Spring Boot 4.1.0 Released: Official gRPC Support Boosts Java Microservices

Spring Boot 4.1.0 is the first feature‑enhancement release after 4.0. Each Spring Boot version has a one‑year lifecycle: 3.4.x and earlier are end‑of‑life, 3.5.x will soon be end‑of‑life, commercial support for the 3.x line ends at 3.3.x, and the open‑source line moves to 4.0+ (2.x ends at 2.7.x, 2.6.x and earlier are no longer maintained).

Official gRPC support

Spring Boot 4.1 bundles full gRPC support, eliminating the need for community starters. The bundled capabilities include:

gRPC Server

gRPC Client

gRPC Testing utilities

Auto‑configuration and dedicated configuration properties

Jackson configuration enhancements

Read and write features for all Jackson‑based formats (JSON, XML, CBOR) are now unified under:

spring.jackson.read.*
spring.jackson.write.*

A HandlerInstantiator is automatically registered so that Jackson components can obtain beans from the Spring container. Factory‑level customization is exposed via spring.jackson.factory.*. When property‑level configuration is insufficient, three builder‑level customizers can be used before the mapper is created:

JsonFactoryBuilderCustomizer

CborFactoryBuilderCustomizer

XmlFactoryBuilderCustomizer

HTTP client SSRF protection

The HTTP client now includes an InetAddressFilter that blocks Server‑Side Request Forgery (SSRF) attacks.

Observability enhancements

Building on the 4.0 observability foundation, 4.1 adds three automation layers:

Automatic context propagation (e.g., @Async methods automatically transmit trace context)

Automatic generation of observation rules

Extended OpenTelemetry capabilities

OpenTelemetry extensions include automatic rule activation for Kafka, RabbitMQ, and JVM metrics, plus new support for sampling, throttling, logging, SSL, and environment‑variable based configuration.

Log4j file‑rotation support

Four rotation strategies are now supported:

size (default) – rotates when a file reaches a configured size, e.g., 100 MB

time – rotates on a time schedule (daily, hourly, etc.)

size‑and‑time – rotates only when both size and time thresholds are met

cron – rotates according to a Cron expression

The size‑and‑time strategy is highlighted as the most practical for typical production systems because it limits file size while guaranteeing periodic archiving.