Purge Varnish Cache module

module Varnish 
  require 'net/telnet' 
  
  #requires telnet access from deploy machine
  def global_purge(varnish_host,varnish_port)
  #It WILL timeout, just accept it. Varnish does not have a command prompt.       
    result = run_varnish_cmd(varnish_host,varnish_port,'url.purge .*',3)
    if result.include?("200")
      return [true,"Varnish purged OK."]
    else
      return [false,"Varnish not purged."]
    end   
  end
  
  
  def reload_vcl(varnish_host,varnish_port,config)
    
    result = []
    current_config = "deployed_#{Time.now.to_i}"
    #newly loaded configs will look like this in vcl.list:
    # 1 deployed_1257272386
    result << run_varnish_cmd(varnish_host,varnish_port,"vcl.load #{current_config} #{config}",3)
    result << run_varnish_cmd(varnish_host,varnish_port,"vcl.use #{current_config}",3)
      @vcl_ok = false
      result.each{|ea| @vcl_ok = true if (ea && ea.include?("VCL compiled"))}
      if @vcl_ok
        return [true,"Varnish config reloaded."]
      else
        return [false,"Varnish config NOT reloaded! Result: \n#{result}"]
      end
  end  
  
  def discard_unused_configs(varnish_host,varnish_port)
    list_s = run_varnish_cmd(varnish_host,varnish_port,"vcl.list",3)
    @to_delete = []
    configs = list_s.split("\n")
    configs.each{|ea| @to_delete << ea.gsub('available       0 ','') if (ea && ea.include?('available'))}
    @to_delete.each{|conf| run_varnish_cmd(varnish_host,varnish_port,"vcl.discard #{conf}",3)}
    if @to_delete.size > 0 
      return [true,"Varnish configs discarded: #{@to_delete.join("|")}"]
    else
      return [false,"Varnish configs discard attempt failed: #{@to_delete}"]
    end
  end
  
  private
  # run_varnish_cmd('127.1.1.1','6082','vcl.list',2)
  def run_varnish_cmd(host,port,cmd,timeout=5)
     @res = nil
     begin
        telnet_host = Net::Telnet::new("Host" => host,
        "Port" => port.to_i,
        "Timeout" => timeout)
        telnet_host.cmd(cmd) { |c| @res = c}
        #It WILL timeout, just accept it. Varnish does not have a command prompt that Ruby Telnet can expect     
      rescue Exception 
          return @res
      end
      return nil
  end

end