sys: implement primitive impermanence

3 files changed, 63 insertions, 45 deletions

diff --git a/flake.nix b/flake.nix
index d0357ed..5780813 100644
--- a/flake.nix
+++ b/flake.nix
@@ -9,55 +9,58 @@
     };
 
     nur.url = "github:nix-community/NUR";
+    impermanence.url = "github:nix-community/impermanence";
   };
 
-  outputs = { self, nixpkgs, nixpkgsUnstable, home-manager, nur, ... }: with nixpkgs.lib; let
-    util = import ./util;
-    inherit (util nixpkgs.lib) importAll;
+  outputs =
+    { self, nixpkgs, nixpkgsUnstable, home-manager, nur, impermanence, ... }:
+    with nixpkgs.lib; let
+      util = import ./util;
+      inherit (util nixpkgs.lib) importAll;
 
-    pkgSet = pkgs: import ./pkgs {
-      inherit pkgs;
-      util = util pkgs.lib;
-    };
-  in {
-    packages."x86_64-linux" = pkgSet nixpkgs.legacyPackages."x86_64-linux";
-
-    overlay = self: super: {
-      local = pkgSet super;
-      unstable = import nixpkgsUnstable { inherit (super) config system; };
-    };
+      pkgSet = pkgs: import ./pkgs {
+        inherit pkgs;
+        util = util pkgs.lib;
+      };
+    in {
+      packages."x86_64-linux" = pkgSet nixpkgs.legacyPackages."x86_64-linux";
 
-    nixosConfigurations = let
-      hostConfig = host: (makeOverridable nixosSystem) {
-        system = "x86_64-linux";
-        modules = [ (import ./sys { inherit self; }) host ];
+      overlay = self: super: {
+        local = pkgSet super;
+        unstable = import nixpkgsUnstable { inherit (super) config system; };
       };
-    in mapAttrs (_: hostConfig) (importAll { root = ./sys/platform; });
 
-    homeConfigurations = let
-      home = platform: home-manager.lib.homeManagerConfiguration {
-        system = "x86_64-linux";
+      nixosConfigurations = let
+        hostConfig = host: (makeOverridable nixosSystem) {
+          system = "x86_64-linux";
+          modules = [ (import ./sys { inherit self impermanence; }) host ];
+        };
+      in mapAttrs (_: hostConfig) (importAll { root = ./sys/platform; });
 
-        configuration = import ./home { inherit self nixpkgs nixpkgsUnstable nur; };
-        extraModules = [ platform ];
+      homeConfigurations = let
+        home = platform: home-manager.lib.homeManagerConfiguration {
+          system = "x86_64-linux";
 
-        username = "ale";
-        homeDirectory = "/home/ale";
+          configuration = import ./home { inherit self nixpkgs nixpkgsUnstable nur; };
+          extraModules = [ platform ];
 
-        # Update the state version as needed.
-        # See the changelog here:
-        # https://nix-community.github.io/home-manager/release-notes.html#sec-release-21.05
-        stateVersion = "21.11";
+          username = "ale";
+          homeDirectory = "/home/ale";
 
-        # Optionally use extraSpecialArgs
-        # to pass through arguments to home.nix
-        extraSpecialArgs = {};
-      };
+          # Update the state version as needed.
+          # See the changelog here:
+          # https://nix-community.github.io/home-manager/release-notes.html#sec-release-21.05
+          stateVersion = "21.11";
 
-      homeConfig = id: platform: {
-        name = "ale@${id}";
-        value = home platform;
-      };
-    in mapAttrs' homeConfig (importAll { root = ./home/platform; });
-  };
+          # Optionally use extraSpecialArgs
+          # to pass through arguments to home.nix
+          extraSpecialArgs = {};
+        };
+
+        homeConfig = id: platform: {
+          name = "ale@${id}";
+          value = home platform;
+        };
+      in mapAttrs' homeConfig (importAll { root = ./home/platform; });
+    };
 }
diff --git a/sys/default.nix b/sys/default.nix
index 215361e..ad99009 100644
--- a/sys/default.nix
+++ b/sys/default.nix
@@ -1,8 +1,10 @@
-{ self }:
+{ self, impermanence }:
 { lib, config, pkgs, modulesPath, ... }:
 {
   imports = [
     "${modulesPath}/installer/scan/not-detected.nix"
+    impermanence.nixosModule
+
     ./auth.nix
     ./boot.nix
     ./fs
diff --git a/sys/fs/default.nix b/sys/fs/default.nix
index 9f2f646..d24e357 100644
--- a/sys/fs/default.nix
+++ b/sys/fs/default.nix
@@ -1,19 +1,32 @@
 { lib, config, ... }:
 with lib; let
-  cfg = config.local;
+  cfg = config.local.fs;
 in {
   imports = [ ./btrfs.nix ./layout.nix ];
 
-  options.local.fs.boot.device = with lib.types; mkOption {
-    type = str;
+  options.local.fs = with lib.types; {
+    impermanence = mkOption {
+      type = bool;
+      default = false;
+    };
+
+    boot.device = mkOption {
+      type = str;
+    };
   };
 
   config = {
     # !!!
     boot.tmpOnTmpfs = true;
 
+    fileSystems."/" = mkIf cfg.impermanence {
+      device = "tmpfs";
+      fsType = "tmpfs";
+      options = [ "size=1G" "mode=755" ];
+    };
+
     fileSystems."/boot" = {
-      inherit (cfg.fs.boot) device;
+      inherit (cfg.boot) device;
       fsType = "vfat";
       options = [ "noatime" "umask=027" ];
     };