WIP: add note about 'iwd'

TODO:
* Do home-manager
* Look at for more inspiration github.com:nix-community/impermanence/pull/108
* Common files github.com:nix-community/impermanence/issues/10
* Useful config: github.com:chayleaf/dotfiles/blob/f77271b249e0c08368573c22a5c34f0737d3a766/system/modules/impermanence.nix

flake.lock

@@ -150,6 +150,22 @@
         "type": "github"
       }
     },
+    "impermanence": {
+      "locked": {
+        "lastModified": 1697303681,
+        "narHash": "sha256-caJ0rXeagaih+xTgRduYtYKL1rZ9ylh06CIrt1w5B4g=",
+        "owner": "nix-community",
+        "repo": "impermanence",
+        "rev": "0f317c2e9e56550ce12323eb39302d251618f5b5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "ref": "master",
+        "repo": "impermanence",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1732521221,
@@ -214,6 +230,7 @@
         "flake-parts": "flake-parts",
         "futils": "futils",
         "home-manager": "home-manager",
+        "impermanence": "impermanence",
         "nixpkgs": "nixpkgs",
         "nur": "nur",
         "pre-commit-hooks": "pre-commit-hooks",

flake.nix

@@ -43,6 +43,13 @@
       };
     };
 
+    impermanence = {
+      type = "github";
+      owner = "nix-community";
+      repo = "impermanence";
+      ref = "master";
+    };
+
     nixpkgs = {
       type = "github";
       owner = "NixOS";

modules/nixos/hardware/bluetooth/default.nix

@@ -18,6 +18,13 @@ in
       services.blueman.enable = true;
     }
 
+    # Persist bluetooth files
+    {
+      my.system.persist.directories = [
+        "/var/lib/bluetooth"
+      ];
+    }
+
     # Support for additional bluetooth codecs
     (lib.mkIf cfg.loadExtraCodecs {
       hardware.pulseaudio = {

modules/nixos/hardware/networking/default.nix

@@ -22,6 +22,18 @@ in
   config = lib.mkMerge [
     (lib.mkIf cfg.wireless.enable {
       networking.networkmanager.enable = true;
+
+      # IWD needs persistence if enabled
+
+      # Persist NetworkManager files
+      my.system.persist.files = [
+        "/var/lib/NetworkManager/secret_key"
+        "/var/lib/NetworkManager/seen-bssids"
+        "/var/lib/NetworkManager/timestamps"
+      ];
+      my.system.persist.directories = [
+        "/etc/NetworkManager/system-connections"
+      ];
     })
   ];
 }

modules/nixos/services/aria/default.nix

@@ -69,6 +69,11 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      cfg.downloadDir
+      "/var/lib/aria2"
+    ];
+
     # NOTE: unfortunately aria2 does not log connection failures for fail2ban
   };
 }

modules/nixos/services/audiobookshelf/default.nix

@@ -34,6 +34,10 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      "/var/lib/${config.services.audiobookshelf.dataDir}"
+    ];
+
     services.fail2ban.jails = {
       audiobookshelf = ''
         enabled = true

modules/nixos/services/blog/default.nix

@@ -41,5 +41,12 @@ in
 
     # Those are all subdomains, no problem
     my.services.nginx.virtualHosts = hostsInfo;
+
+    my.system.persist.directories = [
+      "/var/www/blog"
+      "/var/www/cv"
+      "/var/www/dev"
+      "/var/www/key"
+    ];
   };
 }

modules/nixos/services/calibre-web/default.nix

@@ -53,6 +53,11 @@ in
       ];
     };
 
+    my.system.persist.directories = [
+      "/var/lib/${config.services.calibre-web.dataDir}"
+      cfg.libraryPath
+    ];
+
     services.fail2ban.jails = {
       calibre-web = ''
         enabled = true

modules/nixos/services/drone/runner-docker/default.nix

@@ -39,5 +39,7 @@ in
       extraGroups = [ "docker" ]; # Give access to the daemon
     };
     users.groups.drone-runner-docker = { };
+
+    # FIXME: persistence?
   };
 }

modules/nixos/services/drone/runner-exec/default.nix

@@ -63,5 +63,7 @@ in
       group = "drone-runner-exec";
     };
     users.groups.drone-runner-exec = { };
+
+    # FIXME: persistence?
   };
 }

