nixos-demo/os/persistence.nix

{ config, lib, ... }:

{
  environment.persistence = {
    persistence = {
      enable = lib.mkIf (config.beancloud.persistence.type != "impermanence") false;
      persistentStoragePath = "/nix/persistence";
      hideMounts = true;
      directories = [
        "/etc/nixos"
        "/var/log"
        "/var/lib/bluetooth"
        "/var/lib/nixos"
        "/var/lib/systemd/coredump"
        "/var/lib/systemd/timers"
        "/etc/NetworkManager/system-connections"
      ];
      files = [
        "/etc/machine-id"
        "/etc/ssh/ssh_host_rsa_key"
        "/etc/ssh/ssh_host_rsa_key.pub"
        "/etc/ssh/ssh_host_ed25519_key"
        "/etc/ssh/ssh_host_ed25519_key.pub"
      ];
    };
  };

  boot.initrd.preLVMCommands =
    lib.mkIf
      (config.beancloud.persistence.type != "preservation" && config.beancloud.persistence.root == "fs")
      ''
        WAIT_TIME=5
        MAX_RETRIES=6
        ROOT_DEV="/dev/disk/by-label/root"
        ROOT_DIR=/rootmnt"

        mountPartition() {
          echo "mount the root / partition"

          echo "create the $ROOT_DIR folder"
          mkdir -p "$ROOT_DIR"

          COUNTER=1
          while [ ! -e "$ROOT_DEV" ] || [ ! -e "$ROOT_DIR" ]; do
            echo "the root partition or the mount folder are not yet available"
            sleep $WAIT_TIME
            if [ "$COUNTER" -eq "$MAX_RETRIES" ]; then
              echo "device check failed"
              exit 1
            fi
            COUNTER="$((COUNTER + 1))"
          done

          COUNTER=1
          until mount "$ROOT_DEV" $ROOT_DIR; do
            echo "the root partition has not yet been mounted"
            sleep "$WAIT_TIME"
            if [ "$COUNTER" -eq "$MAX_RETRIES" ]; then
              echo "mount failed"
              exit 1
            fi
            COUNTER="$((COUNTER + 1))"
          done
          echo "mount done"
        }

        wipePartition() {
          echo "wipe the content from the / partition"

          COUNTER=1
          until rm -rf "$ROOT_DIR/*"; do
            echo "the wipe has been failed"
            sleep 5
            if [ "$COUNTER" -eq "$MAX_RETRIES" ]; then
              echo "wipe failed"
              exit 1
            fi
            COUNTER="$((COUNTER + 1))"
          done
          echo "wipe done"
        }

        umountPartition() {
          echo "umount the root / partition"

          COUNTER=1
          until umount "$ROOT_DIR"; do
            echo "umount failed"
            sleep 5
            if [ "$COUNTER" -eq "$MAX_RETRIES" ]; then
              echo "umount failed"
              exit 1
            fi
            COUNTER="$((COUNTER + 1))"
          done
          echo "umount done"
        }

        loadModules() {
          echo "load the ext4 module"

          COUNTER=1
          until modprobe ext4; do
            echo "modprobe ext4 failed"
            sleep 5
            if [ "$COUNTER" -eq "$MAX_RETRIES" ]; then
              echo "modprobe failed"
              exit 1
            fi
            COUNTER="$((COUNTER + 1))"
          done
          echo "modprobe done"
        }

        fixPermissions() {
          echo "fix /var/empty permissions"

          COUNTER=1
          until chattr -i -a "$ROOT_DIR/var/empty"; do
            echo "chattr /var/empty failed"
            sleep 5
            if [ "$COUNTER" -eq "$MAX_RETRIES" ]; then
              echo "chattr failed"
              exit 1
            fi
            COUNTER="$((COUNTER + 1))"
          done

          COUNTER=1
          until chmod 755 "$ROOT_DIR/var/empty"; do
            echo "chmod /var/empty failed"
            sleep 5
            if [ "$COUNTER" -eq "$MAX_RETRIES" ]; then
              echo "chmod failed"
              exit 1
            fi
            COUNTER="$((COUNTER + 1))"
          done
          echo "permissions fix done"
        }

        loadModules
        mountPartition
        fixPermissions
        wipePartition
        umountPartition
      '';
}