This tutorial is for creating a Debian chroot inside a system that has systemd fully implemented. This tutorial will not work on current Debian stable (jessie).

First we need to install some dependencies:

sudo pacman -S debootstrap

Depending on you distro, you may use aptitude install instead. Now that we have debootstrap, we can have a basic Debian installation.

sudo mkdir -p /var/chroot
sudo debootstrap --arch amd64 jessie /var/chroot http://ftp.us.debian.org/debian/

The chroot is now installed and fully functional.

In order to access the internal Debian, use:

sudo systemd-nspawn -D /var/chroot

This will let you to use Debian as root user. It is a bad idea to use root, so first setup a root password, and then create a user. Once this is done, you chroot is ready for everyday usage.