nixos/duckdns: init module

nixos/modules/module-list.nix

@@ -744,6 +744,7 @@
   ./services/misc/disnix.nix
   ./services/misc/docker-registry.nix
   ./services/misc/domoticz.nix
+  ./services/misc/duckdns.nix
   ./services/misc/duckling.nix
   ./services/misc/dwm-status.nix
   ./services/misc/dysnomia.nix

nixos/modules/services/misc/duckdns.nix

@@ -0,0 +1,97 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  cfg = config.services.duckdns;
+in
+{
+  options.services.duckdns = {
+    enable = lib.mkEnableOption "DuckDNS Dynamic DNS Client";
+    tokenFile = lib.mkOption {
+      default = null;
+      type = lib.types.path;
+      description = ''
+        The path to a file containing the token
+        used to authenticate with DuckDNS.
+      '';
+    };
+
+    domains = lib.mkOption {
+      default = null;
+      type = lib.types.nullOr (lib.types.listOf lib.types.str);
+      example = [ "examplehost" ];
+      description = ''
+        The domain(s) to update in DuckDNS
+        (without the .duckdns.org prefix)
+      '';
+    };
+
+    domainsFile = lib.mkOption {
+      default = null;
+      type = lib.types.nullOr lib.types.path;
+      example = lib.literalExpression ''
+        pkgs.writeText "duckdns-domains.txt" '''
+          examplehost
+          examplehost2
+          examplehost3
+        '''
+      '';
+      description = ''
+        The path to a file containing a
+        newline-separated list of DuckDNS
+        domain(s) to be updated
+        (without the .duckdns.org prefix)
+      '';
+    };
+
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = lib.xor (cfg.domains != null) (cfg.domainsFile != null);
+        message = ''
+          Either services.duckdns.domains or services.duckdns.domainsFile has be defined.
+          Both can't be defined at the same time
+        '';
+      }
+      {
+        assertion = (cfg.tokenFile != null);
+        message = "services.duckdns.tokenFile has to be defined";
+      }
+    ];
+    systemd.services.duckdns = {
+      description = "DuckDNS Dynamic DNS Client";
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      startAt = "*:0/5";
+      path = [
+        pkgs.gnused
+        pkgs.systemd
+        pkgs.curl
+      ];
+      serviceConfig = {
+        Type = "simple";
+        LoadCredential = [
+          "DUCKDNS_TOKEN_FILE:${cfg.tokenFile}"
+        ] ++ lib.optionals (cfg.domainsFile != null) [ "DUCKDNS_DOMAINS_FILE:${cfg.domainsFile}" ];
+        DynamicUser = true;
+      };
+      script = ''
+        export DUCKDNS_TOKEN=$(systemd-creds cat DUCKDNS_TOKEN_FILE)
+        ${lib.optionalString (cfg.domains != null) ''
+          export DUCKDNS_DOMAINS='${lib.strings.concatStringsSep "," cfg.domains}'
+        ''}
+        ${lib.optionalString (cfg.domainsFile != null) ''
+          export DUCKDNS_DOMAINS=$(systemd-creds cat DUCKDNS_DOMAINS_FILE | sed -z 's/\n/,/g')
+        ''}
+        curl --no-progress-meter -k -K- <<< "url = \"https://www.duckdns.org/update?domains=$DUCKDNS_DOMAINS&token=$DUCKDNS_TOKEN&ip=\"" | grep -v "KO"
+      '';
+    };
+  };
+
+  meta.maintainers = with lib.maintainers; [ notthebee ];
+}