add endpoint for LetsEncrypt verification and environment variables

lib/index.js

@@ -10,6 +10,8 @@ const generateICS = require('./ics')
 const { genericErrorHandler, checkURLParameter } = require('./middlewares')
 
 const port = process.env.PORT
+const certEndpoint = process.env.CERT_ENDPOINT || ''
+const certSecret = process.env.CERT_SECRET
 const app = express()
 
 app.set('view engine', 'ejs')
@@ -19,6 +21,10 @@ app.use(express.static(path.join(__dirname, 'public')))
 app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')))
 app.use(bodyParser())
 
+app.get(`/${certEndpoint}`, (req, res) => {
+  res.status(200).send(certSecret)
+})
+
 app.get('/', (req, res) => {
   res.render('index')
 })