feat: add structured logging with request correlation (#115)

Author: rubenhensen

package-lock.json

@@ -53,6 +53,7 @@
 		"@privacybydesign/yivi-core": "^1.0.0",
 		"@privacybydesign/yivi-css": "^1.0.1",
 		"@privacybydesign/yivi-web": "^1.0.1",
+		"pino": "^10.3.1",
 		"sass": "^1.100.0",
 		"svelte-i18n": "^4.0.1"
 	},

package.json

@@ -14,6 +14,8 @@ declare global {
 				yiviAttributes: Record<string, string>;
 			} | null;
 			locale: string;
+			requestId: string;
+			log: import('$lib/server/logger').Logger;
 		}
 		// interface PageData {}
 		// interface PageState {}

src/app.d.ts

@@ -1,8 +1,25 @@
-import type { Handle } from '@sveltejs/kit';
+import type { Handle, HandleServerError } from '@sveltejs/kit';
 import { resolveSession } from '$lib/server/auth/session';
 import { normalizeLocale } from '$lib/i18n';
+import { logger } from '$lib/server/logger';
+
+const REQUEST_ID_MAX = 64;
+
+// Use a client-supplied X-Request-Id when present (sanitised), otherwise mint
+// one. Keeps correlation across a proxy without trusting arbitrary input.
+function resolveRequestId(header: string | null): string {
+	if (header) {
+		const cleaned = header.replace(/[^a-zA-Z0-9_-]/g, '').slice(0, REQUEST_ID_MAX);
+		if (cleaned) return cleaned;
+	}
+	return crypto.randomUUID();
+}
 
 export const handle: Handle = async ({ event, resolve }) => {
+	const requestId = resolveRequestId(event.request.headers.get('x-request-id'));
+	event.locals.requestId = requestId;
+	event.locals.log = logger.child({ requestId });
+
 	const token = event.cookies.get('pg_session');
 
 	if (token) {
@@ -19,12 +36,39 @@ export const handle: Handle = async ({ event, resolve }) => {
 	// per-request inside `+layout.ts`.
 	event.locals.locale = normalizeLocale(event.request.headers.get('accept-language'));
 
+	const start = performance.now();
 	const response = await resolve(event);
+	const durationMs = Math.round(performance.now() - start);
 
+	response.headers.set('X-Request-Id', requestId);
 	response.headers.set('X-Frame-Options', 'DENY');
 	response.headers.set('X-Content-Type-Options', 'nosniff');
 	response.headers.set('Referrer-Policy', 'strict-origin-when-cross-origin');
 	response.headers.set('Permissions-Policy', 'camera=(), microphone=(), geolocation=()');
 
+	// Skip the noisy liveness/readiness probes.
+	const path = event.url.pathname;
+	if (path !== '/health' && path !== '/readyz') {
+		event.locals.log.info(
+			{ method: event.request.method, path, status: response.status, durationMs },
+			'request'
+		);
+	}
+
 	return response;
 };
+
+export const handleError: HandleServerError = ({ error, event, status, message }) => {
+	logger.error(
+		{
+			requestId: event.locals.requestId,
+			method: event.request.method,
+			path: event.url.pathname,
+			status,
+			err: error instanceof Error ? { message: error.message, stack: error.stack } : String(error)
+		},
+		'unhandled error'
+	);
+
+	return { message };
+};

src/hooks.server.ts

@@ -0,0 +1,12 @@
+import pino from 'pino';
+import { env } from '$env/dynamic/private';
+
+// Structured JSON logger to stdout. No transport is configured, which keeps it
+// robust under the bundled adapter-node server; set LOG_LEVEL to control
+// verbosity (default: info). Request-scoped child loggers (carrying a
+// requestId) are created in hooks.server.ts and exposed via `event.locals.log`.
+export const logger = pino({
+	level: env.LOG_LEVEL ?? 'info'
+});
+
+export type Logger = typeof logger;

src/lib/server/logger.ts

@@ -3,6 +3,7 @@ import { dnsVerifications } from '$lib/server/db/schema';
 import { eq } from 'drizzle-orm';
 import { randomBytes } from 'crypto';
 import { resolve } from 'dns/promises';
+import { logger } from '$lib/server/logger';
 
 export async function getOrCreateDnsVerification(orgId: string, domain: string) {
 	const existing = await db
@@ -64,12 +65,15 @@ export async function verifyDns(orgId: string): Promise<{
 		}
 	} catch (err) {
 		const code = (err as NodeJS.ErrnoException)?.code;
-		console.error('[dns-verification] resolve failed', {
-			orgId,
-			domain: record.domain,
-			code,
-			message: err instanceof Error ? err.message : String(err)
-		});
+		logger.error(
+			{
+				orgId,
+				domain: record.domain,
+				code,
+				err: err instanceof Error ? err.message : String(err)
+			},
+			'dns resolve failed'
+		);
 		await db
 			.update(dnsVerifications)
 			.set({ lastCheckedAt: new Date() })

src/lib/server/services/dns-verification.ts

@@ -1,9 +1,9 @@
 import type { RequestHandler } from './$types';
 
-export const POST: RequestHandler = async ({ request }) => {
+export const POST: RequestHandler = async ({ request, locals }) => {
 	try {
 		const text = await request.text();
-		console.warn('[csp-report]', text.slice(0, 4096));
+		locals.log.warn({ report: text.slice(0, 4096) }, 'csp violation');
 	} catch {
 		// ignore — best-effort
 	}