Meteor.startup(() => { if (process.env.CORS) { // Listen to incoming HTTP requests, can only be used on the server WebApp.rawConnectHandlers.use(function(req, res, next) { res.setHeader('Access-Control-Allow-Origin', process.env.CORS); return next(); }); } if (process.env.CORS_ALLOW_HEADERS) { WebApp.rawConnectHandlers.use(function(req, res, next) { res.setHeader( 'Access-Control-Allow-Headers', process.env.CORS_ALLOW_HEADERS, ); return next(); }); } if (process.env.CORS_EXPOSE_HEADERS) { WebApp.rawConnectHandlers.use(function(req, res, next) { res.setHeader( 'Access-Control-Expose-Headers', process.env.CORS_EXPOSE_HEADERS, ); return next(); }); } });