Gradle: Force Custom Task to always run (no cache) - groovy

Question

I wrote up a custom Gradle task to handle some dependency resolution on the file system where the paths are configurable. I want tasks of this type to always run. It seems though they only run once, I'm guessing because the inputs never seem to change.
I am aware of using configurations { resolutionStrategy.cacheChangingModulesFor 0, 'seconds' } to effectively disable the cache, but I only want it to apply to very specific tasks. Also am aware of --rerun-tasks command line prompt, which is also similar. Neither feel like the best solution, there must be a way to set this up properly in the custom task definition.
Follows is my current implementation. I also had a version prior where the first 3 def String statements were instead #Input annotated String declarations.
class ResolveProjectArchiveDependency extends DefaultTask {
def String archiveFilename = ""
def String relativeArchivePath = ""
def String dependencyScope = ""
#OutputFile
File outputFile
#TaskAction
void resolveArtifact() {
def arcFile = project.file("dependencies/"+dependencyScope+"/"+archiveFilename)
def newArcFile = ""
if(project.hasProperty('environmentSeparated') && project.hasProperty('separatedDependencyRoot')){
println "Properties set denoting the prerelease environment is separated"
newArcFile = project.file(project.ext.separatedDependencyRoot+relativeArchivePath+archiveFilename)
} else {
newArcFile = project.file('../../'+relativeArchivePath+archiveFilename)
}
if(!newArcFile.isFile()){
println "Warn: Could not find the latest copy of " + archiveFilename + ".."
if(!arcFile.isFile()) {
println "Error: No version of " + archiveFilename + " can be found"
throw new StopExecutionException(archiveFilename +" missing")
}
}
if(!arcFile.isFile()) {
println archiveFilename + " jar not in dependencies, pulling from archives"
} else {
println archiveFilename + " jar in dependencies. Checking for staleness"
def oldHash = generateMD5(new File(arcFile.path))
def newHash = generateMD5(new File(newArcFile.path))
if(newHash.equals(oldHash)) {
println "Hashes for the jars match. Not pulling in a copy"
return
}
}
//Copy the archive
project.copy {
println "Copying " + archiveFilename
from newArcFile
into "dependencies/"+dependencyScope
}
}
def generateMD5(final file) {
MessageDigest digest = MessageDigest.getInstance("MD5")
file.withInputStream(){is->
byte[] buffer = new byte[8192]
int read = 0
while( (read = is.read(buffer)) > 0) {
digest.update(buffer, 0, read);
}
}
byte[] md5sum = digest.digest()
BigInteger bigInt = new BigInteger(1, md5sum)
return bigInt.toString(16)
}
}
Here's an example of usage of the task:
task handleManagementArchive (type: com.moremagic.ResolveProjectArchiveDependency) {
archiveFilename = 'management.jar'
relativeArchivePath = 'management/dist/'
dependencyScope = 'compile/archive'
outputFile = file('dependencies/'+dependencyScope+'/'+archiveFilename)
}

Answer 1

You can achieve this by setting outputs.upToDateWhen { false } on the task.
This can be performed in your build.gradle file:
handleManagementArchive.outputs.upToDateWhen { false }
It can also be done in the constructor of your custom task.
ResolveProjectArchiveDependency() {
outputs.upToDateWhen { false }
}