feat(rsync-backup): fix rsync backup quirks and rsyncd port bug

Still dont know what is using port 873 on shan...
Rsync backup testing continues

hosts/brontes/configuration.nix

@@ -46,7 +46,11 @@
           "/home/ny/Downloads"
           "/home/ny/notes"
         ];
-        target = "/home/ny/test";
+        target = {
+          location = "backup";
+          type = "rsyncd";
+          host = "shan";
+        };
         incremental.enable = true;
       };
     };

hosts/raptus/headscale.nix

@@ -121,6 +121,15 @@ mkIf config.services.headscale.enable {
       acls = [
         (mkAcl [ "tag:client" ] [ "tag:client:*" ]) # client -> client
         (mkAcl [ "tag:client" ] [ "tag:server:*" ]) # client -> server
+        {
+          action = "accept";
+          src = [
+            "tag:client"
+            "tag:server"
+          ];
+          proto = "rsync"; # optional
+          dst = [ "tag:backup" ];
+        }
       ];
 
       ssh = [
@@ -133,6 +142,7 @@ mkIf config.services.headscale.enable {
       tags = [
         "tag:client"
         "tag:server"
+        "tag:backup"
       ];
 
       tagOwners =

hosts/shan/configuration.nix

@@ -68,6 +68,24 @@
       isExitNode = true;
       tags = [ "server" ];
     };
+
+    services.rsyncd = {
+      enable = true;
+      port = 9523;
+      settings = {
+        globalSection = {
+          address = "100.64.0.4";
+        };
+        sections = {
+          backup = {
+            path = "/var/backups/test";
+            comment = "ftp export area";
+            "write only" = true;
+            "read only" = false;
+          };
+        };
+      };
+    };
   };
 
   services = {
@@ -78,8 +96,11 @@
       openFirewall = true;
       host = "0.0.0.0";
     };
+
   };
 
+  networking.firewall.allowedTCPPorts = [ 9523 ];
+
   environment.systemPackages = map lib.lowPrio [
     pkgs.curl
   ];

options/default.nix

@@ -6,5 +6,7 @@
     ./system
     ./container
     ./server
+
+    ./fixes
   ];
 }

options/fixes/default.nix

@@ -0,0 +1 @@
+{ imports = [ ./rsyncd.nix ]; }

options/fixes/rsyncd.nix

@@ -0,0 +1,134 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  cfg = config.modules.services.rsyncd;
+  settingsFormat = pkgs.formats.iniWithGlobalSection { };
+  configFile = settingsFormat.generate "rsyncd.conf" cfg.settings;
+in
+{
+  options.modules.services.rsyncd = {
+
+    enable = lib.mkEnableOption "the rsync daemon";
+
+    port = lib.mkOption {
+      default = 873;
+      type = lib.types.port;
+      description = "TCP port the daemon will listen on.";
+    };
+
+    settings = lib.mkOption {
+      type = lib.types.oneOf [
+        settingsFormat.type
+        (pkgs.formats.ini { }).type # Retrocompatibility
+      ];
+      default = { };
+      example = {
+        globalSection = {
+          uid = "nobody";
+          gid = "nobody";
+          "use chroot" = true;
+          "max connections" = 4;
+        };
+        sections = {
+          ftp = {
+            path = "/var/ftp/./pub";
+            comment = "whole ftp area";
+          };
+          cvs = {
+            path = "/data/cvs";
+            comment = "CVS repository (requires authentication)";
+            "auth users" = [
+              "tridge"
+              "susan"
+            ];
+            "secrets file" = "/etc/rsyncd.secrets";
+          };
+        };
+      };
+      description = ''
+        Configuration for rsyncd. See
+        {manpage}`rsyncd.conf(5)`.
+      '';
+      apply =
+        val:
+        if (lib.typeOf val == "ini") then
+          {
+            sections = lib.removeAttrs val [ "global" ];
+            globalSection = lib.mkIf (lib.hasAttrs "global") val.global;
+
+          }
+        else
+          val;
+    };
+
+    socketActivated = lib.mkOption {
+      default = false;
+      type = lib.types.bool;
+      description = "If enabled Rsync will be socket-activated rather than run persistently.";
+    };
+
+  };
+
+  config = lib.mkIf cfg.enable {
+
+    modules.services.rsyncd.settings.globalSection.port = toString cfg.port;
+
+    systemd =
+      let
+        serviceConfigSecurity = {
+          ProtectSystem = "full";
+          PrivateDevices = "on";
+          NoNewPrivileges = "on";
+        };
+      in
+      {
+        services.rsync = lib.mkForce {
+          enable = !cfg.socketActivated;
+          aliases = [ "rsyncd.service" ];
+
+          description = "fast remote file copy program daemon";
+          after = [ "network.target" ];
+          documentation = [
+            "man:rsync(1)"
+            "man:rsyncd.conf(5)"
+          ];
+
+          serviceConfig = serviceConfigSecurity // {
+            ExecStart = "${pkgs.rsync}/bin/rsync --daemon --no-detach --config=${configFile}";
+            RestartSec = 1;
+          };
+
+          wantedBy = [ "multi-user.target" ];
+        };
+
+        services."rsync@" = lib.mkForce {
+          description = "fast remote file copy program daemon";
+          after = [ "network.target" ];
+
+          serviceConfig = serviceConfigSecurity // {
+            ExecStart = "${pkgs.rsync}/bin/rsync --daemon --config=${configFile}";
+            StandardInput = "socket";
+            StandardOutput = "inherit";
+            StandardError = "journal";
+          };
+        };
+
+        sockets.rsync = lib.mkForce {
+          enable = cfg.socketActivated;
+
+          description = "socket for fast remote file copy program daemon";
+          conflicts = [ "rsync.service" ];
+
+          listenStreams = [ (toString cfg.port) ];
+          socketConfig.Accept = true;
+
+          wantedBy = [ "sockets.target" ];
+        };
+      };
+
+  };
+}

