Merge pull request #42588 from nosan

* pr/42588:
  Polish "Add spring.data.redis.lettuce.read-from property"
  Add spring.data.redis.lettuce.read-from property

Closes gh-42588

Author: snicoll

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/LettuceConnectionConfiguration.java

@@ -19,6 +19,7 @@
 import java.time.Duration;
 
 import io.lettuce.core.ClientOptions;
+import io.lettuce.core.ReadFrom;
 import io.lettuce.core.RedisClient;
 import io.lettuce.core.SocketOptions;
 import io.lettuce.core.TimeoutOptions;
@@ -163,12 +164,35 @@ private void applyProperties(LettuceClientConfiguration.LettuceClientConfigurati
 			if (lettuce.getShutdownTimeout() != null && !lettuce.getShutdownTimeout().isZero()) {
 				builder.shutdownTimeout(getProperties().getLettuce().getShutdownTimeout());
 			}
+			String readFrom = lettuce.getReadFrom();
+			if (readFrom != null) {
+				builder.readFrom(getReadFrom(readFrom));
+			}
 		}
 		if (StringUtils.hasText(getProperties().getClientName())) {
 			builder.clientName(getProperties().getClientName());
 		}
 	}
 
+	private ReadFrom getReadFrom(String readFrom) {
+		int index = readFrom.indexOf(':');
+		if (index == -1) {
+			return ReadFrom.valueOf(getCanonicalReadFromName(readFrom));
+		}
+		String name = getCanonicalReadFromName(readFrom.substring(0, index));
+		String value = readFrom.substring(index + 1);
+		return ReadFrom.valueOf(name + ":" + value);
+	}
+
+	private String getCanonicalReadFromName(String name) {
+		StringBuilder canonicalName = new StringBuilder(name.length());
+		name.chars()
+			.filter(Character::isLetterOrDigit)
+			.map(Character::toLowerCase)
+			.forEach((c) -> canonicalName.append((char) c));
+		return canonicalName.toString();
+	}
+
 	private ClientOptions createClientOptions(
 			ObjectProvider<LettuceClientOptionsBuilderCustomizer> clientConfigurationBuilderCustomizers) {
 		ClientOptions.Builder builder = initializeClientOptionsBuilder();

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/data/redis/RedisProperties.java

@@ -467,6 +467,11 @@ public static class Lettuce {
 		 */
 		private Duration shutdownTimeout = Duration.ofMillis(100);
 
+		/**
+		 * Defines from which Redis nodes data is read.
+		 */
+		private String readFrom;
+
 		/**
 		 * Lettuce pool configuration.
 		 */
@@ -482,6 +487,14 @@ public void setShutdownTimeout(Duration shutdownTimeout) {
 			this.shutdownTimeout = shutdownTimeout;
 		}
 
+		public void setReadFrom(String readFrom) {
+			this.readFrom = readFrom;
+		}
+
+		public String getReadFrom() {
+			return this.readFrom;
+		}
+
 		public Pool getPool() {
 			return this.pool;
 		}

spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -2924,6 +2924,52 @@
         }
       ]
     },
+    {
+      "name": "spring.data.redis.lettuce.read-from",
+      "values": [
+        {
+          "value": "any",
+          "description": "Read from any node."
+        },
+        {
+          "value": "any-replica",
+          "description": "Read from any replica node."
+        },
+        {
+          "value": "lowest-latency",
+          "description": "Read from the node with the lowest latency during topology discovery."
+        },
+        {
+          "value": "regex:",
+          "description": "Read from any node that has RedisURI matching with the given pattern."
+        },
+        {
+          "value": "replica",
+          "description": "Read from the replica only."
+        },
+        {
+          "value": "replica-preferred",
+          "description": "Read preferred from replica and fall back to upstream if no replica is available."
+        },
+        {
+          "value": "subnet:",
+          "description": "Read from any node in the subnets."
+        },
+        {
+          "value": "upstream",
+          "description": "Read from the upstream only."
+        },
+        {
+          "value": "upstream-preferred",
+          "description": "Read preferred from the upstream and fall back to a replica if the upstream is not available."
+        }
+      ],
+      "providers": [
+        {
+          "name": "any"
+        }
+      ]
+    },
     {
       "name": "spring.datasource.data",
       "providers": [

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/redis/RedisAutoConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,20 +19,30 @@
 import java.time.Duration;
 import java.util.Arrays;
 import java.util.EnumSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import io.lettuce.core.ClientOptions;
+import io.lettuce.core.ReadFrom;
+import io.lettuce.core.ReadFrom.Nodes;
+import io.lettuce.core.RedisURI;
 import io.lettuce.core.cluster.ClusterClientOptions;
 import io.lettuce.core.cluster.ClusterTopologyRefreshOptions.RefreshTrigger;
+import io.lettuce.core.cluster.models.partitions.RedisClusterNode;
+import io.lettuce.core.models.role.RedisNodeDescription;
 import io.lettuce.core.resource.DefaultClientResources;
 import io.lettuce.core.tracing.Tracing;
 import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.EnabledForJreRange;
 import org.junit.jupiter.api.condition.JRE;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.autoconfigure.data.redis.RedisProperties.Pool;
@@ -112,6 +122,60 @@ void testOverrideRedisConfiguration() {
 			});
 	}
 
