A very quick Nagios Plugin to check the overall status of an ESXi Host using rbvmomi.

Readme.md

Overview

This is a quick nagios plugin / script to query an ESXi server and grab the "overall status" parameter. This is a parameter each host should respond to and will reflect if any alarms are active on the system. See the official documentation for more info.

This should give notice in the event of a power supply failure, memory errors, loss of connectivity to datastore, etc.

The script only requires a Hostname, but allows for the providing of both a hostname and IP address. The hostname is required to make sure that the status being returned is for the correct host (I don't trust CIM to always return the hosts inside the "hostFolder" in the same order). It is actually used to query the API for the provided string, so it must be accurate and reflect what the system thinks its hostname is. Our environment and conditions mandated this. YMMV.

Parameters

Takes several parameters:

• Hostname
• IP Address
• Port
• CIM Username
• CIM Password
• Don't use SSL
• Don't check certs

Run the script with -h to see the switches and what they do (or you can just look at the code).

Nagios

Object definitions for Nagios configs would look something like this:

define command {
  command_name    check_esxi_host_status
  command_line    $USER1$/contrib/check_esxi_status.rb -H $HOSTNAME$ -I $HOSTADDRESS$ -U $_HOSTCIM_USER$ -P '$_HOSTCIM_PASS$' -S
}

define service {
  use                             generic-service
  hostgroup_name                  esxi-hosts
  contacts                        everybody
  service_description             ESXi Host Health
  check_command                   check_esxi_host_status
  servicegroups                   vmware-health-checks
}

Script output will look something akin to this:

OK: host1.vcenter.domain.tld reports green; The host is healthy.

check_esxi_status.rb

#!/usr/bin/ruby
######################################################################################################
#
# Description:
#  Query an ESXi Server using rbvmomi to check the overallStatus parameter
#
######################################################################################################
#
# Author: Nick Peelman (2016-11-08)
#
######################################################################################################
#
# Usage:
#  check_esxi_status.rb -H <hostname> -U <username> -P <password> --ignore-cert
#
######################################################################################################
#
# Requirements
# * gem install rbvmomi
#
######################################################################################################

require 'optparse'
require 'rbvmomi'

######################################################################################################

# https://www.vmware.com/support/developer/vc-sdk/visdk400pubs/ReferenceGuide/vim.ManagedEntity.Status.html
HEALTH_STATUSES = {
  gray: {
    exit_code: 3,
    status: "UNKNOWN",
    message: "The host repots that its health is unknown.",
  },
  green: {
    exit_code: 0,
    status: "OK",
    message: "The host is healthy.",
  },
  red: {
    exit_code: 2,
    status: "CRITICAL",
    message: "The host is reporting a problem.",
  },
  yellow: {
    exit_code: 1,
    status: "WARNING",
    message: "The host is reporting a possible problem.",
  },
}

######################################################################################################

@hostname = nil
@ipaddress = nil
@port = 443
@username = nil
@password = nil
@use_ssl = true
@ignore_cert = false

def parse_args(args = {})
  @opts = OptionParser.new
  @opts.on('-H', "--host HOSTNAME", "Hostname of the ESXi Server") do |hostname|
    @hostname = hostname
  end
  @opts.on('-I', "--ip-address ADDRESS", "IP Address of the ESXi Server") do |ipaddress|
    @ipaddress = ipaddress
  end
  @opts.on("-U", "--username USERNAME", "Username") do |username|
    @username = username
  end
  @opts.on("-P", "--password PASSWORD", "Password") do |password|
    @password = password
  end
  @opts.on("-p", "--port", "TCP port to use") do |port|
    @port = port
  end
  @opts.on("-s", "--no-ssl", "Don't use SSL") do
    @use_ssl = false
  end
  @opts.on("-S", "--ignore-cert", "Don't validate certificate") do
    @ignore_cert = true
  end
  @opts.on_tail("-h", "--help", "Show this message") do
    puts @opts
    exit
  end
  @opts.parse!
end

def get_host(vim)
  vim.serviceInstance.find_datacenter.hostFolder.findByDnsName(@hostname, RbVmomi::VIM::HostSystem)
end

def get_status(host)
  host.overallStatus
end

def get_host_name(vim)
  get_host(vim).name
rescue NoMethodError
  puts "SCRIPT_ERROR: Hostname not found; host at that IP might not match the hostname provided"
  exit 3
end

def get_vim
  connect_to = @ipaddress
  connect_to ||= @hostname
  vim = RbVmomi::VIM.connect({
    host: connect_to,
    port: @port,
    user: @username,
    password: @password,
    ssl: @use_ssl,
    insecure: @ignore_cert
  })
rescue Errno::ECONNREFUSED
  puts "UNKNOWN: Host is refusing to talk to us"
  exit 3
end

parse_args()

vim = get_vim()
name = get_host_name(vim)
status_color = get_status(get_host(vim))
nagios_output = HEALTH_STATUSES[status_color.to_sym]

output = "#{nagios_output[:status]}: #{name} reports #{status_color}; #{nagios_output[:message]}"

puts output