flake: add nixosModule

flake.nix

@@ -15,6 +15,11 @@
         };
       })
     ];
+
+    nixosModules = rec {
+      default = frontpage;
+      frontpage = import ./nixos;
+    };
   } // (flake-utils.lib.eachDefaultSystem (system:
     let pkgs = import nixpkgs { inherit system; overlays = [ self.overlay ]; }; in
     {

nixos/default.nix

@@ -0,0 +1,76 @@
+{ config, lib, pkgs, ... }:
+with lib;
+let
+  cfg = config.services.frontpage;
+
+  toml = pkgs.formats.toml { };
+  fullSettings = recursiveUpdate cfg.settings {
+    core.port = cfg.port;
+    oidc.client_secret = "@SECRET@";
+  };
+  settingsFile = toml.generate "config.toml" fullSettings;
+in
+{
+  options.services.frontpage = {
+    enable = mkEnableOption "frontpage";
+
+    package = mkPackageOption pkgs "frontpage";
+
+    user = mkOption {
+      type = types.str;
+      default = "frontpage";
+    };
+
+    group = mkOption {
+      type = types.str;
+      default = "frontpage";
+    };
+
+    port = mkOption {
+      type = types.port;
+      default = 32195;
+    };
+
+    oidcSecretFile = mkOption {
+      type = types.path;
+      description = ''
+        Path to a file containing the OIDC secret for the application.
+      '';
+    };
+
+    settings = mkOption {
+      type = with types; attrsOf (oneOf [ str int (listOf str) ]);
+      default = { };
+      description = ''
+        Settings attribute set as described by the documentation.
+      '';
+    };
+  };
+  config = {
+    systemd.services.frontpage = {
+      description = "Web front page";
+      wantedBy = [ "multi-user.target" ];
+      preStart = ''
+        sed \
+          "s=@SECRET@=$(<${cfg.oidcSecretFile})=" \
+          ${settingsFile} \
+          > /run/frontpage/config.toml
+      '';
+
+      serviceConfig = {
+        Restart = "on-failure";
+        RestartSec = "2s";
+        ExecStart = "${cfg.package}/bin/frontpage -c /run/frontpage/config.toml";
+        RuntimeDirectory = [ "frontpage" ];
+        User = cfg.user;
+      };
+    };
+
+    users.users."${cfg.user}" = {
+      isSystemUser = true;
+      group = cfg.group;
+    };
+
+    users.groups."${cfg.group}" = { };
+  };
+}