fix(core): Respect prefix for all Prometheus metrics

packages/cli/BREAKING-CHANGES.md

@@ -2,6 +2,16 @@
 
 This list shows all the versions which include breaking changes and how to upgrade.
 
+## 1.52.0
+
+### What changed?
+
+Prometheus metrics enabled via `N8N_METRICS_INCLUDE_DEFAULT_METRICS` and `N8N_METRICS_INCLUDE_API_ENDPOINTS` were fixed to include the default `n8n_` prefix.
+
+### When is action necessary?
+
+If you are using Prometheus metrics from these categories and are using a non-empty prefix, please update those metrics to match their new prefixed names.
+
 ## 1.47.0
 
 ### What changed?

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

@@ -86,7 +86,7 @@ describe('PrometheusMetricsService', () => {
 			expect(service.counters.cacheUpdatesTotal?.inc).toHaveBeenCalledWith(0);
 		});
 
-		it('should set up API metrics with `express-prom-bundle`', async () => {
+		it('should set up route metrics with `express-prom-bundle`', async () => {
 			config.set('endpoints.metrics.includeApiEndpoints', true);
 			config.set('endpoints.metrics.includeApiPathLabel', true);
 			config.set('endpoints.metrics.includeApiMethodLabel', true);

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

@@ -10,8 +10,7 @@ import { CacheService } from '@/services/cache/cache.service';
 import { MessageEventBus } from '@/eventbus/MessageEventBus/MessageEventBus';
 import { EventMessageTypeNames } from 'n8n-workflow';
 import type { EventMessageTypes } from '@/eventbus';
-
-type MetricCategory = 'default' | 'api' | 'cache' | 'logs';
+import type { Includes, MetricCategory, MetricLabel } from './types';
 
 @Service()
 export class PrometheusMetricsService {
@@ -24,10 +23,10 @@ export class PrometheusMetricsService {
 
 	private readonly prefix = config.getEnv('endpoints.metrics.prefix');
 
-	private readonly includes = {
+	private readonly includes: Includes = {
 		metrics: {
 			default: config.getEnv('endpoints.metrics.includeDefaultMetrics'),
-			api: config.getEnv('endpoints.metrics.includeApiEndpoints'),
+			routes: config.getEnv('endpoints.metrics.includeApiEndpoints'),
 			cache: config.getEnv('endpoints.metrics.includeCacheMetrics'),
 			logs: config.getEnv('endpoints.metrics.includeMessageEventBusMetrics'),
 		},
@@ -60,8 +59,20 @@ export class PrometheusMetricsService {
 	}
 
 	disableAllMetrics() {
-		for (const metric of Object.keys(this.includes.metrics) as MetricCategory[]) {
-			this.includes.metrics[metric] = false;
+		for (const metric in this.includes.metrics) {
+			this.includes.metrics[metric as MetricCategory] = false;
+		}
+	}
+
+	enableLabels(labels: MetricLabel[]) {
+		for (const label of labels) {
+			this.includes.labels[label] = true;
+		}
+	}
+
+	disableAllLabels() {
+		for (const label in this.includes.labels) {
+			this.includes.labels[label as MetricLabel] = false;
 		}
 	}
 
@@ -98,7 +109,7 @@ export class PrometheusMetricsService {
 	 * Set up metrics for server routes with `express-prom-bundle`
 	 */
 	private initRouteMetrics(app: express.Application) {
-		if (!this.includes.metrics.api) return;
+		if (!this.includes.metrics.routes) return;
 
 		const metricsMiddleware = promBundle({
 			autoregister: false,
@@ -126,11 +137,25 @@ export class PrometheusMetricsService {
 	private mountMetricsEndpoint(app: express.Application) {
 		app.get('/metrics', async (_req: express.Request, res: express.Response) => {
 			const metrics = await promClient.register.metrics();
+			const prefixedMetrics = this.addPrefixToMetrics(metrics);
 			res.setHeader('Content-Type', promClient.register.contentType);
-			res.send(metrics).end();
+			res.send(prefixedMetrics).end();
 		});
 	}
 
