Delete orphaned Jenkins workspaces

cleanup.groovy

import jenkins.slaves.WorkspaceLocator
workspaceRoot = WorkspaceLocator.all()[0].getWorkspaceRoot(Jenkins.get())

processDir(workspaceRoot, Jenkins.instance)

def processDir(rootDir, holder) {
  rootDir.list().each { dir ->
    deleteIfInvalid(dir, holder.getItem(dir.name))
  }
}

def deleteIfInvalid(dir, item) {
  if (!item) {
    println "Deleting [${dir}]"
    dir.deleteRecursive()
  } else if (item instanceof com.cloudbees.hudson.plugins.folder.Folder)  {
    processDir(dir, item)
  }
}