A script that checks an http endpoint, parses json, and alerts when healthchecks fail

check-http-healthcheck.rb

#! /usr/bin/env ruby
#
# check-cc-heap-limit
#
# DESCRIPTION:
#   A script that checks an http endpoint, parses json, and alerts when healthchecks fail
#
# OUTPUT:
#   plain-text
#
# PLATFORMS:
#   Linux
#
# DEPENDENCIES:
#   gem: sensu-plugin
#   gem: httparty
#
# USAGE:
#
# NOTES:
#   
#
# LICENSE:
#   Copyright (c) 2017, Huy Nguyen <huyn@cloudcruise.com>

require 'sensu-plugin/check/cli'
require 'httparty'
require 'json'

class HealthCheck < Sensu::Plugin::Check::CLI
  option :host,
         short: '-h HOSTNAME',
         long: '--hostname HOSTNAME',
         description: 'Host to connect to query for healthcheck',
         default: 'localhost'

  option :port,
         short: '-p PORT',
         long: '--port PORT',
         description: 'Port to connect to query for healthcheck',
         default: '8081'

  option :timeout,
         short: '-t HTTP_TIMEOUT',
         long: '--timeout HTTP_TIMEOUT',
         description: 'HTTP timeout in case the HTTP request takes too long',
         default: 10,
         proc: proc(&:to_i)

  option :blacklist,
         short: '-b BLACKLIST',
         long: '--blacklist BLACKLIST',
         description: 'comma seperated list of checks that does not need to be alerted out if fails',
         default: nil,
         proc: proc(&:to_s)

  def run
    begin
      response = HTTParty.get("http://#{config[:host]}:#{config[:port]}/healthcheck", timeout: config[:timeout])
    rescue Errno::ECONNREFUSED => e
      critical "failed to connect to service healthcheck on #{config[:host]}:#{config[:port]}. #{e}"
    rescue Net::ReadTimeout => e
      warning "Timed out after #{config[:timeout]} seconds connecing to http://#{config[:port]}/healthcheck. #{e}"
    rescue StandardError => e
      unknown "Something went wrong accessing http://#{config[:host]}:#{config[:port]}/healthcheck. #{e}"
    end

    checks = JSON.parse(response.body)
    failed_checks = {}

    checks.keys.each do |key|
      unless !config[:blacklist].nil? && (config[:blacklist].include? key)
        next unless checks[key]['healthy'] == false
        failed_checks.store(key, checks[key]['message'])
      end
    end

    if failed_checks.any?
      critical "#{failed_checks} healthcheck(s) is/are failing on #{config[:host]}:#{config[:port]}"
    else
      ok "All healthchecks are passing for #{config[:host]}:#{config[:port]}"
    end
  end
end