Scaling a LAMP app using Docker Containers - simple code and architectural discussion

As the journey to the cloud and containerization continues, and the quest to scale and leverage these technologies in production gains momentum, I wanted to share my perspectives on how to scale a simple LAMP-stack web app using containers.

The simple PHP code in this app lets you upload a file and share its link with someone else.

More than the code-base itself (which has some minor points of interest), I want to draw your attention to the following architectural discussion (all in README):

Enjoy, and please provide feedback and suggestions!