modules/nixos/services/drone/server/default.nix

@@ -50,5 +50,7 @@ in
         inherit (cfg) port;
       };
     };
+
+    # FIXME: persistence?
   };
 }

modules/nixos/services/fail2ban/default.nix

@@ -33,5 +33,9 @@ in
         bantime = "10m";
       };
     };
+
+    my.system.persist.directories = [
+      "/var/lib/fail2ban"
+    ];
   };
 }

modules/nixos/services/flood/default.nix

@@ -28,6 +28,10 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      "/var/lib/flood"
+    ];
+
     # NOTE: unfortunately flood does not log connection failures for fail2ban
   };
 }

modules/nixos/services/forgejo/default.nix

@@ -147,6 +147,11 @@ in
       ];
     };
 
+    my.system.persist.directories = [
+      config.services.forgejo.lfs.contentDir
+      config.services.forgejo.repositoryRoot
+    ];
+
     services.fail2ban.jails = {
       forgejo = ''
         enabled = true

modules/nixos/services/gitea/default.nix

@@ -131,6 +131,11 @@ in
       ];
     };
 
+    my.system.persist.directories = [
+      config.services.gitea.lfs.contentDir
+      config.services.gitea.repositoryRoot
+    ];
+
     services.fail2ban.jails = {
       gitea = ''
         enabled = true

modules/nixos/services/grocy/default.nix

@@ -37,6 +37,16 @@ in
       useACMEHost = config.networking.domain;
     };
 
+    my.services.backup = {
+      paths = [
+        config.services.grocy.dataDir
+      ];
+    };
+
+    my.system.persist.directories = [
+      config.services.grocy.dataDir
+    ];
+
     # NOTE: unfortunately grocy does not log connection failures for fail2ban
   };
 }

modules/nixos/services/indexers/default.nix

@@ -33,6 +33,10 @@ in
           port = jackettPort;
         };
       };
+
+      my.system.persist.directories = [
+        config.services.jackett.dataDir
+      ];
     })
 
     (lib.mkIf cfg.nzbhydra.enable {
@@ -45,6 +49,10 @@ in
           port = nzbhydraPort;
         };
       };
+
+      my.system.persist.directories = [
+        config.services.nzbhydra2.dataDir
+      ];
     })
 
     (lib.mkIf cfg.prowlarr.enable {
@@ -58,6 +66,10 @@ in
         };
       };
 
+      my.system.persist.directories = [
+        "/var/lib/prowlarr"
+      ];
+
       services.fail2ban.jails = {
         prowlarr = ''
           enabled = true

modules/nixos/services/jellyfin/default.nix

@@ -38,6 +38,10 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      "/var/lib/jellyfin"
+    ];
+
     services.fail2ban.jails = {
       jellyfin = ''
         enabled = true

modules/nixos/services/komga/default.nix

@@ -36,6 +36,10 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      config.services.komga.stateDir
+    ];
+
     services.fail2ban.jails = {
       komga = ''
         enabled = true

modules/nixos/services/lohr/default.nix

@@ -107,5 +107,9 @@ in
         };
       };
     };
+
+    my.system.persist.directories = [
+      "/var/lib/lohr"
+    ];
   };
 }

modules/nixos/services/matrix/default.nix

@@ -214,5 +214,9 @@ in
         config.services.matrix-synapse.dataDir
       ];
     };
+
+    my.system.persist.directories = [
+      config.services.matrix-synapse.dataDir
+    ];
   };
 }

modules/nixos/services/mealie/default.nix

@@ -72,6 +72,12 @@ in
       };
     };
 
+    my.services.backup = {
+      paths = [
+        "/var/lib/mealie"
+      ];
+    };
+
     services.fail2ban.jails = {
       mealie = ''
         enabled = true

modules/nixos/services/monitoring/default.nix

@@ -130,5 +130,10 @@ in
         inherit (cfg.grafana) port;
       };
     };
+
+    my.system.persist.directories = [
+      config.services.grafana.dataDir
+      "/var/lib/${config.services.prometheus.stateDir}"
+    ];
   };
 }

modules/nixos/services/navidrome/default.nix

@@ -53,6 +53,10 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      "/var/lib/navidrome"
+    ];
+
     services.fail2ban.jails = {
       navidrome = ''
         enabled = true

modules/nixos/services/nextcloud/collabora.nix

@@ -46,5 +46,7 @@ in
         ];
       };
     };
+
+    # FIXME: persistence?
   };
 }

modules/nixos/services/nextcloud/default.nix

@@ -92,6 +92,10 @@ in
       ];
     };
 
