How to mix ResolutionStrategies with Gradle

Question

Let's say I have the following in my gradle build script:

configurations.all {
  resolutionStrategy {

    failOnVersionConflict()

    force 'com.google.guava:guava:18.0'
    }
}

This will fail if more than one version of a jar is found, except for guava where it will force to version 18.0.

Now let's imagine that I want to have failOnVersionConflict() for all external jars, and be forced to use the force clause (so I know what I'm doing), but I want to use the default resolutionStrategy (newest version) for some specific group, like com.mycompany.

Is such a thing possible?

I was looking at this documentation page:

https://gradle.org/docs/current/dsl/org.gradle.api.artifacts.ResolutionStrategy.html

Answer 1

I found my own answer... But it involves a bit of "hacking"... But, after all, that's just what gradle offers...

def dependencyErrors = 0

configurations.all {
  resolutionStrategy {

    def thirdPartyPackages = [:]
    def forced = [ 
        'com.google.guava:guava' : '18.0'
        //Here all forced dependencies...
    ]


     eachDependency { DependencyResolveDetails details ->


          if (!details.requested.group.startsWith('com.mycompany')) {

                def key = details.requested.group + ":" + details.requested.name
                if(!thirdPartyPackages.containsKey(key)) {
                    if(forced.containsKey(key)) {
                        details.useVersion forced.get(key)
                    }                   
                    else {
                        thirdPartyPackages.put(key, details.requested.version);
                    }
                }
                else {
                    def existing =  thirdPartyPackages.get(key);
                    if(existing != details.requested.version) {
                        logger.error "Conflicting versions for [$key]"
                        logger.error "    [$existing]"
                        logger.error "    [$details.requested.version]"
                        dependencyErrors++
                    }
                }
          }
      }

  }
}

myTask.doFirst {
  //here it might also be doLast, or whatever you need. I just put it before a war task, but it might depend on each need. 
  if(dependencyErrors > 0) {
    ant.fail 'There are ' + dependencyErrors + ' conflicting jar versions in the build.'
  }
}