[automatic failover] Automatic failover client improvements (part 4) (#4317)

* [automatic failover] Replace EchoStrategy with PingStrategy (#4313)

* - replace EchoStrategy with PingStrategy

* - fix doc

* [automatic failover] Remove UnifiedJedis experimental constructor accepting MultiDbConnectionProvider (#4316)

* Remove UnifiedJedis(MultiDbConnectionProvider) experimental constructor

The recommended way to create MultiDbClient is using MultiDbClient.builder().
Update all tests to use the builder pattern.

Fixes #4307

* revert unintentional change in MultiDbClientBuilder

* Squashed commit of the following:

commit 297279e
Author: Igor Malinovskiy <u.glide@gmail.com>
Date:   Thu Oct 9 13:06:10 2025 +0200

    Add v6 and v7 migration guides (#4315)

    * Add migration guide for v7

    * Move all migration guides to subfolder

    * Update readme:

    - Bump client version
    - Update list of supported Redis versions
    - Remove references to JedisPool
    - Remove reference to Google Group

    * Remove duplicated content in the migration guide

    * Update README.md

    Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

    * Add missing v5 to v6 migration guide

    * Fix broken link

    * Update outdated modules section in README

    ---------

    Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

commit 3645601
Author: Ivo Gaydazhiev <ivo.gaydazhiev@redis.com>
Date:   Thu Oct 9 13:53:02 2025 +0300

    Dedicated profile for running Scenario tests (#4312)

    * Dedicated profile for running Scenario tests

      to run only scenario tests
      mvn -Pscenario-tests clean verify

    * format

    * remove import after rebase conflict

    * fix RedisRestAPIIT scenario test

     - increase expected bdb's count to account for additional db added to test env
     - fix incorrect bdbid used for lag-aware availablity checks
        now using bdb of'"re-active-active"

    * fix LagAwareStrategySslIT scenario test

     - Now exception is propagated in case of ssl connection errors instead of returning UNHEALTHY
     - updated the test to current expectations
     - Enhanced test to ensure untrusted default certificate

    * java 8 compatibility

    * remove @tag("integration") from IntegrationTest* to avoid multiple runs of same test

    ---------

    Co-authored-by: Igor Malinovskiy <u.glide@gmail.com>

commit 07bf3b0
Author: Igor Malinovskiy <u.glide@gmail.com>
Date:   Thu Oct 9 12:00:36 2025 +0200

    [automatic failover] Update failover docs (#4314)

    Update failover docs

    - Add migration guide from 6.x to 7.0
    - Add instructions on optional deps
    - Clean up wording to refer to multiDbClient instead of connection provider

commit 158e726
Author: Igor Malinovskiy <u.glide@gmail.com>
Date:   Thu Oct 9 11:14:28 2025 +0200

    Remove deprecated constructors, classes and JedisSharding (#4311)

    * Remove JedisSharding

    * Remove deprecated constructors in UnifiedJedis

    * Clean up UnifiedJedisConstructorReflectionTest

    * Remove remaining ShardedCommandArguments

    * Remove deprecated PipelineBase

    * Remove deprecated TransactionBase

    * Remove unused attr in MultiDbTransaction

commit 5db1a39
Author: Igor Malinovskiy <u.glide@gmail.com>
Date:   Thu Oct 9 10:04:06 2025 +0200

    Remove spellcheck (#4309)

    Nowadays, AI reviewing tools like CoPilot catch spellcheck issues better than pyspelling without a burden of maintaining wordlist.txt

---------

Co-authored-by: Ivo Gaydazhiev <ivo.gaydazhiev@redis.com>

Author: atakavci

docs/failover.md

@@ -209,18 +209,18 @@ The health check system operates independently of your application traffic, runn
 
 #### Available Health Check Types
 
-##### 1. EchoStrategy (Default)
+##### 1. PingStrategy (Default)
 
-The `EchoStrategy` is the default health check implementation that uses Redis's `ECHO` command to verify both connectivity and write capability.
+The `PingStrategy` is the default health check implementation that uses Redis's `PING` command to verify both connectivity and write capability.
 
