metrics.ts50 lines · main

1	import type { MiddlewareHandler } from 'hono';
2
3	import { incCounter, observeHistogram } from '../lib/metrics.js';
4	import { recordAuthRoute5xx } from '../services/auth-reliability.js';
5
6	/**
7	* Records `http_requests_total{method,status,route}` and
8	* `http_request_duration_ms{method,route}` for every request that reaches
9	* a handler. Uses Hono's matched-route pattern (`c.req.routePath`) rather
10	* than the raw path so dynamic segments don't blow up label cardinality —
11	* `/v1/projects/p_abc.../functions/foo` becomes the same label as
12	* `/v1/projects/p_xyz.../functions/bar`.
13	*
14	* Skips its own `/metrics` endpoint to keep prometheus scrapes from
15	* polluting the metric they're scraping.
16	*/
17	export const metricsMiddleware = (): MiddlewareHandler => async (c, next) => {
18	// Hono v4 exposes the matched pattern via `routePath`. Falls back to the
19	// raw path if for some reason it's missing (older middleware order, etc).
20	const start = performance.now();
21	await next();
22	const durationMs = performance.now() - start;
23
24	const route =
25	typeof (c.req as { routePath?: unknown }).routePath === 'string'
26	? ((c.req as { routePath: string }).routePath || c.req.path)
27	: c.req.path;
28
29	if (route === '/metrics') return;
30
31	const labels = {
32	method: c.req.method,
33	route,
34	};
35	incCounter('http_requests_total', { ...labels, status: String(c.res.status) });
36	observeHistogram('http_request_duration_ms', durationMs, labels);
37
38	// S6.3: auth-path 5xx for operator snapshot + Prometheus.
39	const status = c.res.status;
40	if (status >= 500) {
41	const path = c.req.path;
42	if (
43	path.includes('/auth') ||
44	path.includes('/auth-tenant') ||
45	path.includes('/v1/auth')
46	) {
47	recordAuthRoute5xx();
48	}
49	}
50	};