Use req.get('host') to properly pick up x-forwarded headers.

src/addon/src/serverless.js

@@ -43,7 +43,7 @@ router.get('/:configuration?/:resource/:type/:id/:extra?.json', limiter, (req, r
   const { configuration, resource, type, id } = req.params;
   const extra = req.params.extra ? qs.parse(req.url.split('/').pop().slice(0, -5)) : {}
   const ip = requestIp.getClientIp(req);
-  const host = `${req.protocol}://${req.headers.host}`;
+  const host = `${req.protocol}://${req.get('host')}`;
   console.log(`Host is ${host}`);
   const configValues = { ...extra, ...parseConfiguration(configuration), id, type, ip, host };
   addonInterface.get(resource, type, id, configValues)