Gradle & SLF4J refusing to exclude transitive dependencies results in IllegalStateException

Question

I am getting this error when running unit tests on my project:

Caused by: java.lang.IllegalStateException: Detected both log4j-over-slf4j.jar AND bound slf4j-log4j12.jar on the class path, preempting StackOverflowError. See also http://www.slf4j.org/codes.html#log4jDelegationLoop for more details.
    at org.slf4j.impl.Log4jLoggerFactory.<clinit>(Log4jLoggerFactory.java:54)
    ... 29 more

I need SLF4J, but not the clash that the following dependencies is setting up:

dependencies {
    compile("org.springframework:spring-core:$springVersion")
    compile("org.springframework:spring-jdbc:$springVersion")
//    compile("org.springframework:spring-orm:$springVersion"
    compile("org.springframework:spring-tx:$springVersion")
    compile("org.springframework.data:spring-data-jpa:1.10.1.RELEASE") {
        exclude module: "slf4j-api"
        exclude module: "slf4j-over-slf4j"
        exclude module: "jcl-over-slf4j"
    }
    // tag::jetty[]
    compile("org.springframework.boot:spring-boot-starter-web:1.3.5.RELEASE") {
        exclude module: "spring-boot-starter-tomcat"
        exclude module: "slf4j-api"
        exclude module: "slf4j-over-slf4j"
        exclude module: "jcl-over-slf4j"
    }
    compile("org.springframework.boot:spring-boot-starter-jetty")
    // end::jetty[]
    // tag::actuator[]
    compile("org.springframework.boot:spring-boot-starter-actuator")
    // end::actuator[]
    testCompile("junit:junit")
    compile(group: 'org.hibernate.javax.persistence', name: 'hibernate-jpa-2.1-api', version: '1.0.0.Final')
    compile("org.apache.velocity:velocity:1.7")
    compile(group: 'org.slf4j', name: 'slf4j-api', version: '1.7.21')
    compile('org.slf4j:log4j-over-slf4j:1.7.21')
    compile(group: 'org.projectlombok', name: 'lombok', version: '1.16.8')
    testCompile("org.springframework.boot:spring-boot-starter-test")
    testCompile(group: 'junit', name: 'junit', version: '4.11')
}

I can stop the error via:

configurations {
  all*.exclude group: "org.slf4j"

}

but then I get ClassNotFoundExceptions at runtime because slf4j is needed (and its adapters).

Any ideas? I just want to exclude slf4j from Spring's dependencies. I have seen plenty of threads on this issue but not resolve it -- are my exclusions correct?

Answer 1

I just excluded spring-boot-starter-logging:

configurations {
    all*.exclude module: 'spring-boot-starter-logging'
}

My dependencies now look like this:

dependencies {
    compile "org.springframework:spring-core:$springVersion"
    compile "org.springframework:spring-jdbc:$springVersion"
    compile "org.springframework:spring-orm:$springVersion"
    compile "org.springframework:spring-tx:$springVersion"
    compile "org.springframework.data:spring-data-jpa:1.10.1.RELEASE"
    compile("org.springframework.boot:spring-boot-starter-web") {
        exclude module: "spring-boot-starter-tomcat"
    }
    compile("org.springframework.boot:spring-boot-starter-jetty")
    compile group: 'org.hibernate.javax.persistence', name: 'hibernate-jpa-2.1-api', version: '1.0.0.Final'
    compile "org.apache.velocity:velocity:1.7"
    compile group: 'org.slf4j', name: 'slf4j-api', version: '1.7.21'
    compile group: 'org.slf4j', name: 'slf4j-log4j12', version: '1.7.21'
    compile group: 'org.projectlombok', name: 'lombok', version: '1.16.8'
    testCompile("junit:junit")
    testCompile "org.springframework.boot:spring-boot-starter-test"
    testCompile group: 'junit', name: 'junit', version: '4.11'
}