 **Use Cases:**
 - General-purpose health checking for most Redis deployments
 - Verifying both read and write operations
 - Simple connectivity validation
 
 **How it works:**
-- Sends `ECHO "HealthCheck"` command to the Redis server
-- Expects exact response `"HealthCheck"` to consider the server healthy
+- Sends `PING` command to the Redis server
+- Expects exact response `"PONG"` to consider the server healthy
 - Any exception or unexpected response marks the server as unhealthy
 
 ##### 2. LagAwareStrategy [PREVIEW] (Redis Enterprise)

src/main/java/redis/clients/jedis/MultiDbConfig.java

@@ -11,7 +11,7 @@
 import redis.clients.jedis.exceptions.JedisConnectionException;
 import redis.clients.jedis.exceptions.JedisValidationException;
 import redis.clients.jedis.mcf.ConnectionFailoverException;
-import redis.clients.jedis.mcf.EchoStrategy;
+import redis.clients.jedis.mcf.PingStrategy;
 import redis.clients.jedis.mcf.HealthCheckStrategy;
 
 /**
@@ -71,7 +71,7 @@
  * </p>
  * @see redis.clients.jedis.mcf.MultiDbConnectionProvider
  * @see redis.clients.jedis.mcf.HealthCheckStrategy
- * @see redis.clients.jedis.mcf.EchoStrategy
+ * @see redis.clients.jedis.mcf.PingStrategy
  * @see redis.clients.jedis.mcf.LagAwareStrategy
  * @since 7.0
  */
@@ -90,13 +90,13 @@ public final class MultiDbConfig {
    * <strong>Common Implementations:</strong>
    * </p>
    * <ul>
-   * <li>{@link redis.clients.jedis.mcf.EchoStrategy#DEFAULT} - Uses Redis ECHO command for health
+   * <li>{@link redis.clients.jedis.mcf.PingStrategy#DEFAULT} - Uses Redis PING command for health
    * checks</li>
    * <li>Custom implementations for specific monitoring requirements</li>
    * <li>Redis Enterprise implementations using REST API monitoring</li>
    * </ul>
    * @see redis.clients.jedis.mcf.HealthCheckStrategy
-   * @see redis.clients.jedis.mcf.EchoStrategy
+   * @see redis.clients.jedis.mcf.PingStrategy
    * @see redis.clients.jedis.mcf.LagAwareStrategy
    */
   public static interface StrategySupplier {
@@ -839,15 +839,15 @@ public static class DatabaseConfig {
 
     /**
      * Strategy supplier for creating health check instances for this database. Default is
-     * EchoStrategy.DEFAULT.
+     * PingStrategy.DEFAULT.
      */
     private StrategySupplier healthCheckStrategySupplier;
 
     /**
      * Constructs a DatabaseConfig with basic endpoint and client configuration.
      * <p>
      * This constructor creates a database configuration with default settings: weight of 1.0f and
-     * EchoStrategy for health checks. Use the {@link Builder} for more advanced configuration
+     * PingStrategy for health checks. Use the {@link Builder} for more advanced configuration
      * options.
      * </p>
      * @param endpoint the Redis endpoint (host and port)
@@ -863,7 +863,7 @@ public DatabaseConfig(Endpoint endpoint, JedisClientConfig clientConfig) {
      * Constructs a DatabaseConfig with endpoint, client, and connection pool configuration.
      * <p>
      * This constructor allows specification of connection pool settings in addition to basic
-     * endpoint configuration. Default weight of 1.0f and EchoStrategy for health checks are used.
+     * endpoint configuration. Default weight of 1.0f and PingStrategy for health checks are used.
      * </p>
      * @param endpoint the Redis endpoint (host and port)
      * @param clientConfig the Jedis client configuration
@@ -963,7 +963,7 @@ public StrategySupplier getHealthCheckStrategySupplier() {
      * </p>
      * <ul>
      * <li><strong>Weight:</strong> 1.0f (standard priority)</li>
-     * <li><strong>Health Check:</strong> {@link redis.clients.jedis.mcf.EchoStrategy#DEFAULT}</li>
+     * <li><strong>Health Check:</strong> {@link redis.clients.jedis.mcf.PingStrategy#DEFAULT}</li>
      * <li><strong>Connection Pool:</strong> null (uses default pooling)</li>
      * </ul>
      */
@@ -980,8 +980,8 @@ public static class Builder {
       /** Weight for database selection priority. Default: 1.0f */
       private float weight = 1.0f;
 
-      /** Health check strategy supplier. Default: EchoStrategy.DEFAULT */
-      private StrategySupplier healthCheckStrategySupplier = EchoStrategy.DEFAULT;
+      /** Health check strategy supplier. Default: PingStrategy.DEFAULT */
+      private StrategySupplier healthCheckStrategySupplier = PingStrategy.DEFAULT;
 
