feat: added impermanence to ceres

systems/ceres/config/filesystem.nix

@@ -1,6 +1,7 @@
 {
   flake,
   config,
+  lib,
   ...
 }:
 let
@@ -9,16 +10,82 @@ in
 {
   fileSystems = {
     "/" = {
-      device = "/dev/disk/by-uuid/4b740a8e-8123-4d29-8ec2-132aebb0583d";
-      fsType = "ext4";
+      device = "/dev/disk/by-label/root";
+      fsType = "btrfs";
+      options = [
+        "subvol=@"
+      ];
     };
+
+    "/nix" = {
+      device = "/dev/disk/by-label/root";
+      fsType = "btrfs";
+      options = [
+        "subvol=@nix"
+      ];
+    };
+
+    "/persistent" = {
+      device = "/dev/disk/by-label/root";
+      fsType = "btrfs";
+      neededForBoot = true;
+      options = [
+        "subvol=@persistent"
+      ];
+    };
+
     "/boot" = {
-      device = "/dev/disk/by-uuid/34BA-5602";
+      device = "/dev/disk/by-label/BOOT";
       fsType = "vfat";
     };
+
     "/mnt/storage" = {
-      device = "dev/disk/by-label/storage";
-      fsType = "xfs";
+      device = "/dev/disk/by-label/storage";
+      fsType = "ext4";
+    };
+  };
+
+  boot.initrd.postResumeCommands = lib.mkAfter ''
+    mkdir -p /mnt
+    mount -o subvol=/ /dev/disk/by-label/root /mnt
+
+    if [[ -e /mnt/@ ]]; then
+        mkdir -p /mnt/@old_roots
+        timestamp=$(date --date="@$(stat -c %Y /mnt/@)" "+%Y-%m-%d_%H:%M:%S")
+        mv /mnt/@ "/mnt/@old_roots/$timestamp"
+    fi
+
+    delete_subvolume_recursively() {
+        IFS=$'\n'
+        for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
+            delete_subvolume_recursively "/mnt/$i"
+        done
+        btrfs subvolume delete "$1"
+    }
+
+    for i in $(find /mnt/@old_roots/ -maxdepth 1 -mtime +30); do
+        delete_subvolume_recursively "$i"
+    done
+
+    btrfs subvolume create /mnt/@
+    umount /mnt
+  '';
+
+  environment.persistence."/persistent" = {
+    hideMounts = true;
+    directories = [
+      "/var/log"
+      "/var/lib"
+      "/var/cache"
+      "/etc/ssh"
+    ];
+    files = [
+      "/etc/machine-id"
+    ];
+    users.${user0} = {
+      directories = [
+        ".ssh"
+      ];
     };
   };