Implemented missing PROMETHEUS_ROUTE_MIDDLEWARE support.

Author: thirsch

config/prometheus.php

@@ -39,6 +39,19 @@
 
     'metrics_route_path' => env('PROMETHEUS_METRICS_ROUTE_PATH', 'metrics'),
 
+    /*
+    |--------------------------------------------------------------------------
+    | Metrics Route Middleware
+    |--------------------------------------------------------------------------
+    |
+    | The name of a middleware to be used for the metrics route, e.g. a basic-auth check.
+    |
+    | This is only applicable if metrics_route_enabled is set to true.
+    |
+    */
+
+    'metrics_route_middleware' => env('PROMETHEUS_METRICS_ROUTE_MIDDLEWARE', null),
+
     /*
     |--------------------------------------------------------------------------
     | Storage Adapter

src/PrometheusServiceProvider.php

@@ -83,19 +83,23 @@ private function loadRoutes()
         /** @var Route $route */
         $isLumen = mb_strpos($this->app->version(), 'Lumen') !== false;
         if ($isLumen) {
-            $router->get(
+            $route = $router->get(
                 config('prometheus.metrics_route_path'),
                 [
                     'as' => 'metrics',
                     'uses' => MetricsController::class . '@getMetrics',
                 ]
             );
         } else {
-            $router->get(
+            $route = $router->get(
                 config('prometheus.metrics_route_path'),
                 MetricsController::class . '@getMetrics'
             )->name('metrics');
         }
+
+        if ($middleware = config('prometheus.metrics_route_middleware')) {
+            $route->middleware($middleware);
+        }
     }
 
     private function configPath($path) : string