Redis cache metrics doesn't work in SpringBoot version 2.4.2

Question

We are trying to expose our redis cache metrics to Prometheus. Below are what we've done.

We have a class CachingConfig as below,

@Configuration
@EnableCaching
public class CachingConfig {

  private final Duration cacheEntryTtl;

  public CachingConfig(
      @Value("${spring.cache.redis.entryTtl}")
      final Duration cacheEntryTtl
  ) {
    this.cacheEntryTtl = cacheEntryTtl;
  }

  @Bean
  public CacheManager cacheManager(final RedisConnectionFactory redisConnectionFactory) {
    final Map<String, RedisCacheConfiguration> cacheConfigurations = new HashMap<>();
    cacheConfigurations.put("cacheA",cacheConfiguration(cacheEntryTtl));
    cacheConfigurations.put("cacheB",cacheConfiguration(cacheEntryTtl));

    return RedisCacheManager.builder(redisConnectionFactory)
        .cacheDefaults(cacheConfiguration(cacheEntryTtl))
        .withInitialCacheConfigurations(cacheConfigurations)
        .build();
  }
}

And then we are using the Redis cache in our class like below.

public class BusinessService {
    public static final String CACHE_A_NAME = "cacheA"
    private final BusinessServiceClient businessServiceClient;
    private final CacheManager cacheManager;
    private final CacheMetricsRegistrar cacheMetricsRegistrar;

    @PostConstruct
    public void postConstruct() {
        final Cache cache = cacheManager.getCache(CACHE_A_NAME);
        cacheMetricsRegistrar.bindCacheToRegistry(cache);
    }

    @Cacheable(cacheNames = CACHE_A_NAME)
    public Set<String> getOwnersOfProviderAccount(String para1, String para2) {
        return businessServiceClient.getResonponse(para1, para2);
    }
}

And according to this, I also added following lines in our application.properties file.

spring.cache.type=redis
spring.cache.redis.enable-statistics=true

So in theory, the Redis cache metrics should be able to work, however when I check our cache metrics from following URLs.

GET .../actuator/metrics/cache.gets?tag=name:cacheA

the response is always like below, the COUNT is always ZERO, it seems the statistics not working, our Redis cache works though.

{
   "name":"cache.gets",
   "description":"The number of pending requests",
   "baseUnit":null,
   "measurements":[
      {
         "statistic":"COUNT",
         "value":0.0
      }
   ],
   "availableTags":[
      {
         "tag":"result",
         "values":[
            "hit",
            "pending",
            "miss"
         ]
      },
      {
         "tag":"cache",
         "values":[
            "cacheA"
         ]
      },
      {
         "tag":"application",
         "values":[
            "business-service"
         ]
      },
      {
         "tag":"cacheManager",
         "values":[
            "cacheManager"
         ]
      }
   ]
}

And also if we check the metrics from /management/prometheus, here are what we get, all values are ZERO.

# HELP cache_gets_total the number of times cache lookup methods have returned an uncached (newly loaded) value, or null
# TYPE cache_gets_total counter
cache_gets_total{application="business-service",cache="cacheA",cacheManager="cacheManager",name="cacheA",result="miss",} 0.0
cache_gets_total{application="business-service",cache="cacheA",cacheManager="cacheManager",name="cacheA",result="pending",} 0.0
cache_gets_total{application="business-service",cache="cacheA",cacheManager="cacheManager",name="cacheA",result="hit",} 0.0

Is there anything that I miss when I'm configuring the Redis cache metrics? Thanks, any constructive suggestion is appreciated.

Answer 1

You are creating the RedisCacheManager yourself so the cache manager auto-configuration has backed off. As a result, spring.cache.type=redis is unnecessary and, more importantly, spring.cache.redis.enable-statistics=true will have no effect.

To enable statistics on your RedisCacheManager, call the enableStatistics() method on the builder in your cacheManager @Bean method.