Use fileSystem on an API Route with NextJS deployed on Vercel - node.js

Question

I need to use fileStystem methods as readdirSync on an API Route in NextJS. It works locally but when deployed on Vercel, the request responds with a 500 status code.
This is Vercel's Funcion Logs:
catch Error: ENOENT: no such file or directory, scandir '/var/task/_posts'
at Object.readdirSync (fs.js:1043:3)
at getAllArticles (/var/task/.next/server/chunks/230.js:135:67)
at __WEBPACK_DEFAULT_EXPORT__ (/var/task/.next/server/pages/api/search.js:37:93)
at Object.apiResolver (/var/task/node_modules/next/dist/server/api-utils.js:101:15)
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at async Server.handleApiRequest (/var/task/node_modules/next/dist/server/next-server.js:770:9)
at async Object.fn (/var/task/node_modules/next/dist/server/next-server.js:661:37)
at async Router.execute (/var/task/node_modules/next/dist/server/router.js:205:32)
at async Server.run (/var/task/node_modules/next/dist/server/next-server.js:841:29)
at async Server.handleRequest (/var/task/node_modules/next/dist/server/next-server.js:292:20) {
errno: -2,
syscall: 'scandir',
code: 'ENOENT',
path: '/var/task/_posts'
}
This is the API Route itself (/pages/api/search.ts):
export default (req: NextApiRequest, res: NextApiResponse) => {
const { query } = req;
try {
if (query.q) {
const posts = getAllArticles(ArticleTypes.POSTS, ['slug', 'href', 'title', 'category'], {
hints: {
hint: query.q as string,
fields: ['title', 'category'],
},
}).map((post) => post.data);
const projects = getAllArticles(ArticleTypes.PROJECTS, ['slug', 'href', 'title', 'category', 'technologies'], {
hints: {
hint: query.q as string,
fields: ['title', 'category', 'technologies'],
},
}).map((project) => project.data);
res.status(200).json({
...(posts.length > 0) && { posts },
...(projects.length > 0) && { projects },
});
} else {
res.status(422).send('El parámetro "q" es necesario.');
}
} catch (e) {
res.status(500).send('Ha ocurrido un error mientras se intentaba hacer la búsqueda.');
}
};
And this is the getAllArticles() function used in it:
export const getAllArticles = (
type: ArticleTypes,
items?: string[],
filters?: IFilters,
): IArticle[] => {
const articlesPath = join(process.cwd(), `_${type}`);
const articlesNames = fs
.readdirSync(articlesPath)
.filter((path) => /\.mdx$/.test(path));
const mergedItems: string[] = Array.from(new Set([
...(items && items.length > 0) ? items : [],
...(filters?.hints && filters.hints.fields.length > 0) ? filters.hints.fields : [],
]));
const allArticles = articlesNames
.map((article) => getArticle(type,
path.parse(article).name,
mergedItems.length > 0
? mergedItems
: undefined));
const filteredArticles = filterArticles(type, allArticles, filters);
return filteredArticles;
};
So I am currently using fs.readdirSync for reading .mdx files. As I noted before, this runs perfectly well locally but not when deployed on Vercel. Do I nees to configure any kind of config files or anything?
Thank you so much!