Separate type customization from additional DataSource configuration

Closes gh-43054

Author: wilkinsona

spring-boot-project/spring-boot-docs/src/docs/asciidoc/howto/data-access.adoc

@@ -52,10 +52,15 @@ The following example shows how to define a JDBC data source by setting properti
 	    pool-size: 30
 ----
 
-However, there is a catch.
-Because the actual type of the connection pool is not exposed, no keys are generated in the metadata for your custom `DataSource` and no completion is available in your IDE (because the `DataSource` interface exposes no properties).
-Also, if you happen to have Hikari on the classpath, this basic setup does not work, because Hikari has no `url` property (but does have a `jdbcUrl` property).
-In that case, you must rewrite your configuration as follows:
+However, there is a catch due to the method's `DataSource` return type.
+This hides the actual type of the connection pool so no configuration property metadata is generated for your custom `DataSource` and no auto-completion is available in your IDE.
+To address this problem, use the builder's `type(Class)` method to specify the type of `DataSource` to be built and update the method's return type.
+For example, the following shows how to create a `HikariDataSource` with `DataSourceBuilder`:
+
+include::code:simple/MyDataSourceConfiguration[]
+
+Unfortunately, this basic setup does not work because Hikari has no `url` property.
+Instead, it has a `jdbc-url` property which means that you must rewrite your configuration as follows:
 
 [source,yaml,indent=0,subs="verbatim",configblocks]
 ----
@@ -67,22 +72,15 @@ In that case, you must rewrite your configuration as follows:
 	    pool-size: 30
 ----
 
-You can fix that by forcing the connection pool to use and return a dedicated implementation rather than `DataSource`.
-You cannot change the implementation at runtime, but the list of options will be explicit.
-
-The following example shows how to create a `HikariDataSource` with `DataSourceBuilder`:
-
-include::code:simple/MyDataSourceConfiguration[]
-
-You can even go further by leveraging what `DataSourceProperties` does for you -- that is, by providing a default embedded database with a sensible username and password if no URL is provided.
-You can easily initialize a `DataSourceBuilder` from the state of any `DataSourceProperties` object, so you could also inject the DataSource that Spring Boot creates automatically.
-However, that would split your configuration into two namespaces: `url`, `username`, `password`, `type`, and `driver` on `spring.datasource` and the rest on your custom namespace (`app.datasource`).
-To avoid that, you can redefine a custom `DataSourceProperties` on your custom namespace, as shown in the following example:
+To address this problem, make use of `DataSourceProperties` which will handle the `url` to `jdbc-url` translation for you.
+You can initialize a `DataSourceBuilder` from the state of any `DataSourceProperties` object using its `initializeDataSourceBuilder()` method.
+You could inject the `DataSourceProperties` that Spring Boot creates automatically, however, that would split your configuration across `+spring.datasource.*+` and `+app.datasource.*+`.
+To avoid this, define a custom `DataSourceProperties` with a custom configuration properties prefix, as shown in the following example:
 
 include::code:configurable/MyDataSourceConfiguration[]
 
-This setup puts you _in sync_ with what Spring Boot does for you by default, except that a dedicated connection pool is chosen (in code) and its settings are exposed in the `app.datasource.configuration` sub namespace.
-Because `DataSourceProperties` is taking care of the `url`/`jdbcUrl` translation for you, you can configure it as follows:
+This setup is equivalent to what Spring Boot does for you by default, except that the pool's type is specified in code and its settings are exposed as `app.datasource.configuration.*` properties.
+`DataSourceProperties` takes care of the `url` to `jdbc-url` translation, so you can configure it as follows:
 
 [source,yaml,indent=0,subs="verbatim",configblocks]
 ----
@@ -95,13 +93,16 @@ Because `DataSourceProperties` is taking care of the `url`/`jdbcUrl` translation
 	      maximum-pool-size: 30
 ----
 
+Note that, as the custom configuration specifies in code that Hikari should be used, `app.datasource.type` will have no effect.
+
+As described in "`<<data#data.sql.datasource.connection-pool>>`", `DataSourceBuilder` supports several different connection pools.
+To use a pool other than Hikari, add it to the classpath, use the `type(Class)` method to specify the pool class to use, and update the `@Bean` method's return type to match.
+This will also provide you with configuration property metadata for the specific connection pool that you've chosen.
+
 TIP: Spring Boot will expose Hikari-specific settings to `spring.datasource.hikari`.
 This example uses a more generic `configuration` sub namespace as the example does not support multiple datasource implementations.
 
