1 files changed, 161 insertions, 0 deletions
diff --git a/nixos/modules/services/misc/matrix-appservice-discord.nix b/nixos/modules/services/misc/matrix-appservice-discord.nix
new file mode 100644
index 00000000000..8a8c7f41e3c
--- /dev/null
+++ b/nixos/modules/services/misc/matrix-appservice-discord.nix
@@ -0,0 +1,161 @@
+{ config, options, pkgs, lib, ... }:
+
+with lib;
+
+let
+  dataDir = "/var/lib/matrix-appservice-discord";
+  registrationFile = "${dataDir}/discord-registration.yaml";
+  appDir = "${pkgs.matrix-appservice-discord}/${pkgs.matrix-appservice-discord.passthru.nodeAppDir}";
+  cfg = config.services.matrix-appservice-discord;
+  opt = options.services.matrix-appservice-discord;
+  # TODO: switch to configGen.json once RFC42 is implemented
+  settingsFile = pkgs.writeText "matrix-appservice-discord-settings.json" (builtins.toJSON cfg.settings);
+
+in {
+  options = {
+    services.matrix-appservice-discord = {
+      enable = mkEnableOption "a bridge between Matrix and Discord";
+
+      settings = mkOption rec {
+        # TODO: switch to types.config.json as prescribed by RFC42 once it's implemented
+        type = types.attrs;
+        apply = recursiveUpdate default;
+        default = {
+          database = {
+            filename = "${dataDir}/discord.db";
+          };
+
+          # empty values necessary for registration file generation
+          # actual values defined in environmentFile
+          auth = {
+            clientID = "";
+            botToken = "";
+          };
+        };
+        example = literalExpression ''
+          {
+            bridge = {
+              domain = "public-domain.tld";
+              homeserverUrl = "http://public-domain.tld:8008";
+            };
+          }
+        '';
+        description = ''
+          <filename>config.yaml</filename> configuration as a Nix attribute set.
+          </para>
+
+          <para>
+          Configuration options should match those described in
+          <link xlink:href="https://github.com/Half-Shot/matrix-appservice-discord/blob/master/config/config.sample.yaml">
+          config.sample.yaml</link>.
+          </para>
+
+          <para>
+          <option>config.bridge.domain</option> and <option>config.bridge.homeserverUrl</option>
+          should be set to match the public host name of the Matrix homeserver for webhooks and avatars to work.
+          </para>
+
+          <para>
+          Secret tokens should be specified using <option>environmentFile</option>
+          instead of this world-readable attribute set.
+        '';
+      };
+
+      environmentFile = mkOption {
+        type = types.nullOr types.path;
+        default = null;
+        description = ''
+          File containing environment variables to be passed to the matrix-appservice-discord service,
+          in which secret tokens can be specified securely by defining values for
+          <literal>APPSERVICE_DISCORD_AUTH_CLIENT_I_D</literal> and
+          <literal>APPSERVICE_DISCORD_AUTH_BOT_TOKEN</literal>.
+        '';
+      };
+
+      url = mkOption {
+        type = types.str;
+        default = "http://localhost:${toString cfg.port}";
+        defaultText = literalExpression ''"http://localhost:''${toString config.${opt.port}}"'';
+        description = ''
+          The URL where the application service is listening for HS requests.
+        '';
+      };
+
+      port = mkOption {
+        type = types.port;
+        default = 9005; # from https://github.com/Half-Shot/matrix-appservice-discord/blob/master/package.json#L11
+        description = ''
+          Port number on which the bridge should listen for internal communication with the Matrix homeserver.
+        '';
+      };
+
+      localpart = mkOption {
+        type = with types; nullOr str;
+        default = null;
+        description = ''
+          The user_id localpart to assign to the AS.
+        '';
+      };
+
+      serviceDependencies = mkOption {
+        type = with types; listOf str;
+        default = optional config.services.matrix-synapse.enable "matrix-synapse.service";
+        defaultText = literalExpression ''
+          optional config.services.matrix-synapse.enable "matrix-synapse.service"
+        '';
+        description = ''
+          List of Systemd services to require and wait for when starting the application service,
+          such as the Matrix homeserver if it's running on the same host.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.matrix-appservice-discord = {
+      description = "A bridge between Matrix and Discord.";
+
+      wantedBy = [ "multi-user.target" ];
+      wants = [ "network-online.target" ] ++ cfg.serviceDependencies;
+      after = [ "network-online.target" ] ++ cfg.serviceDependencies;
+
+      preStart = ''
+        if [ ! -f '${registrationFile}' ]; then
+          ${pkgs.matrix-appservice-discord}/bin/matrix-appservice-discord \
+            --generate-registration \
+            --url=${escapeShellArg cfg.url} \
+            ${optionalString (cfg.localpart != null) "--localpart=${escapeShellArg cfg.localpart}"} \
+            --config='${settingsFile}' \
+            --file='${registrationFile}'
+        fi
+      '';
+
+      serviceConfig = {
+        Type = "simple";
+        Restart = "always";
+
+        ProtectSystem = "strict";
+        ProtectHome = true;
+        ProtectKernelTunables = true;
+        ProtectKernelModules = true;
+        ProtectControlGroups = true;
+
+        DynamicUser = true;
+        PrivateTmp = true;
+        WorkingDirectory = appDir;
+        StateDirectory = baseNameOf dataDir;
+        UMask = 0027;
+        EnvironmentFile = cfg.environmentFile;
+
+        ExecStart = ''
+          ${pkgs.matrix-appservice-discord}/bin/matrix-appservice-discord \
+            --file='${registrationFile}' \
+            --config='${settingsFile}' \
+            --port='${toString cfg.port}'
+        '';
+      };
+    };
+  };
+
+  meta.maintainers = with maintainers; [ pacien ];
+}