It worked! Thanks for the hint with the file location and if dracut or the initramfs contains/is visible the file at all.
I have now carried out the following steps:
- create own .conf file to assign the password file
nano /etc/dracut.conf.d/luks-keys.conf - entry of the path to the password file
install_items+=" /etc/luks-keys/passwort " - update the initramf
sudo dracut -f - check if the file appears in initrmfs
sudo lsinitrd | less
For completion here the entry in /etc/crypttab:
<name> <uuid> /etc/luks-keys/passwort discard
@Ritov thanks for the hint with the pictures.