From 4cd5a921cfdda41804767daeeebd1999567c31b5 Mon Sep 17 00:00:00 2001
From: Kalle Struik <kalle@kallestruik.nl>
Date: Fri, 22 Nov 2024 18:05:37 +0100
Subject: [PATCH] Impermanence support

---
 flake.lock                                   | 22 ++++++++++--
 flake.nix                                    |  1 +
 systems/{base.nix => base/configuration.nix} | 29 ++++++++++------
 systems/base/fs.nix                          | 36 ++++++++++++++++++++
 utils.nix                                    |  5 ++-
 5 files changed, 78 insertions(+), 15 deletions(-)
 rename systems/{base.nix => base/configuration.nix} (77%)
 create mode 100644 systems/base/fs.nix

diff --git a/flake.lock b/flake.lock
index bf53ed2..b7fee96 100644
--- a/flake.lock
+++ b/flake.lock
@@ -1,12 +1,27 @@
 {
   "nodes": {
+    "impermanence": {
+      "locked": {
+        "lastModified": 1731242966,
+        "narHash": "sha256-B3C3JLbGw0FtLSWCjBxU961gLNv+BOOBC6WvstKLYMw=",
+        "owner": "nix-community",
+        "repo": "impermanence",
+        "rev": "3ed3f0eaae9fcc0a8331e77e9319c8a4abd8a71a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "impermanence",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1731676054,
-        "narHash": "sha256-OZiZ3m8SCMfh3B6bfGC/Bm4x3qc1m2SVEAlkV6iY7Yg=",
+        "lastModified": 1732014248,
+        "narHash": "sha256-y/MEyuJ5oBWrWAic/14LaIr/u5E0wRVzyYsouYY3W6w=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "5e4fbfb6b3de1aa2872b76d49fafc942626e2add",
+        "rev": "23e89b7da85c3640bbc2173fe04f4bd114342367",
         "type": "github"
       },
       "original": {
@@ -18,6 +33,7 @@
     },
     "root": {
       "inputs": {
+        "impermanence": "impermanence",
         "nixpkgs": "nixpkgs"
       }
     }
diff --git a/flake.nix b/flake.nix
index 5bb8033..3fcaed7 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,6 +3,7 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    impermanence.url = "github:nix-community/impermanence";
   };
 
   outputs =
diff --git a/systems/base.nix b/systems/base/configuration.nix
similarity index 77%
rename from systems/base.nix
rename to systems/base/configuration.nix
index 48d203e..453cd8d 100644
--- a/systems/base.nix
+++ b/systems/base/configuration.nix
@@ -5,7 +5,10 @@
   ...
 }:
 {
-  imports = [ (modulesPath + "/profiles/qemu-guest.nix") ];
+  imports = [
+    (modulesPath + "/profiles/qemu-guest.nix")
+    ./fs.nix
+  ];
 
   config = {
     time.timeZone = "Europe/Amsterdam";
@@ -17,10 +20,7 @@
     # Enable QEMU Guest for Proxmox
     services.qemuGuest.enable = lib.mkDefault true;
 
-    # Use the boot drive for grub
-    boot.loader.grub.enable = lib.mkDefault true;
-    boot.loader.grub.devices = [ "/dev/sda" ];
-
+    boot.loader.systemd-boot.enable = true;
     boot.growPartition = lib.mkDefault true;
 
     # Allow remote updates with flakes and non-root users
@@ -45,7 +45,7 @@
 
     # Enable mDNS for `hostname.local` addresses
     services.avahi.enable = true;
-    services.avahi.nssmdns = true;
+    services.avahi.nssmdns4 = true;
     services.avahi.publish = {
       enable = true;
       addresses = true;
@@ -68,11 +68,18 @@
     };
     programs.ssh.startAgent = true;
 
-    # Default filesystem
-    fileSystems."/" = lib.mkDefault {
-      device = "/dev/disk/by-label/nixos";
-      autoResize = true;
-      fsType = "ext4";
+    environment.persistence."/persistent" = {
+      enable = true;
+      hideMounts = true;
+      directories = [
+        "/var/log"
+        "/var/lib/nixos"
+        "/var/lib/systemd/coredump"
+        "/etc/nixos"
+      ];
+      files = [
+        "/etc/machine-id"
+      ];
     };
 
     system.stateVersion = lib.mkDefault "24.05";
diff --git a/systems/base/fs.nix b/systems/base/fs.nix
new file mode 100644
index 0000000..0234440
--- /dev/null
+++ b/systems/base/fs.nix
@@ -0,0 +1,36 @@
+{
+  ...
+}:
+{
+    boot.supportedFilesystems = [ "btrfs" ];
+
+    fileSystems."/" = {
+      device = "none";
+      fsType = "tmpfs";
+      options = [ "default" "mode=755" ];
+    };
+
+    fileSystems."/boot" = {
+      device = "/dev/disk/by-label/boot";
+      fsType = "fat";
+    };
+
+    fileSystems."/nix" = {
+      device = "/dev/disk/by-label/btrfs";
+      fsType = "btrfs";
+      options = [ "compress=zstd" "subvol=nix" "noatime" ];
+    };
+
+    fileSystems."/persistent" = {
+      device = "/dev/disk/by-label/btrfs";
+      fsType = "btrfs";
+      options = [ "compress=zstd" "subvol=persistent" "noatime" ];
+      autoResize = true;
+      neededForBoot = true;
+    };
+
+    fileSystems."/media" = {
+      device = "vm@b9b22d11-3492-49a6-92b7-b36cdf0161fe.cephfs=/media";
+      fsType = "ceph";
+    };
+}
diff --git a/utils.nix b/utils.nix
index 71b6df4..1d821d5 100644
--- a/utils.nix
+++ b/utils.nix
@@ -12,6 +12,9 @@
       specialArgs = {
         inherit inputs outputs;
       };
-      modules = [ ./systems/base.nix ] ++ configs;
+      modules = [ 
+        inputs.impermanence.nixosModules.impermanence
+        ./systems/base/configuration.nix 
+      ] ++ configs;
     };
 }