+	private addPrefixToMetrics(metrics: string) {
+		return metrics
+			.split('\n')
+			.map((rawLine) => {
+				const line = rawLine.trim();
+
+				if (!line || line.startsWith('#') || line.startsWith(this.prefix)) return rawLine;
+
+				return this.prefix + line;
+			})
+			.join('\n');
+	}
+
 	/**
 	 * Set up cache metrics: `n8n_cache_hits_total`, `n8n_cache_misses_total`, and
 	 * `n8n_cache_updates_total`

packages/cli/src/metrics/types.ts

@@ -0,0 +1,14 @@
+export type MetricCategory = 'default' | 'routes' | 'cache' | 'logs';
+
+export type MetricLabel =
+	| 'credentialsType'
+	| 'nodeType'
+	| 'workflowId'
+	| 'apiPath'
+	| 'apiMethod'
+	| 'apiStatusCode';
+
+export type Includes = {
+	metrics: Record<MetricCategory, boolean>;
+	labels: Record<MetricLabel, boolean>;
+};

packages/cli/test/integration/prometheus-metrics.test.ts

@@ -26,6 +26,7 @@ describe('Metrics', () => {
 
 	beforeEach(() => {
 		prometheusService.disableAllMetrics();
+		prometheusService.disableAllLabels();
 	});
 
 	it('should return n8n version', async () => {
@@ -51,7 +52,9 @@ describe('Metrics', () => {
 
 		const { version, major, minor, patch } = n8nVersion;
 
-		expect(toLines(response)).toContain(
+		const lines = toLines(response);
+
+		expect(lines).toContain(
 			`n8n_test_version_info{version="v${version}",major="${major}",minor="${minor}",patch="${patch}"} 1`,
 		);
 	});
@@ -73,7 +76,10 @@ describe('Metrics', () => {
 		 */
 		expect(response.status).toEqual(200);
 		expect(response.type).toEqual('text/plain');
-		expect(toLines(response)).toContain('nodejs_heap_space_size_total_bytes{space="read_only"} 0');
+
+		const lines = toLines(response);
+
+		expect(lines).toContain('n8n_test_nodejs_heap_space_size_total_bytes{space="read_only"} 0');
 	});
 
 	it('should not return default metrics if disabled', async () => {
@@ -146,4 +152,61 @@ describe('Metrics', () => {
 		expect(lines).not.toContain('n8n_test_cache_misses_total 0');
 		expect(lines).not.toContain('n8n_test_cache_updates_total 0');
 	});
+
+	it('should return route metrics if enabled', async () => {
+		/**
+		 * Arrange
+		 */
+		prometheusService.enableMetric('routes');
+		await prometheusService.init(server.app);
+		await agent.get('/api/v1/workflows');
+
+		/**
+		 * Act
+		 */
+		const response = await agent.get('/metrics');
+
+		/**
+		 * Assert
+		 */
+		expect(response.status).toEqual(200);
+		expect(response.type).toEqual('text/plain');
+
+		const lines = toLines(response);
+
+		expect(lines).toContain('n8n_test_http_request_duration_seconds_count 1');
+		expect(lines).toContainEqual(
+			expect.stringContaining('n8n_test_http_request_duration_seconds_sum'),
+		);
+		expect(lines).toContainEqual(
+			expect.stringContaining('n8n_test_http_request_duration_seconds_bucket'),
+		);
+	});
+
+	it('should return labels in route metrics if enabled', async () => {
+		/**
+		 * ARrange
+		 */
+		prometheusService.enableMetric('routes');
+		prometheusService.enableLabels(['apiMethod', 'apiPath', 'apiStatusCode']);
+		await prometheusService.init(server.app);
+		await agent.get('/webhook-test/some-uuid');
+
+		/**
+		 * Act
+		 */
+		const response = await agent.get('/metrics');
+
+		/**
+		 * Assert
+		 */
+		expect(response.status).toEqual(200);
+		expect(response.type).toEqual('text/plain');
+
+		const lines = toLines(response);
+
+		expect(lines).toContainEqual(expect.stringContaining('method="GET"'));
+		expect(lines).toContainEqual(expect.stringContaining('path="/webhook-test/some-uuid"'));
+		expect(lines).toContainEqual(expect.stringContaining('status_code="404"'));
+	});
 });