Clear Redis Cache on Spring Boot Application Startup

Question

On application (spring boot service) startup, need to clear the Redis cache.

Redis is running in a different docker container with own volume mapping. Since it retains the old cache, the application picks the data from Redis cache instead of Database even after the application restarts

• Tried @EventListener for ContextRefreshedEvent and it is never getting called.
• Tried with @PostConstruct in ApplicationMain class, but it doesn't clear the cache.

• Tried using @CacheEvict(allEntries = true), but still no luck

  @Component public class ApplicationStartUp {

  @Autowired
  private CacheManager cacheManager;
  
  @EventListener()
  public void onApplicationEvent(ContextStartedEvent event) {
      cacheManager.getCacheNames()
                  .parallelStream()
                  .forEach(n -> cacheManager.getCache(n).clear());
  }
  

  }

Answer 1

I was successfully able to clear the cache with ApplicationReadyEvent. As the CacheManager bean is available by the time, the cache is getting cleared properly on startup

@Autowired
private CacheManager cacheManager;

@EventListener
public void onApplicationEvent(ApplicationReadyEvent event) {
    cacheManager.getCacheNames()
                .parallelStream()
                .forEach(n -> cacheManager.getCache(n).clear());
}

Answer 2

A simple practice to clear Redis DB at earlier life cycle stage. To config CacheManager @bean with argument RedisConnectionFactory passed in, calling flushDb() to delete all keys of the currently selected database before build up.

 @Bean
    public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
        redisConnectionFactory.getConnection().flushDb(); //Delete all keys of the currently selected database
        return RedisCacheManager.builder(RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory)).cacheDefaults(RedisCacheConfiguration.defaultCacheConfig()).build();
    }