Hardcoded cache $prefix makes it impossible to find keys from different hosts

[GhaziTriki]

Hello,

We have following configuration. We have an F3 application that have pseudo-CDN feature under /cdn/*. We have added a redirection in .htaccess from /cdn/* to cdn.domain.com/*. It results in different cache prefixes and keys added in main domain cannot be found in subdomain. And it does not work because of the following line.

https://github.com/bcosca/fatfree-core/blob/64976a57729024657cd7ee4cc01ea7f74d5b0e43/base.php#L2462

A good example, one of our keys is avatar.user.60.90x90
Cache prefix is $this->prefix . $key;
In cdn.domain.com : $this->prefix = 'h6qqa2jvtoez';
In domain.com : $this->prefix = '3awbd3dh8n400';

Cache $prefix should be configurable and should not be hardcoded.

[ikkez]

Hi. The used application specific hash is now globally configurable with the new $f3->SEED var.

[GhaziTriki]

Hi, good idea for the implementation. It should be added to the official documentation.

[ptdev]

Hey, just came across a similar issue and had to set this variable.

It should be stated that one should set the SEED variable before setting the CACHE variable, otherwise it won't work.