initial commit

fluxer_api/src/middleware/MetricsMiddleware.ts

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+/*
+ * Copyright (C) 2026 Fluxer Contributors
+ *
+ * This file is part of Fluxer.
+ *
+ * Fluxer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Fluxer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {createMiddleware} from 'hono/factory';
+import type {HonoEnv} from '~/App';
+import {getMetricsService} from '~/infrastructure/MetricsService';
+
+function normalizePath(path: string): string {
+	return path
+		.replace(/\/\d{17,20}/g, '/:id')
+		.replace(/\/[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}/gi, '/:uuid')
+		.replace(/\/[A-Za-z0-9_-]{6,}/g, (match) => {
+			if (match.match(/^\/[0-9]+$/)) {
+				return '/:id';
+			}
+			return match;
+		});
+}
+
+export const MetricsMiddleware = createMiddleware<HonoEnv>(async (ctx, next) => {
+	const metrics = getMetricsService();
+	if (!metrics.isEnabled()) {
+		await next();
+		return;
+	}
+
+	const start = performance.now();
+	const method = ctx.req.method;
+	const path = new URL(ctx.req.url).pathname;
+
+	try {
+		await next();
+	} finally {
+		const durationMs = performance.now() - start;
+		const normalizedPath = normalizePath(path);
+		const status = ctx.res.status;
+
+		metrics.histogram({
+			name: 'api.latency',
+			dimensions: {
+				method,
+				path: normalizedPath,
+				status: String(status),
+			},
+			valueMs: durationMs,
+		});
+
+		if (status >= 200 && status < 300) {
+			metrics.counter({
+				name: 'api.request.2xx',
+				dimensions: {
+					method,
+					path: normalizedPath,
+					status: String(status),
+				},
+				value: 1,
+			});
+		} else if (status >= 400 && status < 500) {
+			metrics.counter({
+				name: 'api.request.4xx',
+				dimensions: {
+					method,
+					path: normalizedPath,
+					status: String(status),
+				},
+				value: 1,
+			});
+		} else if (status >= 500 && status < 600) {
+			metrics.counter({
+				name: 'api.request.5xx',
+				dimensions: {
+					method,
+					path: normalizedPath,
+					status: String(status),
+				},
+				value: 1,
+			});
+		}
+	}
+});