| 29 May 2023 |
 @elvishjerricco:matrix.org | well | 01:28:42 |
| @elvishjerricco:matrix.org | the best thing to do is have After= on the specific device you want | 01:28:55 |
| @elvishjerricco:matrix.org | in an ideal world we'd have Lily Foster's patch and you could do After=initrd-root-device.target to wait for whatever the root fs's device is | 01:29:21 |
 Winter (she/her) | ah, okay | 01:29:30 |
| @elvishjerricco:matrix.org | but that's still not "all devices" since that's not really a thing in udev | 01:29:34 |
| Winter (she/her) | In reply to @elvishjerricco:matrix.org
the best thing to do is have After= on the specific device you want how do I find that? | 01:29:44 |
| @elvishjerricco:matrix.org | Winter (she/her): What specifically are you trying to do? We may have an X Y problem here | 01:30:05 |
| Winter (she/her) | ephemeral rootfs, so I kind of need that ordering | 01:30:39 |
| Winter (she/her) | not ZFS though, so I can't rely on the ZFS import services | 01:30:56 |
| @elvishjerricco:matrix.org | so how are you achieving ephemeral rootfs then? | 01:31:16 |
| Winter (she/her) | btrfs:
mkdir /scratch
mount /dev/mapper/nixos /scratch
btrfs subvolume delete /scratch/root/srv
btrfs subvolume delete /scratch/root/var/lib/portables
btrfs subvolume delete /scratch/root/var/lib/machines
btrfs subvolume delete /scratch/root
btrfs subvolume snapshot /scratch/root-blank /scratch/root
umount /scratch
rm -r /scratch
| 01:32:26 |
| Winter (she/her) | oh, i could use cryptsetup.target | 01:32:46 |
| @elvishjerricco:matrix.org | I se | 01:32:55 |
| @elvishjerricco:matrix.org | * I see | 01:32:56 |
| @elvishjerricco:matrix.org | no, | 01:32:57 |
| @elvishjerricco:matrix.org | You probably just want to do After=dev-mapper-nixos.device | 01:33:20 |
| Winter (she/her) | ah, yeah, that'd be better | 01:33:29 |
| @elvishjerricco:matrix.org | and BindsTo=dev-mapper-nixos.device | 01:33:34 |
| @elvishjerricco:matrix.org | with that combination, that's how systemd does the "waiting for device blabla..." thing | 01:33:53 |
| Winter (she/her) | so like this?
boot.initrd.systemd.services.wipe-root = {
wantedBy = [ "initrd.target" ];
before = [ "sysroot.target" ];
after = [ "dev-mapper-nixos.device" ];
bindsTo = [ "dev-mapper-nixos.device" ];
path = [ pkgs.coreutils pkgs.btrfs-progs ];
serviceConfig.Type = "oneshot";
script = ''
mkdir /scratch
mount /dev/mapper/nixos /scratch
btrfs subvolume delete /scratch/root/srv
btrfs subvolume delete /scratch/root/var/lib/portables
btrfs subvolume delete /scratch/root/var/lib/machines
btrfs subvolume delete /scratch/root
btrfs subvolume snapshot /scratch/root-blank /scratch/root
umount /scratch
rm -r /scratch
'';
};
| 01:36:19 |
| @elvishjerricco:matrix.org | s/sysroot.target/sysroot.mount/ | 01:37:04 |
| @elvishjerricco:matrix.org | * s/sysroot.target/sysroot.mount/ | 01:37:06 |
| Winter (she/her) | thanks. | 01:37:28 |
| @elvishjerricco:matrix.org | and it might be technically more correct to say requiredBy = ["sysroot.mount"]; rather than wantedBy = ["initrd.target"];? Which unit probably doesn't matter in all practicality, but wantedBy vs requiredBy just dictates whether you want failure to turn into a total stage 1 failure | 01:38:10 |
| Winter (she/her) | requiredBy = [ "sysroot.mount" ];
# before = [ "sysroot.mount" ];
| 01:38:41 |
| Winter (she/her) | do I need to keep before then? | 01:38:46 |
| @elvishjerricco:matrix.org | still need the before. Requires dependencies don't cause runtime ordering | 01:39:07 |
| Winter (she/her) | got it, wasn't 100% sure | 01:39:29 |
| @elvishjerricco:matrix.org | and only lead to failure if the required unit fails before the requiring unit has even started | 01:39:31 |
| Winter (she/her) | interesting | 01:39:49 |