       /**
        * Constructs a new Builder with required endpoint and client configuration.
@@ -1089,7 +1089,7 @@ public Builder healthCheckStrategy(HealthCheckStrategy healthCheckStrategy) {
        * </ul>
        * <p>
        * When health checks are enabled (true) and no strategy supplier was previously set, the
-       * default {@link redis.clients.jedis.mcf.EchoStrategy#DEFAULT} will be used.
+       * default {@link redis.clients.jedis.mcf.PingStrategy#DEFAULT} will be used.
        * </p>
        * @param healthCheckEnabled true to enable health checks, false to disable
        * @return this builder instance for method chaining
@@ -1098,7 +1098,7 @@ public Builder healthCheckEnabled(boolean healthCheckEnabled) {
         if (!healthCheckEnabled) {
           this.healthCheckStrategySupplier = null;
         } else if (healthCheckStrategySupplier == null) {
-          this.healthCheckStrategySupplier = EchoStrategy.DEFAULT;
+          this.healthCheckStrategySupplier = PingStrategy.DEFAULT;
         }
         return this;
       }

src/main/java/redis/clients/jedis/UnifiedJedis.java

@@ -194,18 +194,6 @@ public UnifiedJedis(ConnectionProvider provider, int maxAttempts, Duration maxTo
     this(new RetryableCommandExecutor(provider, maxAttempts, maxTotalRetriesDuration), provider);
   }
 
-  /**
-   * Constructor which supports multiple cluster/database endpoints each with their own isolated connection pool.
-   * <p>
-   * With this Constructor users can seamlessly failover to Disaster Recovery (DR), Backup, and Active-Active cluster(s)
-   * by using simple configuration which is passed through from Resilience4j - https://resilience4j.readme.io/docs
-   * <p>
-   */
-  @Experimental
-  public UnifiedJedis(MultiDbConnectionProvider provider) {
-    this(new MultiDbCommandExecutor(provider), provider);
-  }
-
   /**
    * The constructor to use a custom {@link CommandExecutor}.
    * <p>

src/main/java/redis/clients/jedis/mcf/EchoStrategy.java renamed to src/main/java/redis/clients/jedis/mcf/PingStrategy.java

@@ -10,17 +10,17 @@
 import redis.clients.jedis.UnifiedJedis;
 import redis.clients.jedis.MultiDbConfig.StrategySupplier;
 
-public class EchoStrategy implements HealthCheckStrategy {
+public class PingStrategy implements HealthCheckStrategy {
   private static final int MAX_HEALTH_CHECK_POOL_SIZE = 2;
 
   private final UnifiedJedis jedis;
   private final HealthCheckStrategy.Config config;
 
-  public EchoStrategy(HostAndPort hostAndPort, JedisClientConfig jedisClientConfig) {
+  public PingStrategy(HostAndPort hostAndPort, JedisClientConfig jedisClientConfig) {
     this(hostAndPort, jedisClientConfig, HealthCheckStrategy.Config.create());
   }
 
-  public EchoStrategy(HostAndPort hostAndPort, JedisClientConfig jedisClientConfig,
+  public PingStrategy(HostAndPort hostAndPort, JedisClientConfig jedisClientConfig,
       HealthCheckStrategy.Config config) {
     GenericObjectPoolConfig<Connection> poolConfig = new GenericObjectPoolConfig<>();
     poolConfig.setMaxTotal(MAX_HEALTH_CHECK_POOL_SIZE);
@@ -55,15 +55,14 @@ public int getDelayInBetweenProbes() {
 
   @Override
   public HealthStatus doHealthCheck(Endpoint endpoint) {
-    return "HealthCheck".equals(jedis.echo("HealthCheck")) ? HealthStatus.HEALTHY
-        : HealthStatus.UNHEALTHY;
+    return "PONG".equals(jedis.ping()) ? HealthStatus.HEALTHY : HealthStatus.UNHEALTHY;
   }
 
   @Override
   public void close() {
     jedis.close();
   }
 
-  public static final StrategySupplier DEFAULT = EchoStrategy::new;
+  public static final StrategySupplier DEFAULT = PingStrategy::new;
 
