gw_monitor.lua

--- Service for FusionPBX to monitor on gateway status
-- and send email notification when gateway change its status.
--
-- Require FusionPBX 4.3 or higher
--
-- start: `fs_cli -x 'luarun gw_monitor.lua'`
-- stop: `fs_cli -x 'lua service gw_monitor stop'`
-- pid file: `${script_dir}/run/gw_monitor.pid`

local email        = 'mail@address'
local service_name = 'gw_monitor'

----------------------------------------------------

require "resources.functions.config"

local log               = require "resources.functions.log"[service_name]
local send_mail         = require "resources.functions.send_mail"
local Database          = require "resources.functions.database"
local BasicEventService = require "resources.functions.basic_event_service"

local get_gw_info_sql = [[select d.domain_name, d.domain_uuid, g.gateway
from v_gateways as g left outer join v_domains as d on d.domain_uuid = g.domain_uuid
where g.gateway_uuid=:gateway_uuid]]

local function get_gw_info(name)
	local dbh = Database.new('system')
	if not dbh then return end
	local row = dbh:first_row(get_gw_info_sql, {gateway_uuid = name})
	dbh:release()
	if not row then return end
	return row.gateway, row.domain_name, row.domain_uuid
end

local service = BasicEventService.new(log, service_name)

local known = {}
service:bind("CUSTOM::sofia::gateway_state", function(self, name, event)
	-- log.notice(event:serialize('plain'))

	local gateway = event:getHeader('Gateway')
	local state   = event:getHeader('State')

	local title
	if state == 'FAILED' then
		if known[gateway] == 'FAILED' then
			return
		end
		title = 'ALERT - Gateway is DOWN: '
	elseif state == 'REGED' then
		if known[gateway] == 'REGED' then
			return
		end
		title = 'ALERT - Gateway is UP: '
	else
		-- ignore other states
		return
	end
	known[gateway] = state

	local ping    = event:getHeader('Ping-Status')
	local status  = event:getHeader('Status')
	local phrase  = event:getHeader('Phrase')

	local gateway_name, domain_name, domain_uuid = get_gw_info(gateway)
	if not gateway_name then return end

	local full_name = gateway_name
	if #domain_name > 0 then full_name = full_name .. '@' .. domain_name end

	local response = status or ''
	if status and phrase then -- this is SIP response
		response = ' ' .. status .. ' ' .. phrase
	end

	local msg = string.format("%s state %s%s ping: %s", full_name, state, response, ping or '')

	log.notice(msg)

	local headers = {}
	headers["X-FusionPBX-Email-Type"]  = 'gateway-monitor'
	if #domain_name > 0 then
		headers["X-FusionPBX-Domain-UUID"] = domain_uuid
		headers["X-FusionPBX-Domain-Name"] = domain_name
	end
	send_mail(headers, email, {
		title .. ' ' .. full_name,
		os.date('%Y-%m-%d %H:%M:%S') .. ' ' .. msg
	})
end)

log.notice("start")

service:run()

log.notice("stop")

I like this, it works great. I modified line# 78 and 84 to read: 'ALERT - Gateway is DOWN: ' .. full_name; and 'ALERT - Gateway is UP: ' .. full_name; respectively.
Makes the grammar sound better I think.

hey bud, so I tried the updated code and it fired an email once. It's now 24 hours and it hasn't generated another one.