Fix Resilience4J class references

[gdupontf]

Describe the bug
Despite the release train aligning the latest versions with Spring Boot 4, some auto configurations reference the wrong Resilience4J classes, e.g. https://github.com/spring-cloud/spring-cloud-circuitbreaker/blob/main/spring-cloud-circuitbreaker-resilience4j%2Fsrc%2Fmain%2Fjava%2Forg%2Fspringframework%2Fcloud%2Fcircuitbreaker%2Fresilience4j%2FResilence4JMetricsOrderingAutoConfiguration.java#L33

I'd suggest a thorough check but this might be the only place. But it's enough to break our builds.

[gdupontf]

This should be the only other reference.

[gdupontf]

Given
#269
I understand we're in an awkward in-between then.

[ryanjbaxter]

And this is because you are not using resilience4j 2.3.x?

[gdupontf]

Indeed, even then with 2.4.0 it's either

• Use the Resilience4J springboot4 variant and lose some Spring Cloud features.
• Use the Resilience4J springboot3 variant and lose some Spring Boot features.

[ryanjbaxter]

Use the Resilience4J springboot3 variant and lose some Spring Boot features.

Yeah right now unfortunately there is not much we can do. We had to release Spring Boot 4 and Spring Cloud 2025.1.x before Resilience4J had any compatibility. All the Spring Cloud CircuitBreaker features work (as far as I know) with Spring Boot 4, Spring Cloud 2025.1.x and Resilience4j 2.3.x, but we can't make any guarantees about Resilience4j 2.4.x

[OathMeadow]

@ryanjbaxter

We are running Spring Boot 4 with Spring Cloud 2025.1.1 and everything seems to be fine, except for TimeLimiter metrics.
Before Spring Boot 4, the metrics were initialized by TimeLimiterMetricsAutoConfiguration. But after Spring Boot 4, this broke because Resilience4j reference Spring Boot 3 metric packages that no longer exists.

However, the Circuit Breaker metrics still works because now Spring Cloud circuit breaker initialize them instead, but Spring Cloud Circuit Breaker do not support TimeLimiter metrics. It is missing for some reason.

We did a workaround and made our own Resilience4j auto configuration of TimeLimiterMetricsAutoConfiguration.
Basically we do the exact same thing, but reference the correct packages. We will keep it until real support of Spring Boot 4 is released.

Thought you should now.

[ryanjbaxter]

However, the Circuit Breaker metrics still works because now Spring Cloud circuit breaker initialize them instead,

@OathMeadow do you mean this?

spring-cloud-circuitbreaker/spring-cloud-circuitbreaker-resilience4j/src/main/java/org/springframework/cloud/circuitbreaker/resilience4j/Resilience4JAutoConfiguration.java

Lines 129 to 180 in 605aa3b

	public static class MicrometerResilience4JCustomizerConfiguration {
	@Autowired(required = false)
	private @Nullable Resilience4JCircuitBreakerFactory factory;
	@Autowired(required = false)
	private @Nullable Resilience4jBulkheadProvider bulkheadProvider;
	@Autowired(required = false)
	private @Nullable TaggedCircuitBreakerMetrics taggedCircuitBreakerMetrics;
	@Autowired
	private MeterRegistry meterRegistry;
	@PostConstruct
	public void init() {
	if (factory != null) {
	if (taggedCircuitBreakerMetrics == null) {
	taggedCircuitBreakerMetrics = TaggedCircuitBreakerMetrics
	.ofCircuitBreakerRegistry(factory.getCircuitBreakerRegistry());
	}
	taggedCircuitBreakerMetrics.bindTo(meterRegistry);
	}
	if (bulkheadProvider != null) {
	TaggedBulkheadMetrics.ofBulkheadRegistry(bulkheadProvider.getBulkheadRegistry()).bindTo(meterRegistry);
	TaggedThreadPoolBulkheadMetrics
	.ofThreadPoolBulkheadRegistry(bulkheadProvider.getThreadPoolBulkheadRegistry())
	.bindTo(meterRegistry);
	}
	}
	}
	@Configuration(proxyBeanMethods = false)
	@ConditionalOnBean(ObservationRegistry.class)
	@ConditionalOnProperty(value = "spring.cloud.circuitbreaker.resilience4j.micrometer.enabled", matchIfMissing = true)
	public static class ObservationRegistryCustomizerResilience4jCustomizer {
	@Autowired
	ObservationRegistry observationRegistry;
	@Autowired(required = false)
	private @Nullable Resilience4JCircuitBreakerFactory factory;
	@PostConstruct
	public void init() {
	if (this.factory != null) {
	this.factory.setObservationRegistry(this.observationRegistry);
	}
	}
	}

