Jenkins tool to remove old builds from queues so that only the latest commit gets run

jenkins_queue_optimizer.rb

require 'rubygems'
require 'httparty'
require 'nokogiri'

# This tool removes old builds from queues so that only the latest commit gets run.
# This way slow jobs won't fall behind, they will just skip commits upto the latest
# available commit that was successful in upstream projects.
class JenkinsQueueOptimizer
  class Api
    include HTTParty
    base_uri "http://localhost:8080"
  end

  def self.run
    loop do
      begin
        projects_with_more_than_one_item_in_queue.each do |project|
          old_item_ids_for_project(project).each do |item_id|
            puts "Clearing out old queue item #{item_id} for #{project}."
            cancel_queue_item(item_id)
          end
        end
      rescue Exception => ex
        puts 'Error:'
        puts ex.message
        puts ex.backtrace
      end

      sleep 5
    end
  end

  def self.projects_with_more_than_one_item_in_queue
    puts "Checking for old items in build queues..."
    data = Api.get("/queue/api/json", :format => :json).to_hash

    projects = {}
    data["items"].each do |item|
      project = item["task"]["name"]
      projects[project] ||= 0
      projects[project] += 1
    end

    projects.find_all { |project, queue_size| queue_size > 1 }.map { |project, _| project }
  end

  def self.old_item_ids_for_project(project)
    page = Api.get("/job/#{project}").body
    doc = Nokogiri::HTML(page)

    queue_item_ids = []
    doc.css("td > div > a").each do |link|
      link = link.attributes["href"].value
      if link =~ /queue\/item\/(.+?)\//
        queue_item_ids << $1.to_i
      end
    end

    queue_item_ids.sort[0...-1]
  end

  def self.cancel_queue_item(item_id)
    Api.get("/queue/item/#{item_id}/cancelQueue")
  end
end

JenkinsQueueOptimizer.run

jenkins_queue_optimizer_daemon

#!/usr/bin/env ruby
require 'rubygems'
require 'daemons'
Daemons.run(File.expand_path(File.join(File.dirname(__FILE__), "jenkins_queue_optimizer.rb")))