TL;DR

This release focuses on stability improvements across Spring Boot, addressing several bug fixes related to file handling, configuration, and integrations with technologies like RabbitMQ, Cassandra, and Docker Compose.

Fixes Worth Knowing

• Fixed an issue where symlinks were not handled correctly by ApplicationPidFileWriter and ApplicationTemp.
• Resolved inconsistencies in applying spring.rabbitmq.ssl.verify-hostname.
• Corrected issues with Docker Compose support for Apache ActiveMQ and Artemis images.
• Fixed a bug where HTTP method was lost when configuring endpoint exclusions.
• Resolved an issue with incorrect comparisons in Remote DevTools (remote debugging).

Before You Upgrade

If you are using symlinks with ApplicationPidFileWriter or ApplicationTemp, verify their behavior after upgrading.

TL;DR

Spring Boot now supports Elasticsearch via docker.elastic.co/elasticsearch/elasticsearch, adding flexibility for containerized deployments.

New

• Elasticsearch Support: Added support for the official Elasticsearch Docker image.
• Kafka Configuration: New options for controlling KafkaTemplate behavior (allowNonTransactional, closeTimeout).
• Redis Listeners: Support for annotation-driven Redis message listeners has been added.

Fixes Worth Knowing

• Actuator Security: Corrected a security misconfiguration when using spring-boot-actuator-autoconfigure without spring-boot-health.
• Elasticsearch Client: Fixed misconfiguration of the underlying HTTP client in Elasticsearch auto-configuration.
• Symlink Handling: Improved handling of symbolic links for application PID and temporary files.
• RabbitMQ SSL: Consistent application of the spring.rabbitmq.ssl.verify-hostname property.

TL;DR

This release significantly improves Spring Boot’s stability by addressing numerous configuration and dependency issues across various auto-configured components, impacting users of Actuator, Elasticsearch, RabbitMQ, and database integrations.

Fixes Worth Knowing

Several fixes address common configuration problems: default security settings with Actuator, Elasticsearch client setup, and SSL hostname verification for RabbitMQ. Fixes were also made to correctly handle symlinks when writing application PID and temporary files. Additionally, issues with reactive MongoDB dependencies and HTTP method handling in endpoint exclusions have been resolved.

TL;DR

Spring Boot now supports Docker’s credential stores and helpers, enhancing security for containerized applications. Numerous dependency upgrades improve stability and bring the latest features from those ecosystems.

Breaking

• spring.codec properties have been renamed to spring.http.codecs.
• spring.http.client properties have been renamed to spring.http.client.settings.
• spring.mvc.converters.preferred-json-mapper has been renamed to spring.http.converters.preferred-json-mapper.

New

• Docker Credential Store Support: Enables secure access to Docker registries using established credential management practices.
• OtlpMetricsSender Auto-Configuration: Automatically configures OpenTelemetry Protocol (Otlp) metrics exporting if available, simplifying observability setup.

Fixes Worth Knowing

• Resolved a StackOverflowError when logging deeply nested objects using structured logging.
• Fixed an issue preventing correct SSL configuration in reactive web applications when using file-based stores.
• Corrected an NPE in Hikari when building a DataSource with an unknown JDBC driver.

Before You Upgrade

• Update your application configuration to reflect the renamed properties: spring.codec, spring.http.client, and spring.mvc.converters.preferred-json-mapper.

TL;DR

The default container image builder for bootBuildImage and spring-boot:build-image has been updated to Paketo Jammy (container building tool) due to security concerns with the previous builder.

Breaking

• The default container image builder has changed to Paketo Jammy. (Container image creation)

New

None

Fixes Worth Knowing

• Resolved a NoSuchMethodError when using Flyway 10.0.0. (Database migration tool)
• Corrected behavior for spring.webflux.multipart.max-disk-usage-per-part when values exceed integer limits. (File uploads)
• Fixed an issue preventing the mail health indicator from starting when a host isn’t configured. (Application health checks)

Before You Upgrade

• If you explicitly configured the Bionic builder, update your configuration to use Jammy.

TL;DR

Spring Boot 2.0 introduces a major upgrade to Spring Framework 6, requiring Java 17 and offering improved performance and observability features.

Breaking

• Java 8 is no longer supported (minimum Java 17).
• Dependencies have been updated to Spring Framework 6 (major version change).
• Removed support for several deprecated features.

New

• Improved observability with Micrometer Tracing (distributed tracing).
• Native image support via GraalVM (compiles to standalone executables).

Fixes Worth Knowing

• Resolved several issues related to configuration property binding.
• Addressed edge cases in auto-configuration logic.
• Fixed inconsistencies in error handling for web applications.

Before You Upgrade

• Ensure your application is running on Java 17 or later.
• Review your dependencies for compatibility with Spring Framework 6.

TL;DR

Spring Boot now supports Prometheus Exemplars and GraphQL RSocket, enhancing observability and expanding GraphQL capabilities.

Breaking

• DatabaseDriver.GAE is deprecated and will be removed in a future release. (Database connection method)
• Elasticsearch RestHighLevelClient is deprecated; use RestClientBuilder instead. (Elasticsearch client)
• Running applications in the Maven process is deprecated. (Build process)

New

• Prometheus Exemplars: Adds support for linking metrics to traces for improved debugging.
• GraphQL RSocket: Enables RSocket protocol support for GraphQL, allowing for bi-directional communication.
• TLS with PEM: Auto-configuration now supports TLS using PEM files instead of keystores. (Security certificates)

Fixes Worth Knowing

• Fixed NullPointerException issues in bootBuildInfo and with @ConfigurationProperties beans. (Application startup)
• Corrected web environment handling in tests to respect WebApplicationType.REACTIVE. (Testing)
• Resolved issues with DataSource metrics not being auto-configured with lazy initialization. (Monitoring)

Before You Upgrade

• If using Elasticsearch, migrate from RestHighLevelClient to RestClientBuilder.
• Review and update any code relying on the deprecated DatabaseDriver.GAE.