impermanence

systems/x86_64-linux/earth/default.nix

@@ -6,7 +6,7 @@
   config,
   ...
 }: {
-  imports = [./hardware-configuration.nix];
+  imports = [./hardware-configuration.nix (import ./disko.nix {device = "/dev/nvme0n1";})];
 
   nix.settings = {
     trusted-users = ["zoey"];
@@ -73,6 +73,57 @@
   };
   boot.loader.efi.canTouchEfiVariables = true;
 
+  boot.initrd.postDeviceCommands = lib.mkAfter ''
+    mkdir /btrfs_tmp
+    mount /dev/root_vg/root /btrfs_tmp
+    if [[ -e /btrfs_tmp/root ]]; then
+        mkdir -p /btrfs_tmp/old_roots
+        timestamp=$(date --date="@$(stat -c %Y /btrfs_tmp/root)" "+%Y-%m-%-d_%H:%M:%S")
+        mv /btrfs_tmp/root "/btrfs_tmp/old_roots/$timestamp"
+    fi
+
+    delete_subvolume_recursively() {
+        IFS=$'\n'
+        for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
+            delete_subvolume_recursively "/btrfs_tmp/$i"
+        done
+        btrfs subvolume delete "$1"
+    }
+
+    for i in $(find /btrfs_tmp/old_roots/ -maxdepth 1 -mtime +30); do
+        delete_subvolume_recursively "$i"
+    done
+
+    btrfs subvolume create /btrfs_tmp/root
+    umount /btrfs_tmp
+  '';
+
+  fileSystems."/persist".neededForBoot = true;
+  environment.persistence."/persist/system" = {
+    hideMounts = true;
+    directories = [
+      "/etc/nixos"
+      "/var/log"
+      "/var/lib/bluetooth"
+      "/var/lib/nixos"
+      "/var/lib/systemd/coredump"
+      "/etc/NetworkManager/system-connections"
+      {
+        directory = "/var/lib/colord";
+        user = "colord";
+        group = "colord";
+        mode = "u=rwx,g=rx,o=";
+      }
+    ];
+    files = [
+      "/etc/machine-id"
+      {
+        file = "/var/keys/secret_file";
+        parentDirectory = {mode = "u=rwx,g=,o=";};
+      }
+    ];
+  };
+
   networking.hostName = "earth"; # Define your hostname.
 
   networking.extraHosts = "127.0.0.1 local-cald.io";
@@ -104,6 +155,7 @@
   ];
 
   programs.fish.enable = true;
+  programs.fuse.userAllowOther = true;
   users.users.zoey = {
     isNormalUser = true;
     description = "zoey";

systems/x86_64-linux/earth/disko.nix

@@ -0,0 +1,73 @@
+{device ? throw "Set this to your disk device, e.g. /dev/sda", ...}: {
+  disko.devices = {
+    disk.main = {
+      inherit device;
+      type = "disk";
+      content = {
+        type = "gpt";
+        partitions = {
+          boot = {
+            name = "boot";
+            size = "1M";
+            type = "EF02";
+          };
+          esp = {
+            name = "ESP";
+            size = "500M";
+            type = "EF00";
+            content = {
+              type = "filesystem";
+              format = "vfat";
+              mountpoint = "/boot";
+            };
+          };
+          swap = {
+            size = "4G";
+            content = {
+              type = "swap";
+              resumeDevice = true;
+            };
+          };
+          root = {
+            name = "root";
+            size = "100%";
+            content = {
+              type = "lvm_pv";
+              vg = "root_vg";
+            };
+          };
+        };
+      };
+    };
+    lvm_vg = {
+      root_vg = {
+        type = "lvm_vg";
+        lvs = {
+          root = {
+            size = "100%FREE";
+            content = {
+              type = "btrfs";
+              extraArgs = ["-f"];
+
+              subvolumes = {
+                "/root" = {
+                  mountpoint = "/";
+                };
+
+                "/persist" = {
+                  mountOptions = ["subvol=persist" "noatime"];
+                  mountpoint = "/persist";
+                };
+
+                "/nix" = {
+                  mountOptions = ["subvol=nix" "noatime"];
+                  mountpoint = "/nix";
+                };
+              };
+            };
+          };
+        };
+      };
+    };
+  };
+}