From 88f6014fc4a403f0f2c9b40e37d3b114c4972882 Mon Sep 17 00:00:00 2001
From: Dennis Frieberg <dennis@frieberg.de>
Date: Thu, 28 Sep 2023 17:12:34 +0200
Subject: [PATCH] [#9] first impermanence config support

---
 flake.lock                     | 16 +++++++++++++
 flake.nix                      |  3 +++
 nixos/flake-module.nix         |  1 +
 nixos/modules/impermanence.nix | 42 ++++++++++++++++++++++++++++++++++
 nixos/roles/default.nix        | 30 +++++++++++++++++++++++-
 5 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100644 nixos/modules/impermanence.nix

diff --git a/flake.lock b/flake.lock
index e3f7e40..8cc319d 100644
--- a/flake.lock
+++ b/flake.lock
@@ -33,6 +33,21 @@
         "type": "indirect"
       }
     },
+    "impermanence": {
+      "locked": {
+        "lastModified": 1694622745,
+        "narHash": "sha256-z397+eDhKx9c2qNafL1xv75lC0Q4nOaFlhaU1TINqb8=",
+        "owner": "nix-community",
+        "repo": "impermanence",
+        "rev": "e9643d08d0d193a2e074a19d4d90c67a874d932e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "impermanence",
+        "type": "github"
+      }
+    },
     "nixos-mailserver": {
       "inputs": {
         "blobs": "blobs",
@@ -123,6 +138,7 @@
     "root": {
       "inputs": {
         "flake-parts": "flake-parts",
+        "impermanence": "impermanence",
         "nixos-mailserver": "nixos-mailserver",
         "nixpkgs": "nixpkgs",
         "sops-nix": "sops-nix"
diff --git a/flake.nix b/flake.nix
index 727dd91..0c61327 100644
--- a/flake.nix
+++ b/flake.nix
@@ -14,6 +14,9 @@
       url = "github:Mic92/sops-nix";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    impermanence = {
+      url = "github:nix-community/impermanence";
+    };
   };
 
   outputs = inputs@{ flake-parts, ... }:
diff --git a/nixos/flake-module.nix b/nixos/flake-module.nix
index ef87e41..8c44964 100644
--- a/nixos/flake-module.nix
+++ b/nixos/flake-module.nix
@@ -12,6 +12,7 @@
           imports = [
             (import (./. + "/machines/${name}/configuration.nix") inputs)
             inputs.sops-nix.nixosModules.sops
+            inputs.impermanence.nixosModules.impermanence
           ];
         };
     in lib.genAttrs machines makeSystem);
diff --git a/nixos/modules/impermanence.nix b/nixos/modules/impermanence.nix
new file mode 100644
index 0000000..0f955fd
--- /dev/null
+++ b/nixos/modules/impermanence.nix
@@ -0,0 +1,42 @@
+{lib, config, ...} :
+
+let 
+  inherit (lib)
+    mkEnableOption
+    mkIf
+    mkOption
+    types
+    ;
+  cfg = config.impermanence;
+in
+
+{
+imports = [ ];
+
+options.impermanence = {
+  enable = mkEnableOption "impermanence";
+  storagePath = mkOption {
+    type = types.path;
+    default = "/persist/persist";
+    description = "The path where persistent data is stored";
+  };
+  name = mkOption {
+    type = types.str;
+    default = "persist";
+    description = "the name of the persistent data store";
+  };
+};
+
+config = mkIf cfg.enable {
+  environment.persistence.${cfg.name} = {
+    persistentStoragePath = cfg.storagePath;
+    directories = [
+      "/var/log"
+      "/etc/ssh"
+      "/var/lib/nixos"
+    ];
+  };
+  environment.etc.machine-id.source = "${cfg.storagePath}/machine-id";
+};
+
+}
diff --git a/nixos/roles/default.nix b/nixos/roles/default.nix
index 3c24242..adf1200 100644
--- a/nixos/roles/default.nix
+++ b/nixos/roles/default.nix
@@ -1,4 +1,32 @@
-{ ... } : {
+{pkgs, config, lib, ...} : {
+
+imports = [
+  ./admins.nix
+  ./nix_keys.nix
+  ../modules/impermanence.nix
+  ];
+nix = {
+  extraOptions = ''
+    experimental-features = nix-command flakes
+    builders-use-substitutes = true
+  '';
+};
+
+networking = {
+  firewall = { # these shoud be default, but better make sure!
+    enable = true;
+    allowPing = true;
+  };
+  nftables.enable = true;
+  useDHCP = false; # We don't speak DHCP and even if we would, we should enable it per interface
+  # hosts = # TODO write something to autogenerate ip adresses!
+};
+
+users = {
+  mutableUsers = false;
+};
+
+impermanence.enable = true;
 
 sops.age.sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];
 }