Would you mind sharing your custom auto configuration for the TimeLimiter?

[OathMeadow]

@ryanjbaxter

Here is the example overridden auto-configuration that we use:

/**
 * Temporary Spring Boot 4 override for
 * {@link io.github.resilience4j.springboot3.timelimiter.autoconfigure.TimeLimiterMetricsAutoConfiguration}.
 * <p>
 * Resilience4j 2.3.0 still targets Spring Boot 3 actuator auto-configuration class names.
 * This replacement keeps time-limiter metric registration working in Boot 4 by updating
 * the {@code @AutoConfigureAfter} references while preserving the original conditions and beans.
 * Remove this class and the imports in META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports
 * after upgrading to a Resilience4j release with native Spring Boot 4 support.
 */
@Configuration
@ConditionalOnClass({MeterRegistry.class, TimeLimiter.class, TaggedTimeLimiterMetricsPublisher.class})
@ConditionalOnMissingClass(
        "io.github.resilience4j.springboot.timelimiter.autoconfigure.TimeLimiterMetricsAutoConfiguration"
)
@AutoConfigureAfter(name = { "org.springframework.boot.micrometer.metrics.autoconfigure.MetricsAutoConfiguration",
        "org.springframework.boot.micrometer.metrics.autoconfigure.export.simple.SimpleMetricsExportAutoConfiguration" })
@ConditionalOnProperty(value = "resilience4j.timelimiter.metrics.enabled", matchIfMissing = true)
public class TimeLimiterMetricsOverriddenAutoConfiguration {

    @Bean
    @ConditionalOnProperty(value = "resilience4j.timelimiter.metrics.legacy.enabled", havingValue = "true")
    @ConditionalOnMissingBean
    public TaggedTimeLimiterMetrics registerTimeLimiterMetrics(TimeLimiterRegistry timeLimiterRegistry) {
        return TaggedTimeLimiterMetrics.ofTimeLimiterRegistry(timeLimiterRegistry);
    }

    @Bean
    @ConditionalOnBean(MeterRegistry.class)
    @ConditionalOnProperty(value = "resilience4j.timelimiter.metrics.legacy.enabled", havingValue = "false", matchIfMissing = true)
    @ConditionalOnMissingBean
    public TaggedTimeLimiterMetricsPublisher taggedTimeLimiterMetricsPublisher(MeterRegistry meterRegistry) {
        return new TaggedTimeLimiterMetricsPublisher(meterRegistry);
    }
}

Basically it is identical to TimeLimiterMetricsAutoConfiguration from Resilience4j, but with some differences.
Below is Resilience4j class from their io.github.resilience4j.springboot3.timelimiter.autoconfigure package:

@Configuration
@ConditionalOnClass({MeterRegistry.class, TimeLimiter.class, TaggedTimeLimiterMetricsPublisher.class})
@AutoConfigureAfter(name = { "org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration",
	"org.springframework.boot.actuate.autoconfigure.metrics.export.simple.SimpleMetricsExportAutoConfiguration" })
@ConditionalOnProperty(value = "resilience4j.timelimiter.metrics.enabled", matchIfMissing = true)
public class TimeLimiterMetricsAutoConfiguration {

    @Bean
    @ConditionalOnProperty(value = "resilience4j.timelimiter.metrics.legacy.enabled", havingValue = "true")
    @ConditionalOnMissingBean
    public TaggedTimeLimiterMetrics registerTimeLimiterMetrics(TimeLimiterRegistry timeLimiterRegistry) {
        return TaggedTimeLimiterMetrics.ofTimeLimiterRegistry(timeLimiterRegistry);
    }