 }

src/test/java/redis/clients/jedis/failover/FailoverIntegrationTest.java

@@ -16,6 +16,7 @@
 import redis.clients.jedis.EndpointConfig;
 import redis.clients.jedis.HostAndPorts;
 import redis.clients.jedis.JedisClientConfig;
+import redis.clients.jedis.MultiDbClient;
 import redis.clients.jedis.MultiDbConfig;
 import redis.clients.jedis.UnifiedJedis;
 import redis.clients.jedis.exceptions.JedisConnectionException;
@@ -58,7 +59,7 @@ public class FailoverIntegrationTest {
   private static String JEDIS1_ID = "";
   private static String JEDIS2_ID = "";
   private MultiDbConnectionProvider provider;
-  private UnifiedJedis failoverClient;
+  private MultiDbClient failoverClient;
 
   @BeforeAll
   public static void setupAdminClients() throws IOException {
@@ -110,7 +111,7 @@ public void setup() throws IOException {
 
     // Create default provider and client for most tests
     provider = createProvider();
-    failoverClient = new UnifiedJedis(provider);
+    failoverClient = MultiDbClient.builder().connectionProvider(provider).build();
   }
 
   @AfterEach
@@ -272,7 +273,7 @@ public void testCircuitBreakerCountsEachConnectionErrorSeparately() throws IOExc
           .build();
 
     MultiDbConnectionProvider provider = new MultiDbConnectionProvider(failoverConfig);
-    try (UnifiedJedis client = new UnifiedJedis(provider)) {
+    try (MultiDbClient client = MultiDbClient.builder().connectionProvider(provider).build()) {
       // Verify initial connection to first endpoint
       assertThat(getNodeId(client.info("server")), equalTo(JEDIS1_ID));
 
@@ -321,7 +322,8 @@ public void testInflightCommandsAreRetriedAfterFailover() throws Exception {
       builder -> builder.retryOnFailover(true));
 
     // Create a custom client with retryOnFailover enabled for this specific test
-    try (UnifiedJedis customClient = new UnifiedJedis(customProvider)) {
+    try (MultiDbClient customClient = MultiDbClient.builder().connectionProvider(customProvider)
+        .build()) {
 
       assertThat(getNodeId(customClient.info("server")), equalTo(JEDIS1_ID));
       Thread.sleep(1000);
@@ -362,7 +364,8 @@ public void testInflightCommandsAreNotRetriedAfterFailover() throws Exception {
     MultiDbConnectionProvider customProvider = createProvider(
       builder -> builder.retryOnFailover(false));
 
-    try (UnifiedJedis customClient = new UnifiedJedis(customProvider)) {
+    try (MultiDbClient customClient = MultiDbClient.builder().connectionProvider(customProvider)
+        .build()) {
 
       assertThat(getNodeId(customClient.info("server")), equalTo(JEDIS1_ID));
       Future<List<String>> blpop = executor.submit(() -> customClient.blpop(500, "test-list-2"));

src/test/java/redis/clients/jedis/mcf/ActiveActiveLocalFailoverTest.java

@@ -23,6 +23,7 @@
 import redis.clients.jedis.scenario.RecommendedSettings;
 import redis.clients.jedis.scenario.FaultInjectionClient.TriggerActionResponse;
 import redis.clients.jedis.exceptions.JedisConnectionException;
+import redis.clients.jedis.util.ClientTestUtil;
 
 import java.io.IOException;
 import java.time.Duration;
@@ -152,13 +153,12 @@ public void accept(DatabaseSwitchEvent e) {
     ensureEndpointAvailability(endpoint1.getHostAndPort(), config);
     ensureEndpointAvailability(endpoint2.getHostAndPort(), config);
 
-    // Create the connection provider
-    MultiDbConnectionProvider provider = new MultiDbConnectionProvider(builder.build());
     FailoverReporter reporter = new FailoverReporter();
-    provider.setDatabaseSwitchListener(reporter);
-    provider.setActiveDatabase(endpoint1.getHostAndPort());
 
-    UnifiedJedis client = new UnifiedJedis(provider);
+    MultiDbClient multiDbClient = MultiDbClient.builder().multiDbConfig(builder.build())
+        .databaseSwitchListener(reporter).build();
+
+    multiDbClient.setActiveDatabase(endpoint1.getHostAndPort());
 
