Validate session cookies in Next.js App router

You can get the cookie name with Lucia.sessionCookieName and validate the session cookie with Lucia.validateSession(). Delete the session cookie if it's invalid and create a new session cookie when the expiration gets extended, which is indicated by Session.fresh. We have to wrap it inside a try/catch