How can one set up Redis Sentinel in Micronaut?

edit

To set up Redis Sentinel in Micronaut, follow these steps:

1. Add the lettuce-core and lettuce-sentinel dependencies to your project:

implementation("io.lettuce:lettuce-core:5.3.5.RELEASE")
implementation("io.lettuce:lettuce-sentinel:5.3.5.RELEASE")

1. Create a RedisSentinelClient bean in your Micronaut application:

@Singleton
public class RedisSentinelClient {

    private final RedisURI redisUri;
    private final RedisClient redisClient;
    private final StatefulRedisSentinelConnection<String, String> connection;

    public RedisSentinelClient(
        @Value("${redis.sentinel.master-name}") String masterName,
        @Value("${redis.sentinel.nodes}") String nodes
    ) {
        redisUri = RedisURI.Builder.sentinel(nodes, masterName).build();
        redisClient = RedisClient.create(redisUri);
        connection = redisClient.connectSentinel();
    }

    public StatefulRedisConnection<String, String> getConnection() {
        return connection.master();
    }

    @PreDestroy
    public void close() {
        redisClient.shutdown();
    }
}

This bean initializes a RedisSentinelClient with the masterName and nodes properties, which should be set in your application configuration. The getConnection() method returns a StatefulRedisConnection to the master Redis instance.

1. Use the RedisSentinelClient in your Micronaut application. For example, you can inject it into a controller:

@Controller("/example")
public class ExampleController {

    private final RedisSentinelClient redisSentinelClient;

    public ExampleController(RedisSentinelClient redisSentinelClient) {
        this.redisSentinelClient = redisSentinelClient;
    }

    @Get("/{id}")
    public String getById(@PathVariable("id") Long id) {
        StatefulRedisConnection<String, String> connection = redisSentinelClient.getConnection();
        RedisCommands<String, String> commands = connection.sync();
        String value = commands.get(id.toString());
        connection.close();
        return value;
    }
}

This controller injects the RedisSentinelClient and uses it to get a StatefulRedisConnection to the master Redis instance. It then uses the RedisCommands API to get a value from Redis and closes the connection.

That's it! You now have a Micronaut application set up with Redis Sentinel.