Observability module strongly depends on micrometer-tracing

[igbanam]

Hello maintainers,

Looks like there's an implicit requirement to always have Spring Observability setup when working with Spring Modulith. Should this be? Can this be relaxed?

I bumped into this when I added the Spring Modulith dependency, and added the Actuator Starter dependency, but did not add the dependencies required for observability yet. You can use this initializer to reproduce.

Steps?

• Download the initialized project
• run mvn spring-boot:run

Expectation

I expected this should just work™ i.e. start a Spring app waiting for connections.

The error I got was some inability to introspect into some micrometer class.

java.lang.IllegalStateException: Error processing condition on org.springframework.modulith.runtime.autoconfigure.SpringModulithRuntimeAutoConfiguration.modulithsApplicationRuntime
        at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:60) ~[spring-boot-autoconfigure-3.2.2.jar:3.2.2]
        at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:108) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForBeanMethod(ConfigurationClassBeanDefinitionReader.java:183) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:144) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:120) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:428) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:289) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:349) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:118) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:788) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:606) ~[spring-context-6.1.3.jar:6.1.3]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:146) ~[spring-boot-3.2.2.jar:3.2.2]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) ~[spring-boot-3.2.2.jar:3.2.2]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:456) ~[spring-boot-3.2.2.jar:3.2.2]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:334) ~[spring-boot-3.2.2.jar:3.2.2]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1354) ~[spring-boot-3.2.2.jar:3.2.2]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1343) ~[spring-boot-3.2.2.jar:3.2.2]
        at com.therubycentre.core.CoreApplication.main(CoreApplication.java:10) ~[classes/:na]
Caused by: java.lang.IllegalStateException: Failed to introspect Class [org.springframework.modulith.observability.autoconfigure.ModuleObservabilityAutoConfiguration] from ClassLoader [jdk.internal.loader.ClassLoaders$AppClassLoader@531d72ca]
        at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:483) ~[spring-core-6.1.3.jar:6.1.3]
        at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:360) ~[spring-core-6.1.3.jar:6.1.3]
        at org.springframework.util.ReflectionUtils.getUniqueDeclaredMethods(ReflectionUtils.java:417) ~[spring-core-6.1.3.jar:6.1.3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.lambda$getTypeForFactoryMethod$1(AbstractAutowireCapableBeanFactory.java:749) ~[spring-beans-6.1.3.jar:6.1.3]
        at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1740) ~[na:na]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryMethod(AbstractAutowireCapableBeanFactory.java:748) ~[spring-beans-6.1.3.jar:6.1.3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:681) ~[spring-beans-6.1.3.jar:6.1.3]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:652) ~[spring-beans-6.1.3.jar:6.1.3]
        at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1644) ~[spring-beans-6.1.3.jar:6.1.3]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:562) ~[spring-beans-6.1.3.jar:6.1.3]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:534) ~[spring-beans-6.1.3.jar:6.1.3]
        at org.springframework.boot.autoconfigure.condition.OnBeanCondition.collectBeanNamesForType(OnBeanCondition.java:247) ~[spring-boot-autoconfigure-3.2.2.jar:3.2.2]
        at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getBeanNamesForType(OnBeanCondition.java:240) ~[spring-boot-autoconfigure-3.2.2.jar:3.2.2]
        at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getBeanNamesForType(OnBeanCondition.java:230) ~[spring-boot-autoconfigure-3.2.2.jar:3.2.2]
        at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchingBeans(OnBeanCondition.java:183) ~[spring-boot-autoconfigure-3.2.2.jar:3.2.2]
        at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchOutcome(OnBeanCondition.java:158) ~[spring-boot-autoconfigure-3.2.2.jar:3.2.2]
        at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:47) ~[spring-boot-autoconfigure-3.2.2.jar:3.2.2]
        ... 17 common frames omitted
Caused by: java.lang.NoClassDefFoundError: io/micrometer/tracing/Tracer
        at java.base/java.lang.Class.getDeclaredMethods0(Native Method) ~[na:na]
        at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3402) ~[na:na]
        at java.base/java.lang.Class.getDeclaredMethods(Class.java:2504) ~[na:na]
        at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:465) ~[spring-core-6.1.3.jar:6.1.3]
        ... 33 common frames omitted
Caused by: java.lang.ClassNotFoundException: io.micrometer.tracing.Tracer
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641) ~[na:na]
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188) ~[na:na]
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520) ~[na:na]
        ... 37 common frames omitted

[igbanam]

If someone runs into this issue as well, adding the dependencies for Spring Observability from this article fixes it.

[odrotbohm]

There's no “using Spring Modulith” and no “the Spring Modulith dependency”. What's needed or not depends on which of the starters / Spring Modulith modules you use. Those are documented here.

As you have discovered (and this probably needs to be documented better or fixed) is that the observability module requires micrometer-tracing on the classpath.

[odrotbohm]

This should be fixed now. If you fancy giving the snapshots a try, altering the BOM version declared from a freshly created project to 1.2.0-SNAPSHOT should make the project start properly.