Question about Enhance containerisation?

webquest

I understand that Enhance uses some kind of containerisation which I presume is for added security and/or setting fine grained resource limits.

What I am wondering, however, is whether there are any significant downsides to this. For instance does it mean permanently committing a slice of RAM to a website even though it may not be a high usage website?

Adam

Enhance PHP workers are containerised but this is implemented at a kernel level with the PHP SAPI as PID 1 so there is almost zero overhead for this. You su or ssh directly into the customer's website container, just like you can on legacy panels.

There is always one PHP worker per website but this isn't related to the PHP containerisation. In the future we may be able to complete shut down the PHP SAPI for idle websites. If we implement this, it will be a platform setting.

webquest

Does that mean when a PHP website is idle it is only using minimal RAM or does it hold on to the RAM that was allocated from previously long forgotten requests? I am trying to figure out how much RAM is committed to the containerised PID 1.

Adam

webquest

The default configuration for PHP-FPM and LSPHP will scale down to a single worker if the website is idle. The spare processes exit and do not hold on to any memory. This isn't related to the containerisation.

webquest

What about processes for websites that have a slow memory leak over time? Can these be automatically restarted once their ram usage gets too high?

Adam

Enhance doesn't do that but you can set hard resource limits on each website to prevent memory overrun. You can set a package level setting and override it for any websites you want to give more or less resources to.