This image is derived from the [Instrumentisto Roundcube Image](https://hub.docker.com/r/instrumentisto/roundcube/)
It works in everything like the parent image, being the main difference that you can add plugins to be installed at boot time in the file */app/composer.json*.
Basically, what I do, is to create a *Docker Config* with the composer.json content and mount it on the unformentioned directory. Something like this:
This way, you can install the plugins you want for your Roundcube instalation.
If the installed plugins need some configuration files, you can place them under */plugins_config/*. So,for example, if your *authres_status* plugin needs a configuration file (Hint: it does), you can place it on */plugins_config/authres_status/config.php* and the startup script will take care of the rest.