app.lua

-- app.lua

local lapis = require('lapis')
local json_params = require('lapis.application').json_params

local cjson = require('cjson')

local api_url = assert(os.getenv('API_URL'), "Missing API_URL environment variable")
local chat_id = assert(os.getenv('CHAT_ID'), "Missing CHAT_ID environment variable")
local bot_token = assert(os.getenv('BOT_TOKEN'), "Missing BOT_TOKEN environment variable")
local icons = { fire = '\xF0\x9F\x94\xA5', smile = '\xF0\x9F\x98\x83' }
local uri = api_url .. 'bot' .. bot_token .. '/sendMessage'

local app = lapis.Application()

app:get('/', function(self)
	return {
		json = {
			name = "levar",
			version = 0.1
		}
	}
end)

app:post('/', json_params(function(self)

	local alert = self.params

	local httpc = require("resty.http").new()
	httpc:set_proxy_options({
		http_proxy = os.getenv('HTTP_PROXY'),
		https_proxy = os.getenv('HTTPS_PROXY'),
		no_proxy = os.getenv('NO_PROXY')
	})

	if next(alert) == nil then
		ngx.log(ngx.NOTICE, 'Empty body received, ignoring.')
		return { json = { message = 'Empty body received, ignoring.' } }
	end

	for k,v in ipairs(alert.alerts) do
		ngx.log(ngx.NOTICE, cjson.encode(v))
		local status = v.status == 'firing' and icons.fire or icons.smile
		local res, err = httpc:request_uri(uri, {
			method = "POST",
			body = cjson.encode({
				chat_id = chat_id,
				parse_mode = 'Markdown',
				text = string.format('*%s* %s\n*Where:* %s\n%s',
					v.labels.alertname,
					status,
					v.labels.namespace or v.labels.node or 'cluster',
					v.annotations.summary or v.annotations.message:match('^.-%.%s') or v.annotations.message:match('^.+%.$')
				)
			}),
			headers = {["Content-Type"] = "application/json"},
			ssl_verify = false
		})
		if not res then
			httpc:close()
			ngx.log(ngx.ERR, err)
			return {{ json = err }, status = 500 }
		elseif res.status ~= 200 then
			httpc:close()
			ngx.log(ngx.ERR, res.body)
			return { json = res.body, status = res.status }
		end
	end

	httpc:close()
	return { json = { message = 'Alert sent.' } }
end))

function app:handle_error(err, trace)
	ngx.log(ngx.ERR, err, trace)
	return { json = {message = 'An error happened, please see the logs'}, status = 500 }
end

return app