Spring Boot 2.5 Release Notes - spring-projects/spring-boot Wiki

Spring Boot 2.5 Release Notes

Upgrading from Spring Boot 2.4

SQL Script DataSource Initialization

The underlying method used to support schema.sql and data.sql scripts has been redesigned in Spring Boot 2.5. spring.datasource.* properties related to DataSource initialization have been deprecated in favor of new spring.sql.init.* properties. These properties can also be used to initialize an SQL database accessed via R2DBC.

schema.sql and data.sql Files

With Spring Boot 2.5.1 and above, the new SQL initialization properties support detection of embedded datasources for JDBC and R2DBC. By default, SQL database initialization is only performed when using an embedded in-memory database. To always initialize a SQL database, irrespective of its type, set spring.sql.init.mode to always. Similarly, to disable initialization, set spring.sql.init.mode to never.

Separate Credentials

The new script-based SQL database initialization does not support using separate credentials for schema (DDL) and data (DML) changes. This reduces complexity and aligns its capabilities with Flyway and Liquibase. If you require separate credentials for schema and data initialization, define your own org.springframework.jdbc.datasource.init.DataSourceInitializer beans.

Hibernate and data.sql

By default, data.sql scripts are now run before Hibernate is initialized. This aligns the behavior of basic script-based initialization with that of Flyway and Liquibase. If you want to use data.sql to populate a schema created by Hibernate, set spring.jpa.defer-datasource-initialization to true. While mixing database initialization technologies is not recommended, this will also allow you to use a schema.sql script to build upon a Hibernate-created schema before it’s populated via data.sql.

Initialization ordering

Beans of certain well-known types, such as JdbcTemplate, will be ordered so that they are initialized after the database has been initialized. If you have a bean that works with the DataSource directly, annotate its class or @Bean method with @DependsOnDatabaseInitialization to ensure that it too is initialized after the database has been initialized.

Flyway and Liquibase JDBC URLs

If you currently define a spring.flyway.url or spring.liquibase.url you may need to provide additional username and password properties. In earlier versions of Spring Boot, these settings were derived from spring.datasource properties but this turned out to be problematic for people that provided their own DataSource beans.

Spring Data JPA

Spring Data JPA introduces a new getById method which replaces getOne. If you find your application is now throwing a LazyLoadingException please rename any existing getById method to getXyzById (where xyz is an arbitrary string). For more details, please read the updated Spring Data JPA reference documentation.

Spring Data Solr

Following its removal from Spring Data in 2021.0.0, auto-configuration for Spring Data Solr has been removed in this release.

Secure Info Endpoint

The /info actuator endpoint is no longer exposed over the web by default. Additionally, if Spring Security is on the classpath and your application doesn’t have a custom security configuration, the endpoint requires authenticated access by default.

Refer to the documentation on exposing and securing actuator endpoints to change these new defaults.

Task Scheduling Harmonization with Spring Integration

Spring Integration now reuses an available TaskScheduler rather that configuring its own. In a typical application setup relying on the auto-configuration, this means that Spring Integration uses the auto-configured task scheduler that has a pool size of 1. To restore Spring Integration’s default of 10 threads, use the spring.task.scheduling.pool.size property.

Default Expression Language (EL) Implementation

The EL implementation that is included in Spring Boot’s web and validation starters has changed. Tomcat’s implementation (org.apache.tomcat.embed.tomcat-embed-el) is now used in place of the reference implementation from Glassfish (org.glassfish:jakrta.el).

Messages in the Default Error View

The message attribute in the default error view is now removed rather than blanked when it is not shown. If you parse the error response JSON, you may need to deal with the missing item.

You can still use the server.error.include-message property if you want messages to be included.

Logging Shutdown Hooks

We now register a logging shutdown hook by default for jar based applications to ensure that logging resources are released when the JVM exits. If your application is deployed as a war then the shutdown hook is not registered since the servlet container usually handles logging concerns.

Most applications will want the shutdown hook. However, if your application has complex context hierarchies, then you may need to disable it. You can use the logging.register-shutdown-hook property to do that.

Gradle Default jar and war Tasks

The Spring Boot Gradle Plugin no longer automatically disables the standard Gradle jar and war tasks. Instead we now apply a classifier to those tasks.

If you prefer to disable those tasks, the reference documentation includes updated examples.

Cassandra Throttling Properties

Spring Boot no longer provides default values for spring.data.cassandra.request.throttler properties. If you rely on max-queue-size, max-concurrent-requests, max-requests-per-second or drain-interval you should set values that make sense for your application.

Customizing jOOQ’s DefaultConfiguration

To streamline the customization of jOOQ’s DefaultConfiguration, a bean that implements DefaultConfigurationCustomizer can now be defined. This customiser callback should be used in favour of defining one or more *Provider beans, the support for which has now been deprecated.

