This is a really barebones PHP+MySQL docker setup.

Make sure you have installed Docker for Mac or Windows (if you use either of
those).  Seriously, get the "..for Mac" (or Windows) version, it comes with
additional tools you'll need and doesn't rely on VirtualBox.

To fire this up, run the following command:

    docker-compose up

That'll start it in "attached" mode where you later have to hit ctrl-c to
stop everything.  If you prefer to run it in "detached mode" you can run:

Put your PHP code in the "src" directory.  To view itin your browser, just
go to http://localhost

In your PHP code, you can use the following database credentials:

    hostname: db_1
    username: root
    password: root

If you want to connect directly to your database with a local tool, such as
MySQL Workbench, you can use the following credentials:

    hostname: localhost
    username: root
    password: root

If for some reason you have to rebuild your PHP container, you can do so
with the following commands:

    docker images

...look at the output to find the name of your image.  Probably it'll be
yourproject_php

    docker rm [name of your project]_1
    docker rmi [name of your project]