I solved this problem as follows: in short, I added the “ping” method, which tries to set and get the value from Redis; if it's possible, then application is ready.
Implementation:
First, you need to update app.yaml add following:
readiness_check:
path: "/readiness_check"
check_interval_sec: 5
timeout_sec: 4
failure_threshold: 2
success_threshold: 2
app_start_timeout_sec: 300
Second, in your rest controller:
@GetMapping("/readiness_check")
public ResponseEntity<?> readiness_check() {
if (!cacheConfig.ping()) {
return ResponseEntity.notFound().build();
}
return ResponseEntity.ok().build();
}
Third, class CacheConfig:
public boolean ping() {
long prefix = System.currentTimeMillis();
try {
redisTemplate.opsForValue().set("readiness_check_" + prefix, Boolean.TRUE, 100, TimeUnit.SECONDS);
Boolean val = (Boolean) redisTemplate.opsForValue().get("readiness_check_" + prefix);
return Boolean.TRUE.equals(val);
} catch (Exception e) {
LOGGER.info("ping failed for " + System.currentTimeMillis());
return false;
}
}
P.S.
Also if somebody needs the full implementation of CacheConfig:
@Configuration
public class CacheConfig {
private static final Logger LOGGER = Logger.getLogger(CacheConfig.class.getName());
@Value("${spring.redis.host}")
private String redisHost;
private final RedisTemplate<String, Object> redisTemplate;
@Autowired
public CacheConfig(@Lazy RedisTemplate<String, Object> redisTemplate) {
this.redisTemplate = redisTemplate;
}
@Bean
JedisConnectionFactory jedisConnectionFactory(
@Autowired JedisPoolConfig poolConfig
) {
// https://cloud.google.com/memorystore/docs/redis/quotas
RedisStandaloneConfiguration config = new RedisStandaloneConfiguration(redisHost, 6379);
JedisClientConfiguration clientConfig = JedisClientConfiguration
.builder()
.usePooling()
.poolConfig(poolConfig)
.build();
return new JedisConnectionFactory(config, clientConfig);
}
@Bean
public RedisTemplate<String, Object> redisTemplate(
@Autowired JedisConnectionFactory jedisConnectionFactory
) {
RedisTemplate<String, Object> template = new RedisTemplate<>();
template.setConnectionFactory(jedisConnectionFactory);
template.setKeySerializer(new StringRedisSerializer());
template.setValueSerializer(new GenericJackson2JsonRedisSerializer(newObjectMapper()));
return template;
}
/**
* Example: https://github.com/PengliuIBM/pws_demo/blob/1becdca1bc19320c2742504baa1cada3260f8d93/redisData/src/main/java/com/pivotal/wangyu/study/springdataredis/config/RedisConfig.java
*/
@Bean
redis.clients.jedis.JedisPoolConfig jedisPoolConfig() {
final redis.clients.jedis.JedisPoolConfig poolConfig = new redis.clients.jedis.JedisPoolConfig();
// Maximum active connections to Redis instance
poolConfig.setMaxTotal(16);
// Number of connections to Redis that just sit there and do nothing
poolConfig.setMaxIdle(16);
// Minimum number of idle connections to Redis - these can be seen as always open and ready to serve
poolConfig.setMinIdle(8);
// Tests whether connection is dead when returning a connection to the pool
poolConfig.setTestOnBorrow(true);
// Tests whether connection is dead when connection retrieval method is called
poolConfig.setTestOnReturn(true);
// Tests whether connections are dead during idle periods
poolConfig.setTestWhileIdle(true);
return poolConfig;
}
public boolean ping() {
long prefix = System.currentTimeMillis();
try {
redisTemplate.opsForValue().set("readiness_check_" + prefix, Boolean.TRUE, 100, TimeUnit.SECONDS);
Boolean val = (Boolean) redisTemplate.opsForValue().get("readiness_check_" + prefix);
return Boolean.TRUE.equals(val);
} catch (Exception e) {
LOGGER.info("ping failed for " + System.currentTimeMillis());
return false;
}
}
}