Groovy 3

The default version of Groovy has been upgraded to 3.x. If you are using Groovy and also using Spock, you should also upgrade to the latest Groovy 3.0-compatible release of Spock 2.0. Alternatively, use the groovy.version to downgrade back to Groovy 2.5.

Minimum Requirements Changes

Projects built with Gradle now require Gradle 6.8 or later.

Hibernate Validator 6.2

The default version of Hibernate Validate has been upgraded to 6.2.x. Hibernate Validator 6.2 changes how the expression language is used to interpolate constraint messages. Please see this blog post from the Hibernate Validator team for further details.

Deprecations from Spring Boot 2.3 and 2.4

Reflecting the Spring Boot release compatibility policy, code deprecated in Spring Boot 2.3 has been removed in Spring Boot 2.5. Code deprecated in Spring Boot 2.4 remains in place, and is scheduled for removal in Spring Boot 2.6.

New and Noteworthy

Tip
Check the configuration changelog for a complete overview of the changes in configuration.

Environment Variable Prefixes

It’s now possible to specify a prefix for system environment variables so that you can run multiple different Spring Boot applications in the same environment. Use SpringApplication.setEnvironmentPrefix(…​) to set the prefix that you want to use when binding properties.

For example, the following will add a myapp prefix:

SpringApplication application = new SpringApplication(MyApp.class);
application.setEnvironmentPrefix("myapp");
application.run(args);

All properties will now expect a prefixed version. For example, to change the server port you can set MYAPP_SERVER_PORT.

HTTP/2 over TCP (h2c)

All four embedded web containers now support HTTP/2 over TCP (h2c) without any manual customization. To enable h2c, set server.http2.enabled is true and leave server.ssl.enabled set to false (its default value).

As with the existing h2 support, depending on the embedded web server being used, the use of h2c may require additional dependencies. See the reference documentation for details.

Generic DataSource Initialization

A new generic mechanism is now available if you write code that initializes a DataSource. This mechanism is also now used internally to setup correct bean dependencies for Flyway, Liquibase and Script based initialization.

Most developers won’t need to directly make use of the new mechanism. However, if you are developing a third-party starter for a data access library, you may want to provide a DependsOnDataSourceInitializationDetector. See the updated reference documentation for details.

Database Initialization with R2DBC

Support for script-based initialization of an SQL database accessed via R2DBC has been added. By default, scripts on the classpath named schema.sql and data.sql will be applied to the database automatically. The initialization can be customized using the spring.sql.init.* configuration properties. Please see the reference documentation for further details.

Liquibase DataSource

If you define a custom DataSource for use with Liquibase we now configure it using a SimpleDriverDataSource. We previously used a pooling datasource which was unnecessary and inefficient for database initialization.

Layered WARs

The Spring Boot Maven and Gradle plugins now allow you to create layered WARs for use with Docker images. Layered WARs work in a similar way to the Layered JAR support that was provided in earlier versions of Spring Boot. Check out the Gradle and Maven reference documentation for more details.

Docker Image Building Support

Custom Buildpacks

The Maven and Gradle plugins both now support the use of custom Buildpacks. You can set the buildpacks property to point at directories, tar.gz files, specific builder references or Docker images.

See the updated Gradle and Maven reference documentation for more details.

Bindings

The Maven and Gradle plugins now both support volume bindings that can be passed to the buildpack builder. These allow you to bind local paths or volumes for the buildpack to use.

See the updated Gradle and Maven reference documentation for more details.

War Support

Both the Maven and Gradle plugin can now package executable war files into Docker images. The existing mvn spring-boot:image or ./gradlew bootBuildImage commands should be used if you want to create a Docker image for your war.

OpenMetrics for Prometheus

The /actuator/prometheus actuator endpoint can now provide both standard Prometheus as well as OpenMetrics responses. The response returned will depend on the accept header that is provided with the HTTP request.

Metrics for Spring Data Repositories

Actuator will now generate Micrometer metrics for Spring Data repositories. By default, metrics are named spring.data.repository.invocations. To learn more, please see the relevant section of the reference documentation.

@Timed Metrics with WebFlux

Aligning its capabilities with those of Spring MVC, @Timed can now be used to manually enable timing of requests handled by WebFlux controllers and functional handlers. To use manual timing, set management.metrics.web.server.request.autotime.enabled to false.

MongoDB Metrics

When using Actuator, metrics for Mongo’s connection pool and commands sent by the client are now generated automatically. To learn more about MongoDB metrics, please see the relevant section of the reference documentation.

Actuator Endpoint for Quartz

A /quartz endpoint has been added to Actuator. It provides detailed information about Quartz jobs and triggers. Please see the relevant section of the Actuator’s API documentation for further details.

GET requests to actuator/startup

The actuator’s startup endpoint now supports GET requests. Unlike a POST request, a GET request to the endpoint does not drain the event buffer and events will continue to be held in memory.

