Implement aria2 service for controlling a daemon via rpc.

nixos/modules/misc/ids.nix

@@ -289,7 +289,8 @@
       rpc = 271;
       geoip = 272;
       fcron = 273;
-
+      aria2 = 274;
+	  
       # When adding a uid, make sure it doesn't match an existing gid. And don't use uids above 399!
 
       nixbld = 30000; # start of range of uids
@@ -547,6 +548,7 @@
       #rpc = 271; # unused
       #geoip = 272; # unused
       fcron = 273;
+	  aria2 = 274;
 
       # When adding a gid, make sure it doesn't match an existing
       # uid. Users and groups with the same name should have equal

nixos/modules/services/networking/aria2.nix

@@ -0,0 +1,137 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.aria2;
+
+  homeDir = "/var/lib/aria2";
+
+  settingsDir = "${homeDir}";
+  sessionFile = "${homeDir}/aria2.session";
+  downloadDir = "${homeDir}/Downloads";
+  
+  rangesToStringList = map (x: builtins.toString x.from +"-"+ builtins.toString x.to);
+  
+  settingsFile = pkgs.writeText "aria2.conf"
+  ''
+    dir=${cfg.downloadDir}
+    listen-port=${concatStringsSep "," (rangesToStringList cfg.listenPortRange)}
+    rpc-listen-port=${toString cfg.rpcListenPort}
+    rpc-secret=${cfg.rpcSecret}
+  '';
+
+in
+{
+  options = {
+    services.aria2 = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether or not to enable the headless Aria2 daemon service.
+
+          Aria2 daemon can be controlled via the RPC interface using
+          one of many WebUI (http://localhost:6800/ by default).
+
+          Targets are downloaded to ${downloadDir} by default and are
+          accessible to users in the "aria2" group.
+          '';
+      };
+      openPorts = mkOption {
+        type = types.bool;
+        default = true;
+        description = ''
+          Open the ports in the firewall. Defaults are:
+          - UDP 6881-6999 for transfers
+          - TCP 6800 for RPC
+          '';
+      };
+      downloadDir = mkOption {
+        type = types.string;
+        default = "${downloadDir}";
+        description = ''
+          Directory to store downloaded files.
+          '';
+      };
+      listenPortRange = mkOption {
+        type = types.listOf types.attrs;
+        default = [ { from = 6881; to = 6999; } ];
+        description = ''
+          Set UDP listening port range used by DHT(IPv4, IPv6) and UDP tracker.
+          '';
+      };
+      rpcListenPort = mkOption {
+        type = types.int;
+        default = 6800;
+        description = "Specify a port number for JSON-RPC/XML-RPC server to listen to. Possible Values: 1024-65535";
+      };
+      rpcSecret = mkOption {
+        type = types.string;
+        default = "aria2rpc";
+        description = ''
+          Set RPC secret authorization token.
+          Read https://aria2.github.io/manual/en/html/aria2c.html#rpc-auth to know how this option value is used.
+          '';
+      };
+      extraArguments = mkOption {
+        type = types.string;
+        example = "--rpc-secret=12345 --enable-rpc --rpc-listen-all";
+        default = "";
+        description = ''
+          Additional arguments to be passed to Aria2.
+          '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    
+    # Need to open ports for proper functioning
+    networking.firewall = mkIf cfg.openPorts {
+      allowedUDPPortRanges = config.services.aria2.listenPortRange;
+      allowedTCPPorts = [ config.services.aria2.rpcListenPort ];
+    };
+
+    users.extraUsers.aria2 = {
+      group = "aria2";
+      uid = config.ids.uids.aria2;
+      description = "aria2 user";
+      home = homeDir;
+      createHome = false;
+    };
+
+    users.extraGroups.aria2.gid = config.ids.gids.aria2;
+
+    systemd.services.aria2 = {
+      description = "aria2 Service";
+      after = [ "local-fs.target" "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      preStart = ''
+        mkdir -m 0770 -p "${homeDir}"
+				chown aria2:aria2 "${homeDir}"
+        if [[ ! -d "${config.services.aria2.downloadDir}" ]]
+				then 
+					mkdir -m 0770 -p "${config.services.aria2.downloadDir}"
+					chown aria2:aria2 "${config.services.aria2.downloadDir}"
+				fi
+        if [[ ! -e "${sessionFile}" ]]
+				then 
+					touch "${sessionFile}"
+					chown aria2:aria2 "${sessionFile}"
+				fi
+        cp -f "${settingsFile}" "${settingsDir}/aria2.conf"
+      '';
+
+      serviceConfig = {
+        Restart = "on-abort";
+        ExecStart = "${pkgs.aria2}/bin/aria2c --enable-rpc --conf-path=${settingsDir}/aria2.conf ${config.services.aria2.extraArguments} --save-session=${sessionFile}";
+        ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
+        User = "aria2";
+        Group = "aria2";
+				PermissionsStartOnly = true;
+      };
+    };
+  };
+}
+