options/services/rsync/default.nix

@@ -9,8 +9,6 @@ let
     mkIf
     mkEnableOption
     mkOption
-    stringToCharacters
-    head
     concatStringsSep
     ;
   inherit (lib.types)
@@ -19,6 +17,7 @@ let
     package
     enum
     str
+    port
     ;
   cfg = config.modules.services.rsync-backup;
 in
@@ -32,9 +31,10 @@ in
   # - [ ] support
   #       - [ ] nfs
   #       - [ ] sftp
-  #       - [x] ssh
+  #       - [ ] ssh
   #       - [x] local
-  # - retention limit for incremental backups
+  #       - [x] rsyncd
+  # - [ ] retention limit for incremental backups
 
   options.modules.services.rsync-backup = {
     enable = mkEnableOption "rsync backups";
@@ -42,7 +42,6 @@ in
     sources = mkOption {
       type = listOf nonEmptyStr;
       default = [ ]; # TODO: validate if at least 1 element
-      apply = map (s: "\"${s}\"");
       description = ''
         A list of absolute paths to the files or folders that should get synchronized.
         It isn't necessary to wrap them in escaped double quotation marks.
@@ -54,24 +53,42 @@ in
       default = "";
     };
 
-    target = mkOption {
-      type = nonEmptyStr;
-      description = ''
-        The target to where the data should be backed up.
-        If it is a directory, it will be created automatically by rsync.
-        Append a : to the string if it is an ssh target and ensure that passwordless access is available.
-      '';
-    };
+    target = {
+      location = mkOption {
+        type = nonEmptyStr;
+        description = ''
+          The target to where the data should be backed up.
+          If it is a directory, it will be created automatically by rsync.
+          Append a : to the string if it is an ssh target and ensure that passwordless access is available.
+        '';
+      };
 
-    targetType = mkOption {
-      type = enum [
-        "local"
-        "ssh"
-      ];
-      default = if head (stringToCharacters cfg.target) == "/" then "local" else "ssh";
-      description = ''
-        Guesses if the given target is local or ssh, very rudimentary therefore it might be necessary to specify manually (or rewrite the logic).
-      '';
+      finalLocation = mkOption {
+        type = nonEmptyStr;
+        default =
+          if cfg.target.type == "local" then
+            cfg.target.location
+          else if cfg.target.type == "rsyncd" then
+            "rsync://${cfg.target.host}/${cfg.target.location}"
+          else
+            throw "Unable to create location.";
+      };
+
+      type = mkOption {
+        type = enum [
+          "local"
+          "rsyncd"
+        ];
+        default = "local";
+        description = ''
+          Guesses if the given target is local or ssh, very rudimentary therefore it might be necessary to specify manually (or rewrite the logic).
+        '';
+      };
+
+      host = mkOption {
+        type = str;
+        default = "";
+      };
     };
 
     package = mkOption {
@@ -87,6 +104,7 @@ in
       default = [
         "--archive"
         "--verbose"
+        "--mkpath"
       ];
     };
 
