feat: add restic hetzner module, script still wip

flake.nix

@@ -160,6 +160,8 @@
         ;
     }
     // flake-utils.lib.eachDefaultSystem (system: rec {
+      apps.setupHetznerStorageBoxes = import ./nix/setup-hetzner-storage-boxes.nix self;
+
       pkgs = import nixpkgs {
         inherit system;
         config.allowUnfree = true;

hosts/sire/fs.nix

@@ -80,6 +80,7 @@ in {
             "rpool/local/state<" = true;
             "rpool/safe<" = true;
             "storage/safe<" = true;
+            "storage/bunker<" = true;
           };
           snapshotting = {
             type = "periodic";

hosts/sire/guests/samba.nix

@@ -209,4 +209,37 @@ in {
     ];
 
   users.groups = lib.mapAttrs (_: cfg: {gid = cfg.id;}) (smbUsers // smbGroups);
+
+  # Backups
+  # ========================================================================
+
+  age.secrets.restic-encryption-password.generator.script = "alnum";
+  age.secrets.restic-ssh-privkey.generator.script = "ssh-ed25519";
+
+  services.restic.backups.main = {
+    hetznerStorageBox = let
+      box = config.repo.secrets.global.hetzner.storageboxes.dusk;
+    in {
+      enable = true;
+      inherit (box) mainUser;
+      inherit (box.users.samba) subUid path;
+      sshPrivateKeyFile = config.age.secrets.restic-ssh-privkey.path;
+    };
+
+    user = "root";
+    timerConfig = {
+      OnCalendar = "06:15";
+      RandomizedDelaySec = "3h";
+      Persistent = true;
+    };
+    initialize = true;
+    passwordFile = config.age.secrets.restic-encryption-password.path;
+    paths = ["/bunker"];
+    pruneOpts = [
+      "--keep-daily 14"
+      "--keep-weekly 7"
+      "--keep-monthly 12"
+      "--keep-yearly 75"
+    ];
+  };
 }

modules/default.nix

@@ -34,6 +34,7 @@
     ./oauth2-proxy.nix
     ./promtail.nix
     ./provided-domains.nix
+    ./restic.nix
     ./secrets.nix
     ./telegraf.nix
     ./wireguard-proxy.nix

modules/restic.nix

@@ -0,0 +1,57 @@
+{lib, ...}: let
+  inherit
+    (lib)
+    mkEnableOption
+    mkIf
+    mkOption
+    types
+    ;
+in {
+  options.services.restic.backups = {
+    type = types.attrsOf (types.submodule ({config}: {
+      options.hetznerStorageBox = {
+        enable = mkEnableOption "Automatically configure this backup to use the given hetzner storage box. Will use SFTP via SSH.";
+
+        mainUser = mkOption {
+          type = types.str;
+          description = ''
+            The main user. While not technically required for restic, we still use it to
+            derive the subuser name and it is required for the automatic setup script
+            that creates the users.
+          '';
+        };
+
+        subUid = mkOption {
+          type = types.int;
+          description = "The id of the subuser that was allocated on the hetzner server for this backup.";
+        };
+
+        path = mkOption {
+          type = types.str;
+          description = ''
+            The remote path to backup into. While not technically required for restic
+            (since the subuser is chrooted on the remote), we'll still use it to set
+            a sane repository and it is required for the automatic setup script that
+            creates the users.
+          '';
+        };
+
+        sshPrivateKeyFile = {
+          type = types.path;
+          description = "The path to the ssh private key to use for uploading backups. Don't use a path from the nix store!";
+        };
+      };
+
+      config = let
+        subUser = "${config.hetznerStorageBox.mainUser}-sub${toString config.hetznerStorageBox.subUid}";
+        url = "${subUser}@${subUser}.your-storagebox.de";
+      in
+        mkIf config.hetznerStorageBox.enable {
+          repository = "sftp://${url}:23${config.hetznerStorageBox.path}";
+          extraOptions = [
+            "sftp.command='ssh -s sftp -p 23 -i ${config.hetznerStorageBox.sshPrivateKeyFile} ${url}'"
+          ];
+        };
+    }));
+  };
+}

nix/setup-hetzner-storage-boxes.nix

@@ -0,0 +1,12 @@
+self: system: let
+  pkgs = self.pkgs.${system};
+in {
+  type = "app";
+  drv = pkgs.writeShellApplication {
+    name = "setup-hetzner-storage-boxes";
+    text = ''
+      set -euo pipefail
+
+    '';
+  };
+}