     AtomicLong retryingThreadsCounter = new AtomicLong(0);
     AtomicLong failedCommandsAfterFailover = new AtomicLong(0);
@@ -168,33 +168,32 @@ public void accept(DatabaseSwitchEvent e) {
     AtomicBoolean unexpectedErrors = new AtomicBoolean(false);
     AtomicReference<Exception> lastException = new AtomicReference<Exception>();
     AtomicLong stopRunningAt = new AtomicLong();
-    String database2Id = provider.getDatabase(endpoint2.getHostAndPort()).getCircuitBreaker()
-        .getName();
+    Endpoint db2Endpoint = endpoint2.getHostAndPort();
 
-    // Start thread that imitates an application that uses the client
+    // Start thread that imitates an application that uses the multiDbClient
     RateLimiterConfig rateLimiterConfig = RateLimiterConfig.custom().limitForPeriod(100)
         .limitRefreshPeriod(Duration.ofSeconds(1)).timeoutDuration(Duration.ofSeconds(1)).build();
 
-    MultiThreadedFakeApp fakeApp = new MultiThreadedFakeApp(client, (UnifiedJedis c) -> {
+    MultiThreadedFakeApp fakeApp = new MultiThreadedFakeApp(multiDbClient, (UnifiedJedis c) -> {
 
       long threadId = Thread.currentThread().getId();
 
       int attempt = 0;
       int maxTries = 500;
       int retryingDelay = 5;
-      String currentDatabaseId = null;
+      String currentDbKey = null;
       while (true) {
         try {
           if (System.currentTimeMillis() > stopRunningAt.get()) break;
-          currentDatabaseId = provider.getDatabase().getCircuitBreaker().getName();
+          currentDbKey = dbKey(multiDbClient.getActiveDatabaseEndpoint());
           Map<String, String> executionInfo = new HashMap<String, String>() {
             {
               put("threadId", String.valueOf(threadId));
               put("database", reporter.getCurrentDatabaseName());
             }
           };
 
-          client.xadd("execution_log", StreamEntryID.NEW_ENTRY, executionInfo);
+          multiDbClient.xadd("execution_log", StreamEntryID.NEW_ENTRY, executionInfo);
 
           if (attempt > 0) {
             log.info("Thread {} recovered after {} ms. Threads still not recovered: {}", threadId,
@@ -203,7 +202,7 @@ public void accept(DatabaseSwitchEvent e) {
 
           break;
         } catch (JedisConnectionException e) {
-          if (database2Id.equals(currentDatabaseId)) {
+          if (dbKey(db2Endpoint).equals(currentDbKey)) {
             break;
           }
           lastException.set(e);
@@ -231,7 +230,7 @@ public void accept(DatabaseSwitchEvent e) {
           }
           if (++attempt == maxTries) throw e;
         } catch (Exception e) {
-          if (database2Id.equals(currentDatabaseId)) {
+          if (dbKey(db2Endpoint).equals(currentDbKey)) {
             break;
           }
           lastException.set(e);
@@ -275,6 +274,7 @@ public boolean isCompleted(Duration checkInterval, Duration delayAfter, Duration
     }
     log.info("Fake app completed");
 
+    MultiDbConnectionProvider provider = ClientTestUtil.getConnectionProvider(multiDbClient);
     ConnectionPool pool = provider.getDatabase(endpoint1.getHostAndPort()).getConnectionPool();
 
     log.info("First connection pool state: active: {}, idle: {}", pool.getNumActive(),
@@ -305,7 +305,11 @@ public boolean isCompleted(Duration checkInterval, Duration delayAfter, Duration
     }
     assertFalse(unexpectedErrors.get());
 
-    client.close();
+    multiDbClient.close();
+  }
+
+  private String dbKey(Endpoint endpoint) {
+    return endpoint.getHost() + ":" + endpoint.getPort();
   }
 
   private static void ensureEndpointAvailability(HostAndPort endpoint, JedisClientConfig config) {

src/test/java/redis/clients/jedis/mcf/DefaultValuesTest.java

@@ -33,8 +33,8 @@ void testDefaultValuesInConfig() {
     // check healthchecks enabled
     assertNotNull(databaseConfig.getHealthCheckStrategySupplier());
 
-    // check default healthcheck strategy is echo
-    assertEquals(EchoStrategy.DEFAULT, databaseConfig.getHealthCheckStrategySupplier());
+    // check default healthcheck strategy is PingStrategy
+    assertEquals(PingStrategy.DEFAULT, databaseConfig.getHealthCheckStrategySupplier());
 
     // check number of probes
     assertEquals(3,