Abstract Routing DataSource Health

Actuator’s health endpoint now shows the health of the targets of an AbstractRoutingDataSource. Each target DataSource is named using its routing key. As before, to ignore routing data sources in the health endpoint, set management.health.db.ignore-routing-data-sources to true.

Java 16 Support

This release provides support and is tested against Java 16. Spring Boot 2.5 remains compatible with Java 8.

Gradle 7 Support

The Spring Boot Gradle plugin supports and is tested against Gradle 7.0.x.

Jetty 10 Support

Spring Boot 2.5 can now use Jetty 10 as an embedded web server. As Jetty 10 requires Java 11, our default Jetty version will remain as 9.

To upgrade to Jetty 10, use the jetty.version property to override the version. You should also exclude org.eclipse.jetty.websocket:websocket-server and org.eclipse.jetty.websocket:javax-websocket-server-impl from spring-boot-starter-jetty as they are Jetty 9-specific.

Documentation Updates

The HTML documentation published by the project has an updated look-and-feel and some new features. You can now easily copy snippets of code to the clipboard by hovering over the sample and clicking the "copy" icon. In addition, many of the samples now include full import statements that can be shown or hidden as required.

We also now have a "dark theme" switcher at the top of each document.

Miscellaneous

Apart from the changes listed above, there have also been lots of minor tweaks and improvements including:

  • management.endpoints.web.cors.allowed-origin-patterns can now be used to configure the allowed origin patterns for Actuator endpoints (#24608)

  • HttpSessionIdListener beans are now automatically registered with the servlet context (#24879)

  • Couchbase now uses the auto-configured ObjectMapper by default (#24616)

  • Elasticsearch’s Sniffer is now auto-configured when its elasticsearch-rest-client-sniffer module is on the classpath (#24174)

  • spring.data.cassandra.controlconnection.timeout can now be used to configure the timeout of Cassandra’s control connection (#24189)

  • spring.kafka.listener.only-log-record-metadata can now be used to configure what’s logged when retries are being attempted (#24582)

  • Support for Apache Phoenix, auto-detecting jdbc:phoenix JDBC URLs (#24114)

  • Configuration properties for Rabbit’s key store and trust store algorithms (#24076)

  • The /actuator discovery page can now be disabled using the management.endpoints.web.discovery.enabled property.

  • The /actuator/configprops and actuator/env endpoints now have additional-keys-to-sanitize properties that can be used to sanitize keys.

  • You can now use a EndpointObjectNameFactory if you want to customize the name of JMX actuator endpoints.

  • A new DataSourceBuilder.derivedFrom(…​) method has been added that allows you to build a new DataSource that’s derived from an existing one.

  • When Spring Security is on the classpath, configuration properties can now be bound to RSAPublicKey and RSAPrivateKey.

  • The RabbitMQ ConnectionFactory used by Spring AMQP can now be customized using a ConnectionFactoryCustomizer bean.

  • Embedded database auto-configured can now be controlled using the new spring.datasource.embedded-database-connection configuration property. It can be set to any of the values of EmbeddedDatabaseConnection, including none to disable embedded database auto-configured entirely.

  • CloudPlatform can now automatically detect Azure App Service.

  • server.tomcat.keep-alive-timeout can be used to configure how long Tomcat will wait for another request before closing a keep-alive connection.

  • server.tomcat.max-keep-alive-requests can be used to control the maximum number of requests that can be made on a keep-alive connection before it is closed.

  • spring.webflux.session.cookie.same-site can be used to configure WebFlux’s SameSite cookie policy. It is lax by default.

  • Apache HttpClient 5 is now auto-configured for use with WebClient.

  • A new ApplicationEnvironment class has been introduced which should improve a small performance boost.

  • You can now configure Netty memory using the spring.netty.leak-detection property.

Dependency Upgrades

Spring Boot 2.5 moves to new versions of several Spring projects:

Numerous third-party dependencies have also been updated, some of the more noteworthy of which are the following:

  • Kotlin 1.5

  • Groovy 3.0

  • Flyway 7.7

  • Liquibase 4.3

  • Jackson 2.12

  • Kafka 2.7

  • Cassandra Driver 4.10

  • Embedded Mongo 3.0

  • Hibernate Validator 6.2

  • Jersey 2.33

  • Mockito 3.7

  • MongoDB 4.2

  • JUnit Jupiter 5.7

  • Elasticsearch 7.12

Notable Deprecations in Spring Boot 2.5

The following notable deprecations have been made in Spring Boot 2.5

  • ActuatorMediaType and ApiVersion in org.springframework.boot.actuate.endpoint.http in favor of equivalents in org.springframework.boot.actuate.endpoint

  • Support for beans that implement jOOQ’s *Provider callback interfaces or Settings has been deprecated. A DefaultConfigurationCustomizer should be used instead.

  • EntityManagerFactoryDependsOnPostProcessor in org.springframework.boot.autoconfigure.data.jpa has been relocated to org.springframework.boot.autoconfigure.orm.jpa

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