From 7fc3b25d21c6c4f1802f34b1ae065a65cac3001b Mon Sep 17 00:00:00 2001
From: Danny Martini <danny@n8n.io>
Date: Fri, 25 Oct 2024 10:24:39 +0200
Subject: [PATCH] fix(core): Fix Message Event Bus Metrics not counting up for
 labeled metrics (#11396)

---
 packages/cli/jest.config.js                   |   1 +
 ...rometheus-metrics.service.unmocked.test.ts | 109 ++++++++++++++++++
 .../src/metrics/prometheus-metrics.service.ts |   5 +-
 3 files changed, 113 insertions(+), 2 deletions(-)
 create mode 100644 packages/cli/src/metrics/__tests__/prometheus-metrics.service.unmocked.test.ts

diff --git a/packages/cli/jest.config.js b/packages/cli/jest.config.js
index 72a653e07d..5420435df2 100644
--- a/packages/cli/jest.config.js
+++ b/packages/cli/jest.config.js
@@ -14,4 +14,5 @@ module.exports = {
 	],
 	coveragePathIgnorePatterns: ['/src/databases/migrations/'],
 	testTimeout: 10_000,
+	prettierPath: null,
 };
diff --git a/packages/cli/src/metrics/__tests__/prometheus-metrics.service.unmocked.test.ts b/packages/cli/src/metrics/__tests__/prometheus-metrics.service.unmocked.test.ts
new file mode 100644
index 0000000000..e485bbe435
--- /dev/null
+++ b/packages/cli/src/metrics/__tests__/prometheus-metrics.service.unmocked.test.ts
@@ -0,0 +1,109 @@
+import { GlobalConfig } from '@n8n/config';
+import type express from 'express';
+import { mock } from 'jest-mock-extended';
+import type { InstanceSettings } from 'n8n-core';
+import promClient from 'prom-client';
+
+import { EventMessageWorkflow } from '@/eventbus/event-message-classes/event-message-workflow';
+import type { EventService } from '@/events/event.service';
+import { mockInstance } from '@test/mocking';
+
+import { MessageEventBus } from '../../eventbus/message-event-bus/message-event-bus';
+import { PrometheusMetricsService } from '../prometheus-metrics.service';
+
+jest.unmock('@/eventbus/message-event-bus/message-event-bus');
+
+const customPrefix = 'custom_';
+
+const eventService = mock<EventService>();
+const instanceSettings = mock<InstanceSettings>({ instanceType: 'main' });
+const app = mock<express.Application>();
+const eventBus = new MessageEventBus(
+	mock(),
+	mock(),
+	mock(),
+	mock(),
+	mock(),
+	mock(),
+	mock(),
+	mock(),
+);
+
+describe('workflow_success_total', () => {
+	test('support workflow id labels', async () => {
+		// ARRANGE
+		const globalConfig = mockInstance(GlobalConfig, {
+			endpoints: {
+				metrics: {
+					prefix: '',
+					includeMessageEventBusMetrics: true,
+					includeWorkflowIdLabel: true,
+				},
+			},
+		});
+
+		const prometheusMetricsService = new PrometheusMetricsService(
+			mock(),
+			eventBus,
+			globalConfig,
+			eventService,
+			instanceSettings,
+		);
+
+		await prometheusMetricsService.init(app);
+
+		// ACT
+		const event = new EventMessageWorkflow({
+			eventName: 'n8n.workflow.success',
+			payload: { workflowId: '1234' },
+		});
+
+		eventBus.emit('metrics.eventBus.event', event);
+
+		// ASSERT
+		const workflowSuccessCounter =
+			await promClient.register.getSingleMetricAsString('workflow_success_total');
+
+		expect(workflowSuccessCounter).toMatchInlineSnapshot(`
+"# HELP workflow_success_total Total number of n8n.workflow.success events.
+# TYPE workflow_success_total counter
+workflow_success_total{workflow_id="1234"} 1"
+`);
+	});
+
+	test('support a custom prefix', async () => {
+		// ARRANGE
+		const globalConfig = mockInstance(GlobalConfig, {
+			endpoints: {
+				metrics: {
+					prefix: customPrefix,
+				},
+			},
+		});
+
+		const prometheusMetricsService = new PrometheusMetricsService(
+			mock(),
+			eventBus,
+			globalConfig,
+			eventService,
+			instanceSettings,
+		);
+
+		await prometheusMetricsService.init(app);
+
+		// ACT
+		const event = new EventMessageWorkflow({
+			eventName: 'n8n.workflow.success',
+			payload: { workflowId: '1234' },
+		});
+
+		eventBus.emit('metrics.eventBus.event', event);
+
+		// ASSERT
+		const versionInfoMetric = promClient.register.getSingleMetric(`${customPrefix}version_info`);
+
+		if (!versionInfoMetric) {
+			fail(`Could not find a metric called "${customPrefix}version_info"`);
+		}
+	});
+});
diff --git a/packages/cli/src/metrics/prometheus-metrics.service.ts b/packages/cli/src/metrics/prometheus-metrics.service.ts
index 2565b0a6b1..41714d25ad 100644
--- a/packages/cli/src/metrics/prometheus-metrics.service.ts
+++ b/packages/cli/src/metrics/prometheus-metrics.service.ts
@@ -211,7 +211,6 @@ export class PrometheusMetricsService {
 				help: `Total number of ${eventName} events.`,
 				labelNames: Object.keys(labels),
 			});
-			counter.labels(labels).inc(0);
 			this.counters[eventName] = counter;
 		}
 
@@ -224,7 +223,9 @@ export class PrometheusMetricsService {
 		this.eventBus.on('metrics.eventBus.event', (event: EventMessageTypes) => {
 			const counter = this.toCounter(event);
 			if (!counter) return;
-			counter.inc(1);
+
+			const labels = this.toLabels(event);
+			counter.inc(labels, 1);
 		});
 	}