In reply to @nakibrayane:matrix.org

{
  disko.devices.disk.main = {
    type = "disk";
    device = "/dev/nvme0n1";
    content = {
      type = "gpt";
      partitions = {
        ESP = {
          size = "512M";
          type = "EF00";
          content = {
            type = "filesystem";
            format = "vfat";
            mountpoint = "/boot";
            mountOptions = [ "umask=0077" ];
          };
        };
        luks = {
          size = "100%";
          content = {
            type = "luks";
            name = "crypted";
            content = {
              type = "btrfs";
              extraArgs = [ "-f" ];
              subvolumes = {
                "/root" = {
                  mountpoint = "/";
                  mountOptions = [
                    "compress=zstd"
                    "noatime"
                  ];
                };
                "/nix" = {
                  mountpoint = "/nix";
                  mountOptions = [
                    "compress=zstd"
                    "noatime"
                  ];
                };
                "/swap" = {
                  mountpoint = "/.swapvol";
                  swap.swapfile.size = "7957M";
                };
              };
            };
          };
        };
      };
    };
  };
}

This is my disks setup.

Would this do it?

after = [ "systemd-cryptsetup@crypted.service" "systemd-hibernate-resume.service" ];

I figured it out:

  boot.initrd.systemd.services.rollback = {
    description = "Rollback BTRFS root subvolume to a pristine state";
    wantedBy = [ "initrd.target" ];
    after = [ "systemd-cryptsetup@crypted.service" ];
    before = [ "sysroot.mount" ];
    unitConfig.DefaultDependencies = "no";
    serviceConfig.Type = "oneshot";
    script = # bash
      ''
        mkdir /btrfs_tmp
        mount /dev/mapper/crypted /btrfs_tmp

        delete_subvolume_recursively() {
          IFS=$'\n'
          for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
            delete_subvolume_recursively "/btrfs_tmp/$i"
          done
          btrfs subvolume delete "$1"
        }

        if [[ -e /btrfs_tmp/root ]]; then
          delete_subvolume_recursively /btrfs_tmp/root
        fi

        btrfs subvolume create /btrfs_tmp/root
        umount /btrfs_tmp
      '';
  };

I always have trouble setting a systemd unit up correctly. I want to have a systemd unit that will always run AFTER another unit has started, but I ALSO want it to run, if the unit itself has changed. E.g. I have unit called lldap, and I want to run lldapprovision. So when lldap starts -> run lldapprovision. When lldapprovision changes -> run lldapprovision. I have the following right now.

      wantedBy = [ config.systemd.services.lldap.name ];
      after = [ config.systemd.services.lldap.name ];