Ordering units and targets with devices

[Michael Cassaniti <michael@xxxxxxxxxxxxxxx>]

Hi,

I'm trying to order my units and targets during early boot so that:
1. A symlink to the specific FIDO2 token I'm using gets created. I 
already have a udev rule in place for this and it successfully creates 
the symlink under /dev. Because I have two tokens I need to specify 
which one to use.
2. The unit for systemd-cryptsetup@root.service has to wait for this 
unit. The unit gets generated from systemd-cryptsetup-generator so I 
can't just add Requires= stanzas to the unit. I do have a /etc/crypttab 
file.

I have the following shell code generating everything a the right time 
within dracut, but this hasn't solved my problem.

    cat > /etc/systemd/system/dev-yubico\x2dfido2.device << EOF
    [Unit]
    Description=Device for Yubico FIDO2 token
    DefaultDependencies=no
    RequiredBy=cryptsetup-pre.target

    [Install]
    WantedBy=cryptsetup-pre.target

    EOF

    systemctl enable dev-yubico\x2dfido2.device
    systemctl add-wants cryptsetup.target cryptsetup-pre.target


Any help here is appreciated. The issue is that the FIDO2 token shows up 
on the USB bus after the disk is detected and the unit 
systemd-cryptsetup@root.service starts. I don't have a TPM2 chip so that 
rules out using a TPM instead.

Thanks in advance,
Michael Cassaniti, Australia

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