For further considerations on deploying web apps, see The Twelve-Factor App (http://12factor.net/). This is a detailed resource about important considerations for running enterprise-grade web applications on services such as Heroku.

There are, of course, a great many options for hosting a web application. Azure's web app service and AWS's Elastic Beanstalk both support Node.js as a first-class citizen. Modulus (https://modulus.io/) provides Node.js and Mongo DB hosting, with powerful scaling, monitoring, and load-balancing features.

The preceding are all examples of application hosting platforms (Platform-as-a-Service (PaaS), in cloud terminology). You can, of course, also deploy Node.js applications to bare infrastructure (either cloud infrastructure or your own machines). For a detailed guide, see https://certsimple.com/blog/deploy-node-on-linux.

You may need to manage releases of your application through multiple environments. Your CI server might first deploy your application...