#! /usr/bin/env ruby
#
#   metric-postgres-statstable
#
# DESCRIPTION:
#
#   This plugin collects postgres database metrics from the pg_stat tables
#
# OUTPUT:
#   metric data
#
# PLATFORMS:
#   Linux
#
# DEPENDENCIES:
#   gem: sensu-plugin
#   gem: pg
#
# USAGE:
#   ./metric-postgres-statstable.rb -u db_user -p db_pass -h db_host -d db -s scope
#
# NOTES:
#   Requires PSQL `track_counts` enabled
#
# LICENSE:
#   Copyright (c) 2012 Kwarter, Inc <platforms@kwarter.com>
#   Author Gilles Devaux <gilles.devaux@gmail.com>
#   Released under the same terms as Sensu (the MIT license); see LICENSE
#   for details.
#

require 'sensu-plugin/metric/cli'
require 'pg'
require 'socket'

class PostgresStatsTableMetrics < Sensu::Plugin::Metric::CLI::Graphite
  option :user,
         description: 'Postgres User',
         short: '-u USER',
         long: '--user USER'

  option :password,
         description: 'Postgres Password',
         short: '-p PASS',
         long: '--password PASS'

  option :hostname,
         description: 'Hostname to login to',
         short: '-h HOST',
         long: '--hostname HOST',
         default: 'localhost'

  option :port,
         description: 'Database port',
         short: '-P PORT',
         long: '--port PORT',
         default: 5432

  option :database,
         description: 'Database name',
         short: '-d DB',
         long: '--db DB',
         default: 'postgres'

  option :scope,
         description: 'Scope, see http://www.postgresql.org/docs/9.2/static/monitoring-stats.html',
         short: '-s SCOPE',
         long: '--scope SCOPE',
         default: 'user'

  option :scheme,
         description: 'Metric naming scheme, text to prepend to $queue_name.$metric',
         long: '--scheme SCHEME',
         default: "#{Socket.gethostname}.postgresql"

  option :timeout,
         description: 'Connection timeout (seconds)',
         short: '-T TIMEOUT',
         long: '--timeout TIMEOUT',
         default: nil

  def run
    timestamp = Time.now.to_i

    con     = PG.connect(host: config[:hostname],
                         dbname: config[:database],
                         user: config[:user],
                         password: config[:password],
                         port: config[:port],
                         connect_timeout: config[:timeout])
    request = [
      'select sum(seq_scan) as seq_scan, sum(seq_tup_read) as seq_tup_read,',
      'sum(idx_scan) as idx_scan, sum(idx_tup_fetch) as idx_tup_fetch,',
      'sum(n_tup_ins) as n_tup_ins, sum(n_tup_upd) as n_tup_upd, sum(n_tup_del) as n_tup_del,',
      'sum(n_tup_hot_upd) as n_tup_hot_upd, sum(n_live_tup) as n_live_tup, sum(n_dead_tup) as n_dead_tup',
      "from pg_stat_#{config[:scope]}_tables"
    ]
    con.exec(request.join(' ')) do |result|
      result.each do |row|
        output "#{config[:scheme]}.statstable.#{config[:database]}.seq_scan", row['seq_scan'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.seq_tup_read", row['seq_tup_read'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.idx_scan", row['idx_scan'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.idx_tup_fetch", row['idx_tup_fetch'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.n_tup_ins", row['n_tup_ins'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.n_tup_upd", row['n_tup_upd'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.n_tup_del", row['n_tup_del'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.n_tup_hot_upd", row['n_tup_hot_upd'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.n_live_tup", row['n_live_tup'], timestamp
        output "#{config[:scheme]}.statstable.#{config[:database]}.n_dead_tup", row['n_dead_tup'], timestamp
      end
    end

    ok
  end
end