#!/usr/bin/env ruby
#
# Checks Redis INFO stats and limits values
# ===
#
# Copyright (c) 2012, Panagiotis Papadomitsos <pj@ezgr.net>
#
# Released under the same terms as Sensu (the MIT license); see LICENSE
# for details.

require 'sensu-plugin/check/cli'
require 'redis'

class RedisChecks < Sensu::Plugin::Check::CLI
  option :socket,
         short: '-s SOCKET',
         long: '--socket SOCKET',
         description: 'Redis socket to connect to (overrides Host and Port)',
         required: false

  option :host,
         short: '-h HOST',
         long: '--host HOST',
         description: 'Redis Host to connect to',
         required: false,
         default: '127.0.0.1'

  option :port,
         short: '-p PORT',
         long: '--port PORT',
         description: 'Redis Port to connect to',
         proc: proc(&:to_i),
         required: false,
         default: 6379

  option :password,
         short: '-P PASSWORD',
         long: '--password PASSWORD',
         description: 'Redis Password to connect with'

  option :warn_mem,
         short: '-w KB',
         long: '--warnmem KB',
         description: "Allocated KB of Redis memory on which we'll issue a WARNING",
         proc: proc(&:to_i),
         required: true

  option :crit_mem,
         short: '-c KB',
         long: '--critmem KB',
         description: "Allocated KB of Redis memory on which we'll issue a CRITICAL",
         proc: proc(&:to_i),
         required: true

  option :conn_failure_status,
         long: '--conn-failure-status EXIT_STATUS',
         description: 'Returns the following exit status for Redis connection failures',
         default: 'unknown',
         in: %w(unknown warning critical)

  option :timeout,
         short: '-t TIMEOUT',
         long: '--timeout TIMEOUT',
         description: 'Redis connection timeout',
         required: false,
         default: 5

  def run
    options = if config[:socket]
                { path: socket }
              else
                { host: config[:host], port: config[:port], timeout: config[:timeout] }
              end

    options[:password] = config[:password] if config[:password]
    redis = Redis.new(options)

    used_memory = redis.info.fetch('used_memory').to_i.div(1024)
    warn_memory = config[:warn_mem]
    crit_memory = config[:crit_mem]
    if used_memory >= crit_memory
      critical "Redis running on #{config[:host]}:#{config[:port]} is above the CRITICAL limit: #{used_memory}KB used / #{crit_memory}KB limit"
    elsif used_memory >= warn_memory
      warning "Redis running on #{config[:host]}:#{config[:port]} is above the WARNING limit: #{used_memory}KB used / #{warn_memory}KB limit"
    else
      ok "Redis memory usage: #{used_memory}KB is below defined limits"
    end
  rescue
    send(config[:conn_failure_status], "Could not connect to Redis server on #{config[:host]}:#{config[:port]}")
  end
end