For a while now I've been wanting an NGINX with chroot option:

1. create a new chroot for NGINX
   • especially if you can take advantage of some underlying COW semantics, e.g. zfs, btrfs, overlayfs
2. test the new config nginx --chroot=/var/lib/nginx/chroots/$UUID -t /etc/nginx/nginx.conf
3. tell nginx to pivot and reload nginx --chroot=/var/lib/nginx/chroots/$UUID -- this can no longer be a simple SIGHUP.

But this would make these tasks so easy to do-- we can prepare the new space, and if it doesn't work there's no trying to copy files back into the right location.

I've been thinking maybe we could do this with a eBPF program that intercepts open calls to rewrite the path to the desired chroot and then step 3 becomes 1. replace the eBPF, 2. SIGHUP. Would need to ensure the newly forked workers receive the new eBPF and bonus points if the old workers maintain the chroot/eBPF-rewrite until they die.