doc-exports/docs/dcs/umn/dcs-ug-211011001.html

Lettuce

Access a Redis Cluster instance through Lettuce on an ECS in the same VPC. For more information on how to use other Redis clients, visit https://redis.io/clients.

If a password was set during DCS Redis instance creation, configure the password for connecting to Redis using Lettuce. Do not hard code the plaintext password.

To connect to a single-node, master/standby, or Proxy Cluster instance, use the RedisClient object of Lettuce. To connect to a Redis Cluster instance, use the RedisClusterClient object.

Prerequisites

• The DCS Redis instance you want to access is in the Running state.
• An ECS has been created. For more information on how to create ECSs, see the Elastic Cloud Server User Guide.
• If the ECS runs the Linux OS, ensure that the Java compilation environment has been installed on the ECS.

Procedure

1. View the IP address/domain name and port number of the DCS Redis instance to be accessed.

   For details, see Viewing Details of a DCS Instance.

2. Log in to the ECS.
3. Use Maven to add the following dependency to the pom.xml file:

   <dependency>
     <groupId>io.lettuce</groupId>
     <artifactId>lettuce-core</artifactId>
     <version>6.1.6.RELEASE</version>
   </dependency>

4. Use Lettuce (a Java client) to connect to the DCS instance.
   • Example of using Lettuce to connect to a single-node, master/standby, or Proxy Cluster DCS Redis instance with a single connection

     // password indicates the connection password. If there is no password, delete "password@". If there is a password and it contains special characters, conversion is required.
     RedisClient redisClient = RedisClient.create("redis://password@host:port");
     StatefulRedisConnection<String, String> connection = redisClient.connect();
     RedisCommands<String, String> syncCommands = connection.sync();
     syncCommands.set("key", "value");
     System.out.println("Connected to Redis:" + syncCommands.get("key"));
     // Close the connection.
     connection.close();
     // Close the client.
     redisClient.shutdown();

   • Example of using Lettuce to connect to a single-node, master/standby, or Proxy Cluster DCS Redis instance with connection pooling

     // password indicates the connection password. If there is no password, delete "password@". If there is a password and it contains special characters, conversion is required.
     RedisClient clusterClient = RedisClient.create("redis://password@host:port");
     GenericObjectPoolConfig<StatefulRedisConnection<String, String>> genericObjectPoolConfig = new GenericObjectPoolConfig();
     // Connection pool parameters
     genericObjectPoolConfig.setMaxIdle(3);
     genericObjectPoolConfig.setMinIdle(2);
     genericObjectPoolConfig.setMaxTotal(3);
     genericObjectPoolConfig.setMaxWaitMillis(-1);
     GenericObjectPool<StatefulRedisConnection<String, String>> pool = ConnectionPoolSupport
             .createGenericObjectPool(() -> clusterClient.connect(), genericObjectPoolConfig);
     // Obtain a connection to perform operations.
     try (StatefulRedisConnection<String, String> con = pool.borrowObject()) {
         RedisCommands<String, String> sync = con.sync();
     	sync.set("key", "value");
         System.out.println("Connected by pool:" + sync.get("key"));
     } catch (Exception e) {
         e.printStackTrace();
     }finally {
         // Close the resources.
         pool.close();
         clusterClient.shutdown();
     }

   • Example of using Lettuce to connect to a Redis Cluster

     // password indicates the connection password. If there is no password, delete "password@". If there is a password and it contains special characters, conversion is required.
     RedisClusterClient redisClient = RedisClusterClient.create("redis://password@host:port");
     StatefulRedisClusterConnection<String, String> connection = redisClient.connect();
     RedisAdvancedClusterCommands<String, String> syncCommands = connection.sync();
     syncCommands.set("key", "value");
     System.out.println("Connected to RedisCluster:"+syncCommands.get("key"));
     // Close the connection.
     connection.close();
     // Close the client.
     redisClient.shutdown();

Parent topic: Java