    @Bean
    @ConditionalOnBean(MeterRegistry.class)
    @ConditionalOnProperty(value = "resilience4j.timelimiter.metrics.legacy.enabled", havingValue = "false", matchIfMissing = true)
    @ConditionalOnMissingBean
    public TaggedTimeLimiterMetricsPublisher taggedTimeLimiterMetricsPublisher(MeterRegistry meterRegistry) {
        return new TaggedTimeLimiterMetricsPublisher(meterRegistry);
    }

}

Notice that their @AutoConfigureAfter defines Spring Boot 3 metric classes.

"org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration"
"org.springframework.boot.actuate.autoconfigure.metrics.export.simple.SimpleMetricsExportAutoConfiguration" 

These classes has moved in Spring Boot 4 to:

"org.springframework.boot.micrometer.metrics.autoconfigure.MetricsAutoConfiguration"
"org.springframework.boot.micrometer.metrics.autoconfigure.export.simple.SimpleMetricsExportAutoConfiguration"

This means that it references classes that do not exist in Spring Boot 4. And therefore it will NEVER be auto configured, if you run Spring Boot 4. The same problem also applies for CircuitBreakerMetricsAutoConfiguration and ThreadPoolBulkheadMetricsAutoConfiguration etc.

So if this happens, I noticed that metric auto configuration from Spring Cloud Circuit Breaker is triggered instead, in Resilience4JAutoConfiguration::MicrometerResilience4JCustomizerConfiguration, because this auto configuration defines:

@ConditionalOnMissingBean({ TaggedCircuitBreakerMetricsPublisher.class }) which in this case is now true.

However, the Resilience4JAutoConfiguration::MicrometerResilience4JCustomizerConfiguration do not support TimeLimiter metrics.

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnBean({ MeterRegistry.class })
	@ConditionalOnClass(name = { "io.github.resilience4j.micrometer.tagged.TaggedCircuitBreakerMetrics",
			"io.github.resilience4j.micrometer.tagged.TaggedCircuitBreakerMetricsPublisher" })
	@ConditionalOnMissingBean({ TaggedCircuitBreakerMetricsPublisher.class })
	public static class MicrometerResilience4JCustomizerConfiguration {

		@Autowired(required = false)
		private @Nullable Resilience4JCircuitBreakerFactory factory;

		@Autowired(required = false)
		private @Nullable Resilience4jBulkheadProvider bulkheadProvider;

		@Autowired(required = false)
		private @Nullable TaggedCircuitBreakerMetrics taggedCircuitBreakerMetrics;

		@Autowired
		private MeterRegistry meterRegistry;

		@PostConstruct
		public void init() {
			if (factory != null) {
				if (taggedCircuitBreakerMetrics == null) {
					taggedCircuitBreakerMetrics = TaggedCircuitBreakerMetrics
						.ofCircuitBreakerRegistry(factory.getCircuitBreakerRegistry());
				}
				taggedCircuitBreakerMetrics.bindTo(meterRegistry);
			}
			if (bulkheadProvider != null) {
				TaggedBulkheadMetrics.ofBulkheadRegistry(bulkheadProvider.getBulkheadRegistry()).bindTo(meterRegistry);
				TaggedThreadPoolBulkheadMetrics
					.ofThreadPoolBulkheadRegistry(bulkheadProvider.getThreadPoolBulkheadRegistry())
					.bindTo(meterRegistry);
			}
			if (bulkheadProvider != null) {
				TaggedBulkheadMetrics.ofBulkheadRegistry(bulkheadProvider.getBulkheadRegistry()).bindTo(meterRegistry);
				TaggedThreadPoolBulkheadMetrics
					.ofThreadPoolBulkheadRegistry(bulkheadProvider.getThreadPoolBulkheadRegistry())
					.bindTo(meterRegistry);
			}
		}

	}

This are my findings.