Merge pull request #32125 from thegeekyasian

* pr/32125:
  Polish 'Allow multiple hosts to be set in MongoProperties'
  Allow multiple hosts to be set in MongoProperties

Closes gh-32125

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mongo/MongoProperties.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.autoconfigure.mongo;
 
+import java.util.List;
+
 import com.mongodb.ConnectionString;
 import org.bson.UuidRepresentation;
 
@@ -33,6 +35,7 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
  * @author Nasko Vasilev
  * @author Mark Paluch
  * @author Artsiom Yudovin
+ * @author Safeer Ansari
  * @since 1.0.0
  */
 @ConfigurationProperties(prefix = "spring.data.mongodb")
@@ -58,6 +61,13 @@ public class MongoProperties {
 	 */
 	private Integer port = null;
 
+	/**
+	 * Additional server hosts. Cannot be set with URI or if 'host' is not specified.
+	 * Additional hosts will use the default mongo port of 27017, if you want to use a
+	 * different port you can use the "host:port" syntax.
+	 */
+	private List<String> additionalHosts;
+
 	/**
 	 * Mongo database URI. Overrides host, port, username, password, and database.
 	 */
@@ -208,6 +218,14 @@ public class MongoProperties {
 		this.autoIndexCreation = autoIndexCreation;
 	}
 
+	public List<String> getAdditionalHosts() {
+		return this.additionalHosts;
+	}
+
+	public void setAdditionalHosts(List<String> additionalHosts) {
+		this.additionalHosts = additionalHosts;
+	}
+
 	public static class Gridfs {
 
 		/**

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mongo/MongoPropertiesClientSettingsBuilderCustomizer.java

@@ -16,7 +16,8 @@
 
 package org.springframework.boot.autoconfigure.mongo;
 
-import java.util.Collections;
+import java.util.ArrayList;
+import java.util.List;
 
 import com.mongodb.ConnectionString;
 import com.mongodb.MongoClientSettings;
@@ -24,12 +25,14 @@ import com.mongodb.MongoCredential;
 import com.mongodb.ServerAddress;
 
 import org.springframework.core.Ordered;
+import org.springframework.util.CollectionUtils;
 
 /**
  * A {@link MongoClientSettingsBuilderCustomizer} that applies properties from a
  * {@link MongoProperties} to a {@link MongoClientSettings}.
  *
  * @author Scott Frederick
+ * @author Safeer Ansari
  * @since 2.4.0
  */
 public class MongoPropertiesClientSettingsBuilderCustomizer implements MongoClientSettingsBuilderCustomizer, Ordered {
@@ -62,8 +65,12 @@ public class MongoPropertiesClientSettingsBuilderCustomizer implements MongoClie
 		if (this.properties.getHost() != null || this.properties.getPort() != null) {
 			String host = getOrDefault(this.properties.getHost(), "localhost");
 			int port = getOrDefault(this.properties.getPort(), MongoProperties.DEFAULT_PORT);
-			ServerAddress serverAddress = new ServerAddress(host, port);
+			List<ServerAddress> serverAddresses = new ArrayList<>();
-			settings.applyToClusterSettings((cluster) -> cluster.hosts(Collections.singletonList(serverAddress)));
+			serverAddresses.add(new ServerAddress(host, port));
+			if (!CollectionUtils.isEmpty(this.properties.getAdditionalHosts())) {
+				this.properties.getAdditionalHosts().stream().map(ServerAddress::new).forEach(serverAddresses::add);
+			}
+			settings.applyToClusterSettings((cluster) -> cluster.hosts(serverAddresses));
 			return;
 		}
 		settings.applyConnectionString(new ConnectionString(MongoProperties.DEFAULT_URI));

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mongo/MongoPropertiesClientSettingsBuilderCustomizerTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.mongo;
 
+import java.util.Arrays;
 import java.util.List;
 
 import com.mongodb.MongoClientSettings;
@@ -53,6 +54,18 @@ class MongoPropertiesClientSettingsBuilderCustomizerTests {
 		assertServerAddress(allAddresses.get(0), "mongo.example.com", 27017);
 	}
 
+	@Test
+	void additionalHostCanBeAdded() {
+		this.properties.setHost("mongo.example.com");
+		this.properties.setAdditionalHosts(Arrays.asList("mongo.example.com:33", "mongo.example2.com"));
+		MongoClientSettings settings = customizeSettings();
+		List<ServerAddress> allAddresses = getAllAddresses(settings);
+		assertThat(allAddresses).hasSize(3);
+		assertServerAddress(allAddresses.get(0), "mongo.example.com", 27017);
+		assertServerAddress(allAddresses.get(1), "mongo.example.com", 33);
+		assertServerAddress(allAddresses.get(2), "mongo.example2.com", 27017);
+	}
+
 	@Test
 	void credentialsCanBeCustomized() {
 		this.properties.setUsername("user");

spring-boot-project/spring-boot-docs/src/docs/asciidoc/data/nosql.adoc

@@ -80,7 +80,7 @@ You can set the configprop:spring.data.mongodb.uri[] property to change the URL
 	spring:
 	  data:
 	    mongodb:
-	      uri: "mongodb://user:secret@mongo1.example.com:12345,mongo2.example.com:23456/test"
+	      uri: "mongodb://user:secret@mongoserver1.example.com:27017,mongoserver2.example.com:23456/test"
 ----
 
 Alternatively, you can specify connection details using discrete properties.
@@ -91,16 +91,24 @@ For example, you might declare the following settings in your `application.prope
 	spring:
 	  data:
 	    mongodb:
-	      host: "mongoserver.example.com"
+	      host: "mongoserver1.example.com"
 	      port: 27017
+	      additional-hosts:
+	      - "mongoserver2.example.com:23456"
 	      database: "test"
 	      username: "user"
 	      password: "secret"
 ----
 
-TIP: If `spring.data.mongodb.port` is not specified, the default of `27017` is used.
+[TIP]
+====
+If `spring.data.mongodb.port` is not specified, the default of `27017` is used.
 You could delete this line from the example shown earlier.
 
+You can also specify the port as part of the host address by using the `host:port` syntax.
+This format should be used if you need to change the port of an `additional-hosts` entry.
+====
+
 TIP: If you do not use Spring Data MongoDB, you can inject a `MongoClient` bean instead of using `MongoDatabaseFactory`.
 If you want to take complete control of establishing the MongoDB connection, you can also declare your own `MongoDatabaseFactory` or `MongoClient` bean.