First and foremost, database administration. Many PHP applications are heavily reliant on large amounts of data stored in MySQL databases, so understanding how to configure, test and debug MySQL / MariaDB databases and write SQL queries (without relying on frameworks) is essential. Knowing Linux (e.g. Ubuntu, Debian, Fedora distributions) on AWS and be able to fully interact by shell / command line is key. Equally, working with Apache and customizing Apache conf files and configurations for performance and security is critical to maintain code for communication between back end systems and customer-facing front end applications (such as Vue.js). Being able to code in PHP Legacy (from 7.2+) and OOP Object-Oriented Programming in PHP Legacy, outside of frameworks like Laravel is key. This ability will serve functional tasks such as Custom REST API Development, identifying and optimizing slow queries, monitoring table indexes and addressing maintenance issues with server CPU/memory usage, disk space, etc.
To be able to work with Drupal APIs and custom Drupal modules (Devel, Chaos Tools Suite - CTools, Views etc) and implement custom Drupal website builds; then knowledge of PHP, PHP files and theme functions, and knowledge of the Drupal theme layer is core. Without this PHP server-side language experience, it's not possible to create custom modules, run automated tests, use web services, and deploy Drupal software automatically. To manage Drupal site dependencies, setup API calls to retrieve objects and render objects for example in Drupal mapping; manage web hooks or consuming REST, JSON services, PHP expertise is essential.
Work within the PHP backend (Laravel, Symfony, Zend, MySQL, Rest) with continuous deployment on Linux-based AWS infrastructure and Test Driven Development (TDD). Experience working with Node.js REST frameworks like Express.js or Hapi.js and SaaS and microservice architectures are key here. Refactoring and removing spaghetti code are common tasks; as is increasing trust and security with validation and compatibility backend programming not least working in backend frameworks that support MVC for example: SailsJS, ROR (Ruby on Rails), PHP Symfony, Python Django, ASP.NET and EJB.