Managing Node.js - Express Sessions with Redis
Article Summary: Learn how & why you should use Redis in-memory database storage for scalable Node.js / Express application session management (because the express-session store is not scalable).
Overview
If you have ever created a local Node.js / Express application that uses session variables for data persistence (i.e. req.session), then you have probably used the express-session library that comes along with most boilerplate Express server configurations.
You may have also noticed that the express-session docs explicitly state the following:
Warning The default server-side session storage,
MemoryStore, is purposely not designed for a production environment. It will leak memory under most conditions, does not scale past a single process, and is meant for debugging and developing.
If you have never been exposed to production application architecture, then this information might confuse you a bit. It is assuming that we probably have multiple instances of our application running (and perhaps on multiple boxes) under a load balancer like NGINX that is taking some kind of round-robin approach to fulfilling client requests.
With a setup like this, a typical user journey may comprise of the following:
