What you'll have at the end

Your deployed app reading and writing through the managed database's real connection string

Before you start

You need

A deployed Express API whose Postgres client still points at your own machine's local settings, and a managed Postgres database already created with your provider, its tables already set up to match your local schema.

Not covered

Creating the tables inside the managed database in the first place.

Leans on

Express.js Cheat SheetHas the exact Pool config line you're about to rewrite, plus how process.env already works in your app.
Node.js Cheat SheetCovers what process.env actually holds and where a value in it comes from.
Full-Stack Application Deployment Cheat SheetLists the hosts with their own connection-string and environment-variable screens, if yours works differently than described here.
PostgreSQL Cheat SheetYour database's own query reference, for the final check once you're reading straight from it.

Where to go next

Store secrets as host environment variables

go there first if you've never set a variable on your host before; this recipe assumes you already know how

Add a health check endpoint

go there once you want your host itself, rather than only your own eyes, to catch a broken connection automatically

Your app still points at a local Postgres instead of the managed one

Before you start

Where to go next

Your app still points at a local Postgres instead of the managed one

Before you start

Where to go next