Jenkins/Hudson CLI API to modify the node labels using Groovy

Question

Does anyone know how to modify the Jenkins/Hudson node labels in a non-manually way? I mean, thorough an API like the CLI API that this tool offers (without restarting Jenkins/H

Answer 1

Note: the other answers are a bit old, so it could be that the API has appeared since then.

Node labels are accessed in the API as a single string, just like in the Configure screen.

To read and write labels: Node.getLabelString() and Node.setLabelString(String).

Note that you can get the effective labels as well via: Node.getAssignedLabels(), which returns a Collection of LabelAtom that includes dynamically computed labels such as the 'self-label' (representing the node name itself).

Last, these methods on the Node class are directly accessible from the slave objects also, e.g. as a System Groovy Script:

hudson = hudson.model.Hudson.instance
hudson.slaves.findAll { it.nodeName.equals("slave4") }.each { slave -> 
  print "Slave  $slave.nodeName : Labels: $slave.labelString"
  slave.labelString = slave.labelString + " " + "offline"
  println "   --> New labels: $slave.labelString"
}
hudson.save()