-NOTE: Because your custom configuration chooses to go with Hikari, `app.datasource.type` has no effect.
-In practice, the builder is initialized with whatever value you might set there and then overridden by the call to `.type()`.
-
-See "`<<data#data.sql.datasource>>`" in the "`Spring Boot features`" section and the {spring-boot-autoconfigure-module-code}/jdbc/DataSourceAutoConfiguration.java[`DataSourceAutoConfiguration`] class for more details.
+See "`<<data#data.sql.datasource>>`" and the {spring-boot-autoconfigure-module-code}/jdbc/DataSourceAutoConfiguration.java[`DataSourceAutoConfiguration`] class for more details.
 
 
 
@@ -142,9 +143,12 @@ You can apply the same concept to the secondary `DataSource` as well, as shown i
 
 include::code:MyCompleteDataSourcesConfiguration[]
 
-The preceding example configures two data sources on custom namespaces with the same logic as Spring Boot would use in auto-configuration.
+The preceding example configures two data sources on custom configuration property namespaces with the same logic as Spring Boot would use in auto-configuration.
 Note that each `configuration` sub namespace provides advanced settings based on the chosen implementation.
 
+As with <<#howto.data-access.configure-custom-datasource,configuring a single custom `DataSource`>>, the type of one or both of the `DataSource` beans can be customized using the `type(Class)` method on `DataSourceBuilder`.
+See "`<<data#data.sql.datasource.connection-pool>>`" for details of the supported types.
+
 
 
 [[howto.data-access.spring-data-repositories]]

spring-boot-project/spring-boot-docs/src/docs/asciidoc/howto/testing.adoc

@@ -33,7 +33,7 @@ include::{docs-java}/howto/testing/slicetests/MyConfiguration.java[]
 For a `@WebMvcTest` for an application with the above `@Configuration` class, you might expect to have the `SecurityFilterChain` bean in the application context so that you can test if your controller endpoints are secured properly.
 However, `MyConfiguration` is not picked up by @WebMvcTest's component scanning filter because it doesn't match any of the types specified by the filter.
 You can include the configuration explicitly by annotating the test class with `@Import(MyConfiguration.class)`.
-This will load all the beans in `MyConfiguration` including the `BasicDataSource` bean which isn't required when testing the web tier.
+This will load all the beans in `MyConfiguration` including the `HikariDataSource` bean which isn't required when testing the web tier.
 Splitting the configuration class into two will enable importing just the security configuration.
 
 [source,java,indent=0,subs="verbatim"]

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/dataaccess/configuretwodatasources/MyCompleteDataSourcesConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -17,7 +17,6 @@
 package org.springframework.boot.docs.howto.dataaccess.configuretwodatasources;
 
 import com.zaxxer.hikari.HikariDataSource;
-import org.apache.commons.dbcp2.BasicDataSource;
 
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
@@ -51,9 +50,9 @@ public DataSourceProperties secondDataSourceProperties() {
 
 	@Bean
 	@ConfigurationProperties("app.datasource.second.configuration")
-	public BasicDataSource secondDataSource(
+	public HikariDataSource secondDataSource(
 			@Qualifier("secondDataSourceProperties") DataSourceProperties secondDataSourceProperties) {
-		return secondDataSourceProperties.initializeDataSourceBuilder().type(BasicDataSource.class).build();
+		return secondDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
 	}
 
 }

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/dataaccess/configuretwodatasources/MyDataSourcesConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -17,7 +17,6 @@
 package org.springframework.boot.docs.howto.dataaccess.configuretwodatasources;
 
 import com.zaxxer.hikari.HikariDataSource;
-import org.apache.commons.dbcp2.BasicDataSource;
 
 import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
 import org.springframework.boot.context.properties.ConfigurationProperties;
@@ -45,8 +44,8 @@ public HikariDataSource firstDataSource(DataSourceProperties firstDataSourceProp
 
 	@Bean
 	@ConfigurationProperties("app.datasource.second")
-	public BasicDataSource secondDataSource() {
-		return DataSourceBuilder.create().type(BasicDataSource.class).build();
+	public HikariDataSource secondDataSource() {
+		return DataSourceBuilder.create().type(HikariDataSource.class).build();
 	}
 
 }

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/testing/slicetests/MyConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -16,7 +16,7 @@
 
 package org.springframework.boot.docs.howto.testing.slicetests;
 
-import org.apache.commons.dbcp2.BasicDataSource;
+import com.zaxxer.hikari.HikariDataSource;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.jdbc.DataSourceBuilder;
@@ -36,8 +36,8 @@ public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Excepti
 
 	@Bean
 	@ConfigurationProperties("app.datasource.second")
-	public BasicDataSource secondDataSource() {
-		return DataSourceBuilder.create().type(BasicDataSource.class).build();
+	public HikariDataSource secondDataSource() {
+		return DataSourceBuilder.create().type(HikariDataSource.class).build();
 	}
 
 }

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/howto/testing/slicetests/MyDatasourceConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -16,7 +16,7 @@
 
 package org.springframework.boot.docs.howto.testing.slicetests;
 
