Rocket.Chat/app/blockstack/server/routes.js

import { Meteor } from 'meteor/meteor';
import { WebApp } from 'meteor/webapp';

import { settings } from '../../settings';
import { RocketChatAssets } from '../../assets/server';

WebApp.connectHandlers.use('/_blockstack/manifest', Meteor.bindEnvironment(function(req, res) {
	const name = settings.get('Site_Name');
	const startUrl = Meteor.absoluteUrl();
	const description = settings.get('Blockstack_Auth_Description');
	const iconUrl = RocketChatAssets.getURL('Assets_favicon_192');

	res.writeHead(200, {
		'Content-Type': 'application/json',
		'Access-Control-Allow-Origin': '*',
	});

	res.end(`{
    "name": "${ name }",
    "start_url": "${ startUrl }",
    "description": "${ description }",
    "icons": [{
      "src": "${ iconUrl }",
      "sizes": "192x192",
      "type": "image/png"
    }]
  }`);
}));