openvpn-metrics.rb

#!/usr/bin/env ruby

# Get OpenVPN stats
#
# Requires the admin interface to be enabled on the OpenVPN server.
# Opens a telnet connection to the admin interface, collects data,
# and sends it back to Sensu.
#
# Some command-line options (either the builtin defaults
# or the options sent by sensu-server) can be overriden locally
# by a .json config file, like this:
#
# $ cat /etc/sensu/conf.d/openvpn-metrics.json
# {
#   "openvpn-metrics": {
#     "host": "1.2.3.4",
#     "port": "12345",
#     "service": "users"
#   }
# }
#
# This is to allow different VPN servers to bind the admin interface to
# different host:port combos, while still sending the same command to
# all sensu-client instances.
#
# In other words, for --host and --port the order of importance, starting
# with the most important, is:
#
# 1. Values defined locally in sensu/conf.d/*.json
# 2. Command line options passed via --host and --port
# 3. Built-in defaults (displayed with --help)

require 'rubygems' if RUBY_VERSION < '1.9.0'
require 'sensu-plugin/metric/cli'
require 'sensu-plugin/utils'
require 'net/telnet'

class OpenvpnGraphite < Sensu::Plugin::Metric::CLI::Graphite

  include Sensu::Plugin::Utils

  option :scheme,
    :description => "Metric naming scheme, text to prepend to metric",
    :short => "-s SCHEME",
    :long => "--scheme SCHEME",
    :default => "#{Socket.gethostname}.openvpn"

  option :host,
    :description => "Host to connect to",
    :short => "-h HOST",
    :long => "--host HOST",
    :default => "localhost"

  option :port,
    :description => "Port to connect to",
    :short => "-p PORT",
    :long => "--port PORT",
    :default => 1195

  option :timeout,
    :description => "Connection timeout",
    :short => "-t TIMEOUT",
    :long => "--timeout TIMEOUT",
    :default => 10

  option :prompt,
    :description => "Initial prompt for OpenVPN admin interface",
    :short => "-r PROMPT",
    :long => "--prompt PROMPT",
    :default => ">INFO:OpenVPN Management Interface Version 1 -- type 'help' for more info\n"

  option :service,
    :description => "If more than one openvpn service is running here, name this one to identify it",
    :short => "-e SERVICE",
    :long => "--service SERVICE",
    :default => "main"

  def run

    # Are these options overriden locally in .json?
    if defined? settings['openvpn-metrics']['host']
      def_host = settings['openvpn-metrics']['host']
    else
      def_host = config[:host]
    end

    if defined? settings['openvpn-metrics']['port']
      def_port = settings['openvpn-metrics']['port']
    else
      def_port = config[:port]
    end

    if defined? settings['openvpn-metrics']['service']
      def_service = settings['openvpn-metrics']['service']
    else
      def_service = config[:service]
    end

    # collect data
    # telnet into admin interface
    vpn = Net::Telnet.new("Host" => def_host,
                           "Port" => def_port,
                           "Timeout" => config[:timeout],
                           "Telnetmode" => false,
                           "Prompt" => config[:prompt])

    # issue stats command
    status = vpn.cmd("String" => "load-stats",
                     "Match" => /^SUCCESS: nclients=[0-9]+,bytesin=[0-9]+,bytesout=[0-9]+/).lines[1].chomp

    vpn.close

    # Example output from actual telnet session:
    #
    # >INFO:OpenVPN Management Interface Version 1 -- type 'help' for more info
    # load-stats
    # SUCCESS: nclients=1,bytesin=371632,bytesout=176455

    # grok output
    stat_fields = status.split(',')
    nclients = stat_fields[0].split('=')[1]
    bytesin = stat_fields[1].split('=')[1]
    bytesout = stat_fields[2].split('=')[1]

    # send metrics to Sensu
    output "#{config[:scheme]}.#{def_service}.nclients", nclients
    output "#{config[:scheme]}.#{def_service}.bytesin", bytesin
    output "#{config[:scheme]}.#{def_service}.bytesout", bytesout

    ok
  end

end