#!/usr/bin/env ruby

# Gathers nginx status stub statistics and submits them to Riemann.
# See http://wiki.nginx.org/HttpStubStatusModule for configuring Nginx appropriately

require File.expand_path('../../lib/riemann/tools', __FILE__)

class Riemann::Tools::NginxStatus
  include Riemann::Tools
  require 'net/http'
  require 'uri'

  opt :uri, "Nginx Stub Status URI", :default => 'http://localhost:8080/nginx_status'
  opt :checks, "Which metrics to report.", :type => :strings, :default => %w{active accepted handled requests reading writing waiting}
  opt :active_warning, "Active connections warning threshold", :default => 0
  opt :active_critical, "Active connections critical threshold", :default => 0
  opt :reading_warning, "Reading connections warning threshold", :default => 0
  opt :reading_critical, "Reading connections critical threshold", :default => 0
  opt :writing_warning, "Writing connections warning threshold", :default => 0
  opt :writing_critical, "Writing connections critical threshold", :default => 0
  opt :waiting_warning, "Waiting connections warning threshold", :default => 0
  opt :waiting_critical, "Waiting connections critical threshold", :default => 0

  def initialize
    @uri = URI.parse(opts[:uri])

    # sample response:
    #
    # Active connections: 1 
    # server accepts handled requests
    #  39 39 39 
    # Reading: 0 Writing: 1 Waiting: 0 
    @keys = %w{active accepted handled requests reading writing waiting}
    @re = /Active connections: (\d+) \n.+\n (\d+) (\d+) (\d+) \nReading: (\d+) Writing: (\d+) Waiting: (\d+)/m
  end

  def state(key, value)
    if opts.has_key? "#{key}_critical".to_sym
      critical_threshold = opts["#{key}_critical".to_sym]
      return 'critical' if critical_threshold > 0 and value >= critical_threshold
    end

    if opts.has_key? "#{key}_warning".to_sym
      warning_threshold = opts["#{key}_warning".to_sym]
      return 'warning' if warning_threshold > 0 and value >= warning_threshold
    end

    return 'ok'
  end

  def tick
    response = nil
    begin
      response = Net::HTTP.get(@uri)
    rescue => e
      report(
        :service => "nginx health",
        :state => "critical",
        :description => "Connection error: #{e.class} - #{e.message}"
      )
    end

    return if response.nil?

    report(
      :service => "nginx health",
      :state => "ok",
      :description => "Nginx status connection ok"
    )

    values = @re.match(response).to_a[1,7].map { |v| v.to_i }

    @keys.zip(values).each do |key, value|
      report({
        :service => "nginx #{key}",
        :metric  => value,
        :state   => state(key, value),
        :tags    => ['nginx']
      })
    end
  end
end

Riemann::Tools::NginxStatus.run