+    my.system.persist.directories = [
+      config.services.nextcloud.home
+    ];
+
     services.fail2ban.jails = {
       nextcloud = ''
         enabled = true

modules/nixos/services/nginx/default.nix

@@ -486,5 +486,9 @@ in
         }
       ];
     };
+
+    my.system.persist.directories = [
+      "/var/lib/acme"
+    ];
   };
 }

modules/nixos/services/paperless/default.nix

@@ -146,5 +146,10 @@ in
         config.services.paperless.mediaDir
       ];
     };
+
+    my.system.persist.directories = [
+      config.services.paperless.dataDir
+      config.services.paperless.mediaDir
+    ];
   };
 }

modules/nixos/services/pdf-edit/default.nix

@@ -54,6 +54,10 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      "/var/lib/stirling-pdf"
+    ];
+
     services.fail2ban.jails = {
       stirling-pdf = ''
         enabled = true

modules/nixos/services/podgrab/default.nix

@@ -51,5 +51,10 @@ in
         inherit (cfg) port;
       };
     };
+
+    my.system.persist.directories = [
+      config.systemd.services.podgrab.environment.CONFIG
+      config.systemd.services.podgrab.environment.DATA
+    ];
   };
 }

modules/nixos/services/postgresql-backup/default.nix

@@ -24,5 +24,9 @@ in
         (config.services.postgresqlBackup.location + "/*.prev.sql.gz")
       ];
     };
+
+    my.system.persist.directories = [
+      config.services.postgresqlBackup.location
+    ];
   };
 }

modules/nixos/services/postgresql/default.nix

@@ -18,6 +18,13 @@ in
       };
     })
 
+    # Only persist directory if the actual service is enabled
+    (lib.mkIf config.services.postgresql.enable {
+      my.system.persist.directories = [
+        config.services.postgresql.dataDir
+      ];
+    })
+
     # Taken from the manual
     (lib.mkIf cfg.upgradeScript {
       environment.systemPackages =

modules/nixos/services/pyload/default.nix

@@ -53,6 +53,11 @@ in
       };
     };
 
+    my.system.persist.directories = [
+      cfg.downloadDirectory
+      "/var/lib/pyload"
+    ];
+
     services.fail2ban.jails = {
       pyload = ''
         enabled = true

modules/nixos/services/quassel/default.nix

@@ -46,5 +46,9 @@ in
       # Because Quassel does not use the socket, I simply trust its connection
       authentication = "host quassel quassel localhost trust";
     };
+
+    my.system.persist.directories = [
+      config.services.quassel.dataDir
+    ];
   };
 }

modules/nixos/services/rss-bridge/default.nix

@@ -22,5 +22,9 @@ in
       forceSSL = true;
       useACMEHost = config.networking.domain;
     };
+
+    my.system.persist.directories = [
+      config.services.rss-bridge.dataDir
+    ];
   };
 }

modules/nixos/services/sabnzbd/default.nix

@@ -24,6 +24,10 @@ in
       };
     };
 
+    my.system.persist.files = [
+      config.services.sabnzbd.configFile
+    ];
+
     services.fail2ban.jails = {
       sabnzbd = ''
         enabled = true

modules/nixos/services/servarr/default.nix

@@ -19,6 +19,16 @@ let
       enable = true;
       group = "media";
     };
+
+    my.system.persist.directories =
+      let
+        # Bazarr breaks the mold unfortunately
+        dataDir =
+          if service != "bazarr"
+          then config.services.${service}.dataDir
+          else "/var/lib/bazarr";
+      in
+      [ dataDir ];
   };
 
   mkRedirection = service: {

modules/nixos/services/ssh-server/default.nix

@@ -20,6 +20,13 @@ in
       };
     };
 
+    # Persist SSH keys
+    my.system.persist.files =
+      let
+        pubAndPrivKey = key: [ key.path "${key.path}.pub" ];
+      in
+      lib.concatMap pubAndPrivKey config.services.openssh.hostKeys;
+
     # Opens the relevant UDP ports.
     programs.mosh.enable = true;
   };

modules/nixos/services/tandoor-recipes/default.nix

@@ -83,6 +83,16 @@ in
       };
     };
 
