feat(core): Add metric for active workflow count (#13420)

packages/@n8n/config/src/configs/endpoints.config.ts

@@ -57,6 +57,10 @@ class PrometheusMetricsConfig {
 	/** How often (in seconds) to update queue metrics. */
 	@Env('N8N_METRICS_QUEUE_METRICS_INTERVAL')
 	queueMetricsInterval: number = 20;
+
+	/** How often (in seconds) to update active workflow metric */
+	@Env('N8N_METRICS_ACTIVE_WORKFLOW_METRIC_INTERVAL')
+	activeWorkflowCountInterval: number = 60;
 }
 
 @Config

packages/@n8n/config/test/config.test.ts

@@ -173,6 +173,7 @@ describe('GlobalConfig', () => {
 				includeApiStatusCodeLabel: false,
 				includeQueueMetrics: false,
 				queueMetricsInterval: 20,
+				activeWorkflowCountInterval: 60,
 			},
 			additionalNonUIRoutes: '',
 			disableProductionWebhooksOnMainProcess: false,