-import org.apache.commons.dbcp2.BasicDataSource;
+import com.zaxxer.hikari.HikariDataSource;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.jdbc.DataSourceBuilder;
@@ -28,8 +28,8 @@ public class MyDatasourceConfiguration {
 
 	@Bean
 	@ConfigurationProperties("app.datasource.second")
-	public BasicDataSource secondDataSource() {
-		return DataSourceBuilder.create().type(BasicDataSource.class).build();
+	public HikariDataSource secondDataSource() {
+		return DataSourceBuilder.create().type(HikariDataSource.class).build();
 	}
 
 }

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/howto/dataaccess/configuretwodatasources/MyCompleteDataSourcesConfiguration.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -17,7 +17,6 @@
 package org.springframework.boot.docs.howto.dataaccess.configuretwodatasources
 
 import com.zaxxer.hikari.HikariDataSource
-import org.apache.commons.dbcp2.BasicDataSource
 import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties
 import org.springframework.boot.context.properties.ConfigurationProperties
 import org.springframework.context.annotation.Bean
@@ -49,8 +48,8 @@ class MyCompleteDataSourcesConfiguration {
 
 	@Bean
 	@ConfigurationProperties("app.datasource.second.configuration")
-	fun secondDataSource(secondDataSourceProperties: DataSourceProperties): BasicDataSource {
-		return secondDataSourceProperties.initializeDataSourceBuilder().type(BasicDataSource::class.java).build()
+	fun secondDataSource(secondDataSourceProperties: DataSourceProperties): HikariDataSource {
+		return secondDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource::class.java).build()
 	}
 
 }

spring-boot-project/spring-boot-docs/src/main/kotlin/org/springframework/boot/docs/howto/dataaccess/configuretwodatasources/MyDataSourcesConfiguration.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -17,7 +17,6 @@
 package org.springframework.boot.docs.howto.dataaccess.configuretwodatasources
 
 import com.zaxxer.hikari.HikariDataSource
-import org.apache.commons.dbcp2.BasicDataSource
 import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties
 import org.springframework.boot.context.properties.ConfigurationProperties
 import org.springframework.boot.jdbc.DataSourceBuilder
@@ -44,8 +43,8 @@ class MyDataSourcesConfiguration {
 
 	@Bean
 	@ConfigurationProperties("app.datasource.second")
-	fun secondDataSource(): BasicDataSource {
-		return DataSourceBuilder.create().type(BasicDataSource::class.java).build()
+	fun secondDataSource(): HikariDataSource {
+		return DataSourceBuilder.create().type(HikariDataSource::class.java).build()
 	}
 
 }

spring-boot-project/spring-boot-docs/src/test/java/org/springframework/boot/docs/howto/dataaccess/configuretwodatasources/MyDataSourcesConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -20,7 +20,7 @@
 
 import javax.sql.DataSource;
 
-import org.apache.commons.dbcp2.BasicDataSource;
+import com.zaxxer.hikari.HikariDataSource;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 
@@ -38,8 +38,8 @@
  * @author Stephane Nicoll
  */
 @ExtendWith(SpringExtension.class)
-@SpringBootTest(properties = { "app.datasource.second.url=jdbc:h2:mem:bar;DB_CLOSE_DELAY=-1",
-		"app.datasource.second.max-total=42" })
+@SpringBootTest(properties = { "app.datasource.second.jdbc-url=jdbc:h2:mem:bar;DB_CLOSE_DELAY=-1",
+		"app.datasource.second.maximum-pool-size=42" })
 @Import(MyDataSourcesConfiguration.class)
 class MyDataSourcesConfigurationTests {
 
@@ -52,9 +52,9 @@ void validateConfiguration() throws SQLException {
 		DataSource dataSource = this.context.getBean(DataSource.class);
 		assertThat(this.context.getBean("firstDataSource")).isSameAs(dataSource);
 		assertThat(dataSource.getConnection().getMetaData().getURL()).startsWith("jdbc:h2:mem:");
-		BasicDataSource secondDataSource = this.context.getBean("secondDataSource", BasicDataSource.class);
-		assertThat(secondDataSource.getUrl()).isEqualTo("jdbc:h2:mem:bar;DB_CLOSE_DELAY=-1");
-		assertThat(secondDataSource.getMaxTotal()).isEqualTo(42);
+		HikariDataSource secondDataSource = this.context.getBean("secondDataSource", HikariDataSource.class);
+		assertThat(secondDataSource.getJdbcUrl()).isEqualTo("jdbc:h2:mem:bar;DB_CLOSE_DELAY=-1");
+		assertThat(secondDataSource.getMaximumPoolSize()).isEqualTo(42);
 	}
 
 }