@@ -96,13 +114,14 @@ in
         (mkIf cfg.incremental.enable "--delete")
         (mkIf (cfg.exclude != "") "--exclude=\"${cfg.exclude}\"")
         (mkIf cfg.incremental.enable "--backup-dir=\"${cfg.incremental.finalIncrementPath}\"")
+        "--port=${toString cfg.port}"
       ];
       apply = concatStringsSep " ";
     };
 
     interval = mkOption {
       type = nonEmptyStr;
-      default = "1d";
+      default = "daily";
     };
 
     incremental = {
@@ -117,7 +136,15 @@ in
       };
       finalIncrementPath = mkOption {
         type = nonEmptyStr;
-        default = "${cfg.target}/increment/$(date +${cfg.incremental.format})/";
+        default = "../${cfg.target.location}/increment/$(date +${cfg.incremental.format})/";
+        description = ''
+          The directory in which the changes will be stored, the .. at the start is necessary because it is relative to
+          the target and we append `backup` to the target.
+
+          -- cfg.location
+              | - backup/
+              | - increment/<increment format>
+        '';
       };
       # TODO: add retention
     };
@@ -126,34 +153,54 @@ in
       type = nonEmptyStr;
       default = "rsync-backup";
     };
+
+    user = mkOption {
+      type = str;
+      default = "rsync-backup";
+      description = "User account under which Rsync runs.";
+    };
+
+    group = mkOption {
+      type = str;
+      default = "rsync-backup";
+      description = "Group under which Rsync runs.";
+    };
+
+    port = mkOption {
+      type = port;
+      default = 9523;
+    };
   };
 
   config = mkIf cfg.enable {
-
     systemd.timers.${cfg.unitName} = {
       enable = true;
+      wantedBy = [ "timers.target" ];
       unitConfig = {
         Description = "Triggers rsync-backup regularly.";
       };
       timerConfig = {
         Unit = "${cfg.unitName}.service";
-        OnBootSec = cfg.interval;
+        OnCalendar = cfg.interval;
+        Persistent = true;
       };
     };
 
     systemd.services.${cfg.unitName} = {
       script =
         let
-          destination = if cfg.incremental.enable then "${cfg.target}/backup" else cfg.target;
+          destination =
+            if cfg.incremental.enable then "${cfg.target.finalLocation}/backup" else cfg.target.finalLocation;
+          sources = concatStringsSep " " (map (s: "\"${s}\"") cfg.sources);
         in
         ''
           ${cfg.package}/bin/rsync \
               ${cfg.flagsFinal} \
-              ${concatStringsSep " " cfg.sources} \
+              ${sources} \
               "${destination}"
         '';
 
-      requires = mkIf (cfg.targetType == "ssh") [ "network.target" ];
+      requires = mkIf (cfg.target.type == "rsyncd") [ "network.target" ];
       unitConfig = {
         Description = "Backs up files from a source location to a specified destination.";
       };
@@ -161,7 +208,24 @@ in
         Type = "simple";
         Restart = "on-failure";
         RestartSec = 300;
+        PrivateDevices = true;
+        PrivateTmp = true;
+        ProtectSystem = "full";
+        ReadOnlyPaths = concatStringsSep " " cfg.sources;
+        IPAddressAllow = "any";
       };
     };
+
+    users.users = mkIf (cfg.user == "rsync-backup") {
+      rsync-backup = {
+        useDefaultShell = true;
+        group = cfg.group;
+        isSystemUser = true;
+      };
+    };
+
+    users.groups = mkIf (cfg.group == "rsync-backup") {
+      rsync-backup = { };
+    };
   };
 }