laradock/jenkins/init.groovy

import hudson.model.*;
import jenkins.model.*;


Thread.start {
      sleep 10000
      println "--> setting agent port for jnlp"
      def env = System.getenv()
      int port = env['JENKINS_SLAVE_AGENT_PORT'].toInteger()
      Jenkins.instance.setSlaveAgentPort(port)
      println "--> setting agent port for jnlp... done"
}