Can't overwrite NixOS installation USB drive?

[axelsimon]

I'm trying to install NixOS using nixos-anywhere to a single-board computer booted with:

• Tow-Boot on a SD card
• the default (UEFI) arm64 installer, on a USB drive (NixOS unstable, new kernel installer image, as suggested on https://nixos.wiki/wiki/NixOS_on_ARM/UEFI)

As far as I understand, this fits the requirements.

I run nix run github:nix-community/nixos-anywhere -- --disk-encryption-keys /tmp/secret.key <(pass computers/my-sbc/LUKS) --flake '.#my-sbc' root@my-sbc which starts running fine and starts configuring disks with disko but fails at this step.

One one hand, i get that this is attempting to saw the branch i'm sitting on. I can see in the logs:

+ umount -R /iso
umount: /iso: target is busy.

while mount shows: /dev/sda on /iso type iso9660 (ro,relatime,nojoliet,check=s,map=n,blocksize=2048)

Finally we hit:

mkfs.vfat: unable to open /dev/disk/by-partlabel/disk-usb-drive-ESP: Device or resource busy

But on the other hand, i thought this was the point: boot an install medium, get ssh going, start installing.

Does this mean you really need two drives to run nixos-anywhere, one to boot the installation image, and one as the target drive? Or am i just missing something?

[axelsimon]

Just saw that the "system requirement" mention "Nixos-anywhere does not support wifi networks." is that actually true? In this case, the SBC is reachable over wifi but SSH works fine, which meets the requirement just before the wifi line: "The machine must be reachable over the public internet or local network." Not sure it would have anything to do with the issue at hand, but i'd rather be transparent.