zombie_killer.rb

#!/usr/bin/ruby

require 'rubygems'
require 'typhoeus'
require 'json'

jenkins = 'buildmaster.jenkins.com'
user    = "jenkins"
process = "ruby"
logfile = "/tmp/zombie_killer.log"

servers = {
  "buildslave01.jenkins.com" => "Alpha",
  "buildslave02.jenkins.com" => "Bravo",
  "buildslave03.jenkins.com" => "Charlie",
  "buildslave04.jenkins.com" => "Delta",
}

servers.each do |server, name|

  output = "[#{Time.new}] : #{server}"

  pid_results = `ssh -T -o StrictHostKeyChecking=no #{user}@#{server} "ps -C #{process} -o pid=" 2>/dev/null`

  if !pid_results.empty?

    res  = Typhoeus::Request.get("#{jenkins}/computer/#{name}/api/json?depth=2", :userpwd => "user:password")
    body = JSON.parse(res.body)

    executing = false

    executors = body["executors"]
    executors.each do |executor|
      executing = true if !executor["currentExecutable"].nil?
    end

    if !executing

      pids = pid_results.split("\n")

      pids.each do |pid|
        output += " : #{pid.strip} being killed"
        `ssh -tt -o StrictHostKeyChecking=no #{user}@#{server} "kill -9 #{pid.strip}" 2>/dev/null`
      end

    else
      output += " : cannot kill #{process} processes : executor #{name} is busy"
    end

  else
    output += " : No #{process} processes being executed"
  end

  output += "\n"
  File.open(logfile, 'a') {|f| f.write(output) }

end

File.open(logfile, 'a') {|f| f.write("\n") }