Configuring Sentinel Nodes for Redis instance on CloudFoundry

Question

I am switching from a single node Redis to a sentinel based multi-node Redis instance, and since the new instance’s VCAP structure is different and is not handled by default by Spring, I understand we need to parse the VCAP ourselves and configure the Redis bean.

Following the Spring documentation here, this is how I have adapted my Redis beans:

       public RedisConnectionFactory jedisConnectionFactory(JsonArray sentinelNodes) {
              RedisSentinelConfiguration sentinelConfig = new RedisSentinelConfiguration().master("mymaster");
              String hostname;
              String port;
              for (int i = 0; i < sentinelNodes.size(); i++) {
                     JsonObject sentinelNode = sentinelNodes.getJsonObject(i);
                     hostname = sentinelNode.getString("hostname");
                     port = sentinelNode.getString("port");
                     sentinelConfig.sentinel(hostname, Integer.parseInt(port));
              }
              return new JedisConnectionFactory(sentinelConfig);
       }

       @Bean
       public RedisTemplate<String, String> redisTemplate(RedisConnectionFactory cf) {
              JsonArray sentinelNodes = environmentHandler.getSentinelNodesForRedis();
              if (sentinelNodes != null) {
                     cf = jedisConnectionFactory(sentinelNodes);
              }
              RedisTemplate<String, String> redisTemplate = new RedisTemplate<>();
              redisTemplate.setConnectionFactory(cf);
              redisTemplate.setKeySerializer(new StringRedisSerializer());
              redisTemplate.setValueSerializer(new Jackson2JsonRedisSerializer<>(Object.class));
              return redisTemplate;
       }

       @SuppressWarnings("rawtypes")
       @Bean
       public CacheManager cacheManager(RedisTemplate redisTemplate) {
              return new RedisCacheManager(redisTemplate);
       }

I fetch the information for the sentinel nodes from the VCAP and pass it for creating my JedisConnectionFactory. I was able to configure the beans like this, but received an Exception on runtime, stating ‘org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is java.lang.NullPointerException: while trying to invoke the method redis.clients.jedis.JedisShardInfo.getHost() of a null object loaded from local variable 'shardInfo' | at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:204)…’. In my understanding, I configured the JedisConnectionFactory using RedisSentinelConfiguration and not JedisShardInfo, shardInfo should not have been needed for me.

On checking the newer versions of this library, I noticed that this particular code was modified as this. So I adapted to this newer version, but now the application crashes during startup with the following exception.

java.lang.NoSuchMethodError: org.springframework.util.Assert.isTrue(ZLjava/util/function/Supplier;)V | at org.springframework.data.redis.connection.RedisStandaloneConfiguration.(RedisStandaloneConfiguration.java:61) | at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.(JedisConnectionFactory.java:99) | at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.(JedisConnectionFactory.java:111)…

Following the exception took me here, but I don’t see why this exception would be caused.

Could someone be able to point to where I am going wrong or point me to examples of how these multi-node Redis sentinels can be configured through Spring Boot beans?

There is an open issue to add Redis Sentinel support to Spring Cloud Connectors to handle such a case: github.com/spring-cloud/spring-cloud-connectors/issues/185. Would it be possible for you to add an example of the VCAP_SERVICES for your Redis service instance to this issue? That would help us ensure that the solution covers as many types of Redis services as possible. — Scott Frederick
Thanks, @Scott. I have posted my VCAP structure to the issue. Is there an ETA for the enhancement? Also, since I have already done the parsing of this VCAP and configuration of sentinel nodes, any idea why I face the exception stated above in the RedisStandaloneConfiguration class of spring-data-redis? — Nisheeth Agarwal

Nisheeth Agarwal Nisheeth Agarwal · Accepted Answer · 2017-11-03T11:17:01

Calling the afterPropertiesSet() method before returning the RedisConnectionFactory seems to have done the trick for now.

(Also, have set the password for the Factory.)

Configuring Sentinel Nodes for Redis instance on CloudFoundry

1 Answers