sensu-plugins/sensu-plugins-aws

#! /usr/bin/env ruby
#
# check-elb-health
#
# DESCRIPTION:
#   This plugin checks the health of an Amazon Elastic Load Balancer.
#
# OUTPUT:
#   plain-text
#
# PLATFORMS:
#   Linux
#
# DEPENDENCIES:
#   gem: right-aws
#   gem: sensu-plugin
#
# USAGE:
#   ./check-elb-health.rb --elb-name MyELB
#
# NOTES:
#
# LICENSE:
#   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 'net/http'
require 'uri'
require 'right_aws'

class ELBHealth < Sensu::Plugin::Check::CLI
  option :aws_access_key,
         short: '-a AWS_ACCESS_KEY',
         long: '--aws-access-key AWS_ACCESS_KEY',
         description: "AWS Access Key. Either set ENV['AWS_ACCESS_KEY'] or provide it as an option",
         default: ENV['AWS_ACCESS_KEY']

  option :aws_secret_access_key,
         short: '-k AWS_SECRET_KEY',
         long: '--aws-secret-access-key AWS_SECRET_KEY',
         description: "AWS Secret Access Key. Either set ENV['AWS_SECRET_KEY'] or provide it as an option",
         default: ENV['AWS_SECRET_KEY']

  option :aws_region,
         short: '-r AWS_REGION',
         long: '--aws-region REGION',
         description: 'AWS Region (such as eu-west-1). If you do not specify a region, it will be detected by the server the script is run on'

  option :elb_name,
         short: '-n ELB_NAME',
         long: '--elb-name ELB_NAME',
         description: 'The Elastic Load Balancer name of which you want to check the health',
         required: true

  option :instances,
         short: '-i INSTANCES',
         long: '--instances INSTANCES',
         description: 'Comma separated list of specific instances IDs inside the ELB of which you want to check the health'

  option :verbose,
         short: '-v',
         long: '--verbose',
         description: 'Enable a little bit more verbose reports about instance health',
         boolean: true,
         default: false

  def query_instance_region
    instance_az = nil
    Timeout.timeout(3) do
      instance_az = Net::HTTP.get(URI('http://169.254.169.254/latest/meta-data/placement/availability-zone/'))
    end
    instance_az[0...-1]
  rescue StandardError
    raise "Cannot obtain this instance's Availability Zone. Maybe not running on AWS?"
  end

  def run
    begin
      aws_region = config[:aws_region].nil? || config[:aws_region].empty? ? query_instance_region : config[:aws_region]
      elb = RightAws::ElbInterface.new(config[:aws_access_key], config[:aws_secret_access_key],
                                       logger: Logger.new('/dev/null'),
                                       cache: false,
                                       server: "elasticloadbalancing.#{aws_region}.amazonaws.com")
      if config[:instances]
        instances = config[:instances].split(',')
        health = elb.describe_instance_health(config[:elb_name], instances)
      else
        health = elb.describe_instance_health(config[:elb_name])
      end
    rescue StandardError => e
      critical "An issue occured while communicating with the AWS EC2 API: #{e.message}"
    end
    # #YELLOW
    unless health.empty? # rubocop:disable UnlessElse
      unhealthy_instances = {}
      health.each do |instance|
        unhealthy_instances[instance[:instance_id]] = instance[:state] unless instance[:state].eql?('InService')
      end
      # #YELLOW
      unless unhealthy_instances.empty? # rubocop:disable UnlessElse
        if config[:verbose]
          critical "Unhealthy instances detected: #{unhealthy_instances.map { |id, state| '[' + id + '::' + state + ']' }.join(' ')}"
        else
          critical "Detected [#{unhealthy_instances.size}] unhealthy instances"
        end
      else
        ok "All instances on ELB #{aws_region}::#{config[:elb_name]} healthy!"
      end
    else
      critical 'Failed to retrieve ELB instance health data'
    end
  end
end