matrix-synapse service: add plugins option

nixos/modules/services/misc/matrix-synapse.nix

@@ -9,6 +9,9 @@ let
   logConfigFile = pkgs.writeText "log_config.yaml" cfg.logConfig;
   mkResource = r: ''{names: ${builtins.toJSON r.names}, compress: ${boolToString r.compress}}'';
   mkListener = l: ''{port: ${toString l.port}, bind_address: "${l.bind_address}", type: ${l.type}, tls: ${boolToString l.tls}, x_forwarded: ${boolToString l.x_forwarded}, resources: [${concatStringsSep "," (map mkResource l.resources)}]}'';
+  pluginsEnv = cfg.package.python.buildEnv.override {
+    extraLibs = cfg.plugins;
+  };
   configFile = pkgs.writeText "homeserver.yaml" ''
 ${optionalString (cfg.tls_certificate_path != null) ''
 tls_certificate_path: "${cfg.tls_certificate_path}"
@@ -125,6 +128,14 @@ in {
           Overridable attribute of the matrix synapse server package to use.
         '';
       };
+      plugins = mkOption {
+        type = types.listOf types.package;
+        default = [ ];
+        defaultText = "with config.services.matrix-synapse.package.plugins [ matrix-synapse-ldap3 matrix-synapse-pam ]";
+        description = ''
+          List of additional Matrix plugins to make available.
+        '';
+      };
       no_tls = mkOption {
         type = types.bool;
         default = false;
@@ -686,6 +697,7 @@ in {
           --keys-directory ${cfg.dataDir} \
           --generate-keys
       '';
+      environment.PYTHONPATH = makeSearchPathOutput "lib" cfg.package.python.sitePackages [ pluginsEnv ];
       serviceConfig = {
         Type = "notify";
         User = "matrix-synapse";