Merge pull request #44366 from nosan

* pr/44366:
  Add spring.data.mongodb.protocol property

Closes gh-44366

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

@@ -51,6 +51,11 @@ public class MongoProperties {
 	 */
 	public static final String DEFAULT_URI = "mongodb://localhost/test";
 
+	/**
+	 * Protocol to be used for the MongoDB connection. Ignored if 'uri' is set.
+	 */
+	private String protocol = "mongodb";
+
 	/**
 	 * Mongo server host. Ignored if 'uri' is set.
 	 */
@@ -117,6 +122,14 @@ public class MongoProperties {
 	 */
 	private Boolean autoIndexCreation;
 
+	public void setProtocol(String protocol) {
+		this.protocol = protocol;
+	}
+
+	public String getProtocol() {
+		return this.protocol;
+	}
+
 	public String getHost() {
 		return this.host;
 	}

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

@@ -51,11 +51,11 @@ public class PropertiesMongoConnectionDetails implements MongoConnectionDetails
 
 	@Override
 	public ConnectionString getConnectionString() {
-		// mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database.collection][?options]]
+		// protocol://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database.collection][?options]]
 		if (this.properties.getUri() != null) {
 			return new ConnectionString(this.properties.getUri());
 		}
-		StringBuilder builder = new StringBuilder("mongodb://");
+		StringBuilder builder = new StringBuilder(getProtocol()).append("://");
 		if (this.properties.getUsername() != null) {
 			builder.append(encode(this.properties.getUsername()));
 			builder.append(":");
@@ -83,6 +83,14 @@ public class PropertiesMongoConnectionDetails implements MongoConnectionDetails
 		return new ConnectionString(builder.toString());
 	}
 
+	private String getProtocol() {
+		String protocol = this.properties.getProtocol();
+		if (StringUtils.hasText(protocol)) {
+			return protocol;
+		}
+		return "mongodb";
+	}
+
 	private String encode(String input) {
 		return URLEncoder.encode(input, StandardCharsets.UTF_8);
 	}

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

@@ -2924,6 +2924,22 @@
         }
       ]
     },
+    {
+      "name": "spring.data.mongodb.protocol",
+      "values": [
+        {
+          "value": "mongodb"
+        },
+        {
+          "value": "mongodb+srv"
+        }
+      ],
+      "providers": [
+        {
+          "name": "any"
+        }
+      ]
+    },
     {
       "name": "spring.data.redis.lettuce.read-from",
       "values": [

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

@@ -24,6 +24,7 @@ import com.mongodb.MongoCredential;
 import com.mongodb.client.MongoClient;
 import com.mongodb.client.MongoClients;
 import com.mongodb.client.internal.MongoClientImpl;
+import com.mongodb.connection.ClusterConnectionMode;
 import com.mongodb.connection.SslSettings;
 import org.junit.jupiter.api.Test;
 
@@ -98,6 +99,22 @@ class MongoAutoConfigurationTests {
 			});
 	}
 
+	@Test
+	void configuresProtocol() {
+		this.contextRunner.withPropertyValues("spring.data.mongodb.protocol=mongodb+srv").run((context) -> {
+			MongoClientSettings settings = getSettings(context);
+			assertThat(settings.getClusterSettings().getMode()).isEqualTo(ClusterConnectionMode.MULTIPLE);
+		});
+	}
+
+	@Test
+	void defaultProtocol() {
+		this.contextRunner.run((context) -> {
+			MongoClientSettings settings = getSettings(context);
+			assertThat(settings.getClusterSettings().getMode()).isEqualTo(ClusterConnectionMode.SINGLE);
+		});
+	}
+
 	@Test
 	void configuresWithoutSslWhenDisabledWithBundle() {
 		this.contextRunner

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

@@ -86,6 +86,13 @@ class PropertiesMongoConnectionDetailsTests {
 		assertThat(connectionString.getDatabase()).isEqualTo("test");
 	}
 
+	@Test
+	void protocolCanBeConfigured() {
+		this.properties.setProtocol("mongodb+srv");
+		ConnectionString connectionString = this.connectionDetails.getConnectionString();
+		assertThat(connectionString.getConnectionString()).startsWith("mongodb+srv://");
+	}
+
 	@Test
 	void authenticationDatabaseCanBeConfigured() {
 		this.properties.setUsername("user");