The underlying cause of this appears to be a missing dependency. Dracut doesn't include cryptsetup in the initrd if systemd is used within the initrd - in that instance it requires systemd-cryptsetup. systemd-cryptsetup is not installed by default when one installs dracut, leaving the user with no way of decrypting their disk on next reboot.
Installing systemd-cryptsetup and then making dracut regenerate the initrd fixes the issue - the user now gets a prompt to type their decryption passphrase at. (Granted, it's not a very *clear* prompt - all you see is a gray rectangle that looks vaguely like a text box, with no text or other indicator that you're supposed to type your disk's passphrase there. But, it's *a* prompt at least.) To reproduce the fix: * Download the latest Debian Testing XFCE live ISO * Boot it in VirtualBox * Install Debian with manual partitioning, creating an unencrypted /boot directory and an encrypted root directory * Reboot into the installed system, decrypting with your passphrase when prompted * Take a snapshot * Install dracut - `sudo apt install dracut` * Reboot, see that you never get a prompt to decrypt the disk * Restore the snapshot you made earlier * Install dracut - `sudo apt install dracut` * Install systemd-cryptsetup - `sudo apt install systemd-cryptsetup` * Reconfigure dracut to regen the initrd - `sudo dpkg-reconfigure dracut` * Reboot, see that you get a prompt now * Enter your disk passphrase * System should boot successfully This probably just requires systemd-cryptsetup to be added as a dependency of dracut. I'll test it out, if it works I'll try and submit the fix.
