feat(core): Hackmation - Add last activity metric (#13237)

packages/cli/src/metrics/__tests__/prometheus-metrics.service.test.ts

@@ -38,6 +38,13 @@ describe('PrometheusMetricsService', () => {
 				includeApiStatusCodeLabel: false,
 				includeQueueMetrics: false,
 			},
+			rest: 'rest',
+			form: 'form',
+			formTest: 'form-test',
+			formWaiting: 'form-waiting',
+			webhook: 'webhook',
+			webhookTest: 'webhook-test',
+			webhookWaiting: 'webhook-waiting',
 		},
 	});
 
@@ -145,10 +152,16 @@ describe('PrometheusMetricsService', () => {
 				includeStatusCode: false,
 			});
 
+			expect(promClient.Gauge).toHaveBeenNthCalledWith(2, {
+				name: 'n8n_last_activity',
+				help: 'last instance activity (backend request).',
+				labelNames: ['timestamp'],
+			});
+
 			expect(app.use).toHaveBeenCalledWith(
 				[
-					'/rest/',
 					'/api/',
+					'/rest/',
 					'/webhook/',
 					'/webhook-waiting/',
 					'/webhook-test/',

packages/cli/src/metrics/prometheus-metrics.service.ts

@@ -117,7 +117,8 @@ export class PrometheusMetricsService {
 	}
 
 	/**
-	 * Set up metrics for server routes with `express-prom-bundle`
+	 * Set up metrics for server routes with `express-prom-bundle`. The same
+	 * middleware is also utilized for an instance activity metric
 	 */
 	private initRouteMetrics(app: express.Application) {
 		if (!this.includes.metrics.routes) return;
@@ -130,18 +131,31 @@ export class PrometheusMetricsService {
 			includeStatusCode: this.includes.labels.apiStatusCode,
 		});
 
+		const activityGauge = new promClient.Gauge({
+			name: this.prefix + 'last_activity',
+			help: 'last instance activity (backend request).',
+			labelNames: ['timestamp'],
+		});
+
+		activityGauge.set({ timestamp: new Date().toISOString() }, 1);
+
 		app.use(
 			[
-				'/rest/',
 				'/api/',
-				'/webhook/',
+				`/${this.globalConfig.endpoints.rest}/`,
-				'/webhook-waiting/',
+				`/${this.globalConfig.endpoints.webhook}/`,
-				'/webhook-test/',
+				`/${this.globalConfig.endpoints.webhookWaiting}/`,
-				'/form/',
+				`/${this.globalConfig.endpoints.webhookTest}/`,
-				'/form-waiting/',
+				`/${this.globalConfig.endpoints.form}/`,
-				'/form-test/',
+				`/${this.globalConfig.endpoints.formWaiting}/`,
+				`/${this.globalConfig.endpoints.formTest}/`,
 			],
-			metricsMiddleware,
+			(req, res, next) => {
+				activityGauge.reset();
+				activityGauge.set({ timestamp: new Date().toISOString() }, 1);
+
+				metricsMiddleware(req, res, next);
+			},
 		);
 	}