problems with getting basic logging up with springboot and logback

Question

i have a simple spring boot app in groovy. here are the gradle dependencies i have set so far

dependencies {
    compile 'org.codehaus.groovy:groovy-all:2.3.11'
    compile 'org.easyrules:easyrules-core:2.2.1-SNAPSHOT'
    compile 'org.easyrules:easyrules-spring:2.2.1-SNAPSHOT'
    compile 'org.easyrules:easyrules-jmx:2.2.1-SNAPSHOT'
    testCompile group: 'junit', name: 'junit', version: '4.11'
    compile 'org.springframework.boot:spring-boot-starter'
    compile 'org.springframework.boot:spring-boot-starter-actuator'
    compile 'org.springframework.boot:spring-boot-starter-logging'
    compile 'ch.qos.logback:logback-classic:1.1.5'
}

this brings in slf4j-api, log4j-over-slf4j, jul-to-slf4j, and jcl-over-slf4f at versions 1.7.13

then in my helper class i have this

@Component
@PropertySource ("classpath:application.properties")
class RulesHelper {

    private static final Logger log = LoggerFactory.getLogger(RulesHelper.class)

followed by a bean def like this

@Bean
def rulesEngine () {
    assert jmxEnabled != null
    if ( !jmxEnabled ) {
        //return std rules engine
        println "returning std rules engine of type ${stdRulesEngine.getClass().name}"
        ruleEngine = stdRulesEngine
        return stdRulesEngine
    } else {
        println "returning jmx rules engine of type ${jmxRulesEngine.getClass().name}"
        //log.debug("hello from logger")
        //assert log

        ruleEngine = jmxRulesEngine
        return jmxRulesEngine  //JmxRulesExtends RulesEngine so should work
    }
}

if i uncomment out that assert i get an error when i run like this saying it cant find org.slf4j.event.LoggingEvent

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [java.lang.Object]: Factory method 'rulesEngine' threw exception; nested exception is java.lang.NoClassDefFoundError: org/slf4j/event/LoggingEvent
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588)
    ... 26 common frames omitted
Caused by: java.lang.NoClassDefFoundError: org/slf4j/event/LoggingEvent
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
    at java.lang.Class.getDeclaredMethods(Class.java:1975)
    at org.codehaus.groovy.reflection.CachedClass$3$1.run(CachedClass.java:85)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.codehaus.groovy.reflection.CachedClass$3.initValue(CachedClass.java:82)
    at org.codehaus.groovy.reflection.CachedClass$3.initValue(CachedClass.java:80)
    at org.codehaus.groovy.util.LazyReference.getLocked(LazyReference.java:46)
    at org.codehaus.groovy.util.LazyReference.get(LazyReference.java:33)
    at org.codehaus.groovy.reflection.CachedClass.getMethods(CachedClass.java:251)
    at groovy.lang.MetaClassImpl.populateMethods(MetaClassImpl.java:361)
    at groovy.lang.MetaClassImpl.fillMethodIndex(MetaClassImpl.java:340)
    at groovy.lang.MetaClassImpl.initialize(MetaClassImpl.java:3224)
    at org.codehaus.groovy.reflection.ClassInfo.getMetaClassUnderLock(ClassInfo.java:222)
    at org.codehaus.groovy.reflection.ClassInfo.getMetaClass(ClassInfo.java:253)
    at org.codehaus.groovy.reflection.ClassInfo.getMetaClass(ClassInfo.java:263)
    at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.getMetaClass(MetaClassRegistryImpl.java:259)
    at org.codehaus.groovy.runtime.InvokerHelper.getMetaClass(InvokerHelper.java:855)
    at org.codehaus.groovy.runtime.InvokerHelper.invokePojoMethod(InvokerHelper.java:888)
    at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod(InvokerHelper.java:880)
    at org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToBoolean(DefaultTypeTransformation.java:180)
    at org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.booleanUnbox(DefaultTypeTransformation.java:69)
    at org.softwood.easyrules.RulesHelper.rulesEngine(RulesHelper.groovy:79)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)
    ... 27 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.slf4j.event.LoggingEvent

what have i done wrong here - i thought this would work based on what i have read

Answer 1

well what do you know - dependency management issue - the latest springboot-starter-logging is only using slf4j-api.1.7.13,

however if you get the latest logback which i did logback_classic.1.1.5 there was breaking issue somewhere in the Api client librray that didnt export the class - which is why it couldnt be found. see logback issue/news

if you explicitly add the dependency

...
compile 'ch.qos.logback:logback-classic:1.1.5'
compile 'org.slf4j:slf4j-api:1.7.16'

to gradle.build, refresh and retry it all starts to work as nature expected. Blimey painful as usual as these things normally are

Answer 2

java.lang.NoClassDefFoundError: org/slf4j/event/LoggingEvent

Logback-classic version 1.1.4 and later require slf4j-api version 1.7.15 or later. With an earlier slf4j-api.jar in the classpath, attempting introspection of a Logger instance returned by logback version 1.1.4 or later will result in a NoClassDefFoundError similar to that shown below.

Exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/event/LoggingEvent
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2451)
    at java.lang.Class.privateGetPublicMethods(Class.java:2571)
    at java.lang.Class.getMethods(Class.java:1429)
    at java.beans.Introspector.getPublicDeclaredMethods(Introspector.java:1261)
    at java.beans.Introspector.getTargetMethodInfo(Introspector.java:1122)
    at java.beans.Introspector.getBeanInfo(Introspector.java:414)
    at java.beans.Introspector.getBeanInfo(Introspector.java:161)

Placing slf4j-api.jar version 1.7.15 or later in the classpath should solve the issue. Note that this problem only occurs with logback version 1.1.4 and later, other bindings such as slf4j-log4j, slf4j-jdk14 and slf4j-simple are unaffected.

Answer 3

corresponding maven dependency missing got it from https://mvnrepository.com/artifact/org.slf4j/slf4j-api/1.7.15

<dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.15</version>
        </dependency>