Cannot acquire lock exception in lettuce - spring

Question

We have recently moved form jedis to using lettuce in our production services. However we have hit a roadblock while creating redis distributed locks
We are using non clustered setup of aws elasticache with one master and 2 read repilcas
Configs :
Spring-boot : 2.2.5
spring-boot-starter-data-redis : 2.2.5
spring-data-redis : 2.2.5
spring-integration-redis : 5.2.4
redis : 5.0.6
#Bean
public LettuceConnectionFactory redisConnectionFactory() {
GenericObjectPoolConfig poolingConfig = new GenericObjectPoolConfig();
poolingConfig.setMaxIdle(Integer.valueOf(maxConnections));
poolingConfig.setMaxTotal(Integer.valueOf(maxIdleConnections));
poolingConfig.setMinIdle(Integer.valueOf(minIdleConnections));
poolingConfig.setMaxWaitMillis(-1);
final SocketOptions socketOptions = SocketOptions.builder().connectTimeout(Duration.ofSeconds(10)).build();
final ClientOptions clientOptions = ClientOptions.builder().socketOptions(socketOptions).build();
LettucePoolingClientConfiguration clientOption = LettucePoolingClientConfiguration.builder()
.poolConfig(poolingConfig).readFrom(ReadFrom.REPLICA_PREFERRED)
.commandTimeout(Duration.ofMillis(Long.valueOf(commandTimeout)))
.clientOptions(clientOptions).useSsl().build();
RedisStaticMasterReplicaConfiguration redisStaticMasterReplicaConfiguration = new RedisStaticMasterReplicaConfiguration(
primaryEndPoint, Integer.valueOf(port));
redisStaticMasterReplicaConfiguration.addNode(readerEndPoint, Integer.valueOf(port));
redisStaticMasterReplicaConfiguration.setPassword(password);
/*
* LettuceClientConfiguration clientConfig = LettuceClientConfiguration
* .builder() .useSsl()
*
* .readFrom(new ReadFrom() {
*
* #Override public List<RedisNodeDescription> select(Nodes nodes) {
* List<RedisNodeDescription> allNodes = nodes.getNodes(); int ind =
* Math.abs(index.incrementAndGet() % allNodes.size()); RedisNodeDescription
* selected = allNodes.get(ind);
* //logger.info("Selected random node {} with uri {}", ind, selected.getUri());
* List<RedisNodeDescription> remaining = IntStream.range(0, allNodes.size())
* .filter(i -> i != ind) .mapToObj(allNodes::get).collect(Collectors.toList());
* return Stream.concat( Stream.of(selected), remaining.stream()
* ).collect(Collectors.toList()); } }) .build();
*/
return new LettuceConnectionFactory(redisStaticMasterReplicaConfiguration, clientOption);
}
#Bean
public StringRedisTemplate stringRedisTemplate() {
return new StringRedisTemplate(redisConnectionFactory());
}
LOCKING SERVICE
#Service
public class RedisLockService {
#Autowired
RedisConnectionFactory redisConnectionFactory;
private static final Logger LOGGER = LoggerFactory.getLogger(RedisLockService.class);
public Lock obtainLock(String registryKey,String redisKey,Long lockExpiry){
try{
RedisLockRegistry registry = new RedisLockRegistry(redisConnectionFactory, registryKey, lockExpiry);
Lock lock = registry.obtain(redisKey);
if(lock.tryLock()==false)
{
LOGGER.info("Lock already made");
return null;
}
else
return lock;
}catch (Exception e) {
LOGGER.warn("Unable to acquire lock: ", e);
return null;
}
}
public void unLock(Lock lock) {
if(lock!=null)
lock.unlock();
}
}
error We are getting while trying to call obtainLock function
.RedisSystemException: Error in execution; nested exception is io.lettuce.core.RedisCommandExecutionException: ERR Error running script (call to f_8426c8df41c64d8177dce3ecbbe9146ef3759cd2): #user_script:6: #user_script: 6: -READONLY You can't write against a read only replica.
at org.springframework.integration.redis.util.RedisLockRegistry$RedisLock.rethrowAsLockException(RedisLockRegistry.java:224)
at org.springframework.integration.redis.util.RedisLockRegistry$RedisLock.tryLock(RedisLockRegistry.java:276)
at org.springframework.integration.redis.util.RedisLockRegistry$RedisLock.tryLock(Re

Answer 1

you need to connect to the master read/write node of Redis