+    my.services.backup = {
+      paths = [
+        "/var/lib/tandoor-recipes"
+      ];
+    };
+
+    my.system.persist.directories = [
+      "/var/lib/tandoor-recipes"
+    ];
+
     # NOTE: unfortunately tandoor-recipes does not log connection failures for fail2ban
   };
 }

modules/nixos/services/transmission/default.nix

@@ -91,6 +91,11 @@ in
       allowedUDPPorts = [ cfg.peerPort ];
     };
 
+    my.system.persist.directories = [
+      cfg.downloadBase
+      config.services.transmission.home
+    ];
+
     # NOTE: unfortunately transmission does not log connection failures for fail2ban
   };
 }

modules/nixos/services/vikunja/default.nix

@@ -100,6 +100,10 @@ in
       ];
     };
 
+    my.system.persist.directories = [
+      config.services.vikunja.settings.files.basepath
+    ];
+
     # NOTE: unfortunately vikunja does not log connection failures for fail2ban
   };
 }

modules/nixos/services/woodpecker/agent-docker/default.nix

@@ -38,5 +38,7 @@ in
         ];
       };
     };
+
+    # FIXME: persistence?
   };
 }

modules/nixos/services/woodpecker/agent-exec/default.nix

@@ -62,5 +62,7 @@ in
         ];
       };
     };
+
+    # FIXME: persistence?
   };
 }

modules/nixos/services/woodpecker/server/default.nix

@@ -61,5 +61,7 @@ in
         port = cfg.rpcPort;
       };
     };
+
+    # FIXME: persistence
   };
 }

modules/nixos/system/default.nix

@@ -9,6 +9,7 @@
     ./language
     ./nix
     ./packages
+    ./persist
     ./podman
     ./polkit
     ./printing

modules/nixos/system/docker/default.nix

@@ -23,5 +23,9 @@ in
         ];
       };
     };
+
+    my.system.persist.directories = [
+      "/var/lib/docker"
+    ];
   };
 }

modules/nixos/system/persist/default.nix

@@ -0,0 +1,70 @@
+# Ephemeral root configuration
+{ config, inputs, lib, ... }:
+let
+  cfg = config.my.system.persist;
+in
+{
+  imports = [
+    inputs.impermanence.nixosModules.impermanence
+  ];
+
+  options.my.system.persist = with lib; {
+    enable = mkEnableOption "stateless system configuration";
+
+    mountPoint = lib.mkOption {
+      type = types.str;
+      default = "/persistent";
+      example = "/etc/nix/persist";
+      description = ''
+        Which mount point should be used to persist this system's files and
+        directories.
+      '';
+    };
+
+    files = lib.mkOption {
+      type = with types; listOf str;
+      default = [ ];
+      example = [
+        "/etc/nix/id_rsa"
+      ];
+      description = ''
+        Additional files in the root to link to persistent storage.
+      '';
+    };
+
+    directories = lib.mkOption {
+      type = with types; listOf str;
+      default = [ ];
+      example = [
+        "/var/lib/libvirt"
+      ];
+      description = ''
+        Additional directories in the root to link to persistent storage.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    environment.persistence."${cfg.mountPoint}" = {
+      files = [
+        "/etc/machine-id" # Machine-specific ID
+        "/etc/adjtime" # Clock drift factor and offsets
+      ]
+      ++ lib.unique cfg.files
+      ;
+
+      directories = [
+        "/etc/nixos" # In case it's storage directory of our configuration
+        "/var/log" # Logs
+        "/var/lib/nixos" # UID/GID maps
+        "/var/lib/systemd/coredump" # Coredumps
+
+        "/var/lib/systemd" # FIXME: needed?
+        "/var/spool" # FIXME: needed?
+        "/var/tmp" # FIXME: needed?
+      ]
+      ++ lib.unique cfg.directories
+      ;
+    };
+  };
+}

modules/nixos/system/podman/default.nix

@@ -44,5 +44,9 @@ in
         ];
       };
     };
+
+    my.system.persist.directories = [
+      "/var/lib/containers"
+    ];
   };
 }

modules/nixos/system/printing/default.nix

@@ -65,5 +65,7 @@ in
       # Allow resolution of '.local' addresses
       nssmdns4 = true;
     };
+
+    # FIXME: persistence?
   };
 }