feat(matrix): add appservices with signal config

services/matrix/appservices.nix

@@ -0,0 +1,45 @@
+{ config, pkgs, ... }:
+
+let inherit (config.services.matrix-conduit.settings.global) server_name;
+in {
+  # Mautrix-signal settings
+  services.signald.enable = true;
+  systemd.services.matrix-as-signal = {
+    requires = [ "signald.service" ];
+    after = [ "signald.service" ];
+    path = [
+      pkgs.ffmpeg # voice messages need `ffmpeg`
+    ];
+  };
+
+  services.matrix-appservices = {
+    addRegistrationFiles = false;
+    homeserverDomain = server_name;
+    homeserverURL = "https://matrix.${server_name}";
+    services = {
+      signal = {
+        port = 29184;
+        format = "mautrix-python";
+        package = pkgs.unstable.mautrix-signal;
+        serviceConfig = {
+          StateDirectory = [ "matrix-as-signal" ];
+          SupplementaryGroups = [ "signald" ];
+        };
+        settings.signal = {
+          socket_path = config.services.signald.socketPath;
+          outgoing_attachment_dir = "/var/lib/signald/tmp";
+        };
+        settings.bridge.permissions = {
+          "@felschr:${server_name}" = "admin";
+          "@felschr:matrix.org" = "admin";
+        };
+        settings.bridge.encryption = {
+          allow = true;
+          default = true;
+          key_sharing.allow = true;
+          delete_keys.delete_outdated_inbound = false;
+        };
+      };
+    };
+  };
+}

services/matrix/default.nix

@@ -1,5 +1,5 @@
 { ... }:
 
 {
-  imports = [ ./conduit.nix ./element.nix ];
+  imports = [ ./conduit.nix ./element.nix ./appservices.nix ];
 }