Forty client sites, forty PHP versions, one server

The agency's shared hosting account runs one PHP version. Upgrading it for the new client breaks three old ones. Not upgrading it means the new client's framework won't install. You've kept a spreadsheet of which site tolerates which PHP since 2022.

On Hoody each client site is a container with its own runtime: this one on PHP 7.4 because its plugin set won't move, that one on 8.3 because it's new. Forty sites, forty interpreters, forty isolated filesystems, one bare metal box. A site getting a hundred visits a day is idle the rest of it: no CPU, disk shared copy-on-write with the stack template. Forty VPSes would have been the honest fix; forty VPSes was the bill that kept you on shared hosting.

The runtime stopped being a server-wide decision and became a per-client one.