Unable to use logback.groovy, but logback.xml works - gradle

Question

I wanted to configure Logback using Groovy DSL. The file is very simple:
import ch.qos.logback.classic.encoder.PatternLayoutEncoder
import ch.qos.logback.core.ConsoleAppender
import static ch.qos.logback.classic.Level.DEBUG
import static ch.qos.logback.classic.Level.INFO
appender("stdout", ConsoleAppender) {
encoder(PatternLayoutEncoder) {
pattern = "%d %p [%c] - <%m>%n"
}
}
root(INFO, ["stdout"])
I use Gradle to build my application and run it with jettyRun. I get the following error:
Failed to instantiate [ch.qos.logback.classic.LoggerContext]
Reported exception:
org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'ch.qos.logback.core.ConsoleAppender[null]' with class 'ch.qos.logback.core.ConsoleAppender' to class 'ch.qos.logback.core.Appender'
at org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToType(DefaultTypeTransformation.java:360)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.castToType(ScriptBytecodeAdapter.java:599)
at ch.qos.logback.classic.gaffer.ConfigurationDelegate.appender(ConfigurationDelegate.groovy:119)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at org.codehaus.groovy.runtime.metaclass.MixinInstanceMetaMethod.invoke(MixinInstanceMetaMethod.java:53)
at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoMetaMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:308)
at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:52)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:46)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:149)
However, when I switch to equivalent XML configuration, everything works. What am I doing wrong?
Using Logback 1.0.0. Tried with Logback 1.0.3.

Answer 1

I figured the solution out, but some questions remain opened. The problem was that I had no proper Groovy on the classpath. I decided to make an example project to demonstrate this bug. I started with a console application using Gradle's "application" plugin. I didn't include Groovy as dependency.
apply plugin: 'application'
repositories {
mavenCentral()
}
ext.logbackVersion = '1.0.3'
ext.slf4jVersion = '1.6.4'
dependencies {
compile "ch.qos.logback:logback-classic:$ext.logbackVersion"
compile "org.slf4j:jcl-over-slf4j:$ext.slf4jVersion"
//runtime "org.codehaus.groovy:groovy:1.8.6" // the problem was here
}
mainClassName = "org.test.Main"
This gave me an error, which is quite straighforward.
|-ERROR in ch.qos.logback.classic.LoggerContext[default] - Groovy classes are not available on the class path. ABORTING INITIALIZATION.
OK, cool. The dependency was missing - easy to fix. But why didn't I get the same error when I ran my web application? Adding Groovy dependency solved the initial problem in the web application. I stripped my project down and will create a corresponding JIRA. Perhaps, Groovy on classpath detection is not quite correct.

Answer 2

The GroovyCastException "cannot cast ConsoleAppender as Appender" has all the bearings of a class loader issue. Which version of groovy is this? Could you open a bug report including a test case for reproducing this issuew?

Answer 3

colleagues.
I have faced almost the same trouble today:
When I use logback.xml everything works fine
When I use logback.groovy in IntelliJ IDEA eveything works fine too
When I use logback.groovy when start my script from command line I got a lot of errors like
:
D:\Projects\PRDMonitoring\sources>groovy tray.groovy PRD
Failed to instantiate [ch.qos.logback.classic.LoggerContext]
Reported exception:
org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Script1.groovy: 2: unable to resolve class ch.qos.logback.classic.filter.LevelFilter
# line 2, column 1.
import ch.qos.logback.classic.filter.LevelFilter
^
Script1.groovy: -1: unable to resolve class ch.qos.logback.classic.encoder.PatternLayoutEncoder
# line -1, column -1.
Script1.groovy: 3: unable to resolve class ch.qos.logback.core.ConsoleAppender
# line 3, column 1.
import ch.qos.logback.core.ConsoleAppender
^
Script1.groovy: -1: unable to resolve class ch.qos.logback.classic.Level
# line -1, column -1.
Script1.groovy: 6: unable to resolve class ch.qos.logback.core.spi.FilterReply
# line 6, column 1.
import static ch.qos.logback.core.spi.FilterReply.ACCEPT
^
Script1.groovy: 7: unable to resolve class ch.qos.logback.core.spi.FilterReply
# line 7, column 1.
import static ch.qos.logback.core.spi.FilterReply.DENY
But after a couple of minutes to find a solution I figured out, that the following string before #Grapes annotation fixes a trouble with classes loading #GrabConfig(systemClassLoader=true)
#GrabConfig(systemClassLoader=true)
#Grapes([
#Grab(group = 'org.codehaus.groovy.modules.http-builder', module = 'http-builder', version = '0.6'),
#Grab(group = 'org.apache.commons', module='commons-lang3', version='3.0'),
#Grab(group = 'commons-io', module = 'commons-io', version = '2.4'),
#Grab(group = 'joda-time', module = 'joda-time', version = '2.9.4'),
#Grab(group = 'ch.qos.logback', module = 'logback-classic', version = '1.1.7'),
#Grab(group = 'ch.qos.logback', module = 'logback-core', version = '1.1.7')
])