Control the entire configuration with an ENV variable

[spawnia]

Motivation

I frequently need to change configuration values other then the ones that are currently provided via ENV variables. However, mounting a volume is very inconvenient when deploying the container to a cluster. My solution so far has been to build a seperate image with the configuration baked in.

Idea

How about we just allow the user to put in any configuration in a new ENV variable called PMA_CONFIG and then just do the following in config.inc.php:

if (isset($_ENV['PMA_CONFIG'])) {
    eval($_ENV['PMA_CONFIG']);
}

So the container could be run like this:

docker run -p 80:80 -e PMA_CONFIG='$cfg["SomeObscureConfig"] = "foobar";' phpmyadmin

That would allow the user to use any configuration option, without supplying a file - and without us having to do mapping for each and every single option.

Caveats

We would have to provide a section on how to properly escape code in env variables. I did
not get to do much experimentation yet, because the local docker build is failing for me.
But i foresee that some special chars like $'"& might be troublesome.