Add healthcheck endpoint

src/routes/health/+server.ts

@@ -0,0 +1,50 @@
+import { storagePath } from '$lib';
+import { json } from '@sveltejs/kit';
+import { stat, access, constants } from 'fs/promises';
+import type { RequestHandler } from './$types';
+
+type Status = 'OK' | 'ERROR';
+type Result = { status: Status; checks: Checks };
+
+type Checks = { [key: string]: CheckResult };
+type CheckResult = true | string;
+
+const fileExists = async (path: string) => !!(await stat(path).catch(() => false));
+const isDirectory = async (path: string) =>
+	!!(await stat(path)
+		.then((s) => s.isDirectory())
+		.catch(() => false));
+const isWritable = async (path: string) =>
+	await access(path, constants.W_OK)
+		.then(() => true)
+		.catch(() => false);
+
+const checkStoragePath = async (path: string): Promise<CheckResult> => {
+	if (!fileExists(path)) {
+		return '`STORAGE_PATH` does not exist';
+	} else if (!isDirectory(path)) {
+		return '`STORAGE_PATH` is not a directory';
+	} else if (!isWritable(path)) {
+		return '`STORAGE_PATH` is not writable';
+	}
+	return true;
+};
+
+export const GET: RequestHandler = async () => {
+	const storagePathResult = await checkStoragePath(storagePath);
+
+	const checks: Checks = {
+		storagePath: storagePathResult,
+	};
+
+	const healthy = Object.values(checks)
+		.map((r) => (r === true ? true : false))
+		.reduce((prev, next) => prev && next, true);
+
+	const status = healthy ? 'OK' : 'ERROR';
+
+	const result: Result = { status, checks };
+	const httpStatus = healthy ? 200 : 500;
+
+	return json(result, { status: httpStatus, headers: { healthy: healthy.toString() } });
+};