+	@ParameterizedTest(name = "{0}")
+	@MethodSource
+	void shouldConfigureLettuceReadFromProperty(String type, ReadFrom readFrom) {
+		this.contextRunner.withPropertyValues("spring.data.redis.lettuce.read-from:" + type).run((context) -> {
+			LettuceConnectionFactory factory = context.getBean(LettuceConnectionFactory.class);
+			LettuceClientConfiguration configuration = factory.getClientConfiguration();
+			assertThat(configuration.getReadFrom()).hasValue(readFrom);
+		});
+	}
+
+	static Stream<Arguments> shouldConfigureLettuceReadFromProperty() {
+		return Stream.of(Arguments.of("any", ReadFrom.ANY), Arguments.of("any-replica", ReadFrom.ANY_REPLICA),
+				Arguments.of("lowest-latency", ReadFrom.LOWEST_LATENCY), Arguments.of("replica", ReadFrom.REPLICA),
+				Arguments.of("replica-preferred", ReadFrom.REPLICA_PREFERRED),
+				Arguments.of("upstream", ReadFrom.UPSTREAM),
+				Arguments.of("upstream-preferred", ReadFrom.UPSTREAM_PREFERRED));
+	}
+
+	@Test
+	void shouldConfigureLettuceRegexReadFromProperty() {
+		RedisClusterNode node1 = createRedisNode("redis-node-1.region-1.example.com");
+		RedisClusterNode node2 = createRedisNode("redis-node-2.region-1.example.com");
+		RedisClusterNode node3 = createRedisNode("redis-node-1.region-2.example.com");
+		RedisClusterNode node4 = createRedisNode("redis-node-2.region-2.example.com");
+		this.contextRunner.withPropertyValues("spring.data.redis.lettuce.read-from:regex:.*region-1.*")
+			.run((context) -> {
+				LettuceConnectionFactory factory = context.getBean(LettuceConnectionFactory.class);
+				LettuceClientConfiguration configuration = factory.getClientConfiguration();
+				assertThat(configuration.getReadFrom()).hasValueSatisfying((readFrom) -> {
+					List<RedisNodeDescription> result = readFrom.select(new RedisNodes(node1, node2, node3, node4));
+					assertThat(result).hasSize(2).containsExactly(node1, node2);
+				});
+			});
+	}
+
+	@Test
+	void shouldConfigureLettuceSubnetReadFromProperty() {
+		RedisClusterNode nodeInSubnetIpv4 = createRedisNode("192.0.2.1");
+		RedisClusterNode nodeNotInSubnetIpv4 = createRedisNode("198.51.100.1");
+		RedisClusterNode nodeInSubnetIpv6 = createRedisNode("2001:db8:abcd:0000::1");
+		RedisClusterNode nodeNotInSubnetIpv6 = createRedisNode("2001:db8:abcd:1000::");
+		this.contextRunner
+			.withPropertyValues("spring.data.redis.lettuce.read-from:subnet:192.0.2.0/24,2001:db8:abcd:0000::/52")
+			.run((context) -> {
+				LettuceConnectionFactory factory = context.getBean(LettuceConnectionFactory.class);
+				LettuceClientConfiguration configuration = factory.getClientConfiguration();
+				assertThat(configuration.getReadFrom()).hasValueSatisfying((readFrom) -> {
+					List<RedisNodeDescription> result = readFrom.select(new RedisNodes(nodeInSubnetIpv4,
+							nodeNotInSubnetIpv4, nodeInSubnetIpv6, nodeNotInSubnetIpv6));
+					assertThat(result).hasSize(2).containsExactly(nodeInSubnetIpv4, nodeInSubnetIpv6);
+				});
+			});
+	}
+
 	@Test
 	void testCustomizeClientResources() {
 		Tracing tracing = mock(Tracing.class);
@@ -632,6 +696,32 @@ private String getUserName(LettuceConnectionFactory factory) {
 		return ReflectionTestUtils.invokeMethod(factory, "getRedisUsername");
 	}
 
+	private RedisClusterNode createRedisNode(String host) {
+		RedisClusterNode node = new RedisClusterNode();
+		node.setUri(RedisURI.Builder.redis(host).build());
+		return node;
+	}
+
+	private static final class RedisNodes implements Nodes {
+
+		private final List<RedisNodeDescription> descriptions;
+
+		RedisNodes(RedisNodeDescription... descriptions) {
+			this.descriptions = List.of(descriptions);
+		}
+
+		@Override
+		public List<RedisNodeDescription> getNodes() {
+			return this.descriptions;
+		}
+
+		@Override
+		public Iterator<RedisNodeDescription> iterator() {
+			return this.descriptions.iterator();
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomConfiguration {