On the DigitalOcean community blog they've posted a guide to setting up a LEPP server (Linux, Nginx, PHP and PostgreSQL) on a CentOS 7 instance (not specific to their own platform either, can be applied anywhere).

In this tutorial, we will create a simple web application in a two-tier architecture. Our base operating system for both nodes will be CentOS 7. The site will be powered by an Nginx web server running PHP code that talks to a PostgreSQL database. Instead of adopting a "top-down" approach seen in other LAMP or LEMP tutorials, we will use a "ground-up" approach: we will create a database tier first, then the web server and then see how the web server can connect to the database. We will call this configuration a LEPP (Linux, Nginx, PHP, PostgreSQL) stack.

They create a two-tier setup that involves the use of two CentOS systems (with examples from their own hosting options) and walk you through:

• Installing PostgreSQL
• Configuring PostgreSQL
• Updating the Database Server Firewall
• Creating and Populating the Database
• Installing Nginx
• Updating the Web Server Firewall
• Configuring Nginx
• Installing PHP
• Configuring PHP
• Creating the Web Application

It seems like a lot of steps but all of the necessary commands and configuration updates are included in each step so it's basically a copy and paste kind of walk-through.