedisCacheConfiguration.defaultCacheConfig()
            .entryTtl(Duration.ofMinutes(5)); // This is just expiration
    return RedisCacheManager.builder(redisConnectionFactory)
            .cacheWriter(RedisCacheWriter.lockingRedisCacheWriter(redisConnectionFactory))
            .withCacheConfiguration("myCache", cacheConfig)
            .build();
}

Instead, consider setting an eviction policy like ALLKEYS_LRU or VOLATILE_LRU directly in your redis.conf or via Redis commands. It means Redis will actively kick out less recently used items when it needs space, saving you from those surprise memory bills.