I want to be able to serve content from the Pi’s internal SD card.
Raspberry Digital Signage admin interface allows you to type in the URL of the web resource to be displayed; it can be an Internet one (https://www.binaryemotions.com), a LAN URL (http://192.168.1.100/booking; http://booking.lan), or even a resource located internally, inside the Raspberry Pi’s filesystem.
To simplify the management of the internal site setup, the WordPress plugin adds a WordPress installation to the system (/rds/var/www/wordpress).
DIY SITE INSTALLATION
If you however want to add your own site (and/or don’t use the WordPress installation), just copy your website files inside the system to /rds/var/www/mySite as it was a “normal” webserver, change the ownership:
chown -R rds-www:rds-www /rds/var/www/mySite
and set the URL: http://127.0.0.1/mySite in the admin interface.
Also, you need to allow your www folder to be reached without authentication; add the following to /etc/apache2/sites-enabled/rds.conf:
SetEnvIf Request_URI ^/mySite.* noauth=1
This way you can natively serve plain HTML and PHP files.
You can copy files into the Raspberry Pi with (win)scp or simply by linking a Dropbox/Google Drive resource and using wget Linux-side in order to download the compressed archive.
Disable network check
Upon boot, the system checks for the availability of the network, in order to display the proper admin interface if no network is available. However, with an internal site installation, the network check could be unwanted: in case, modify /rds/home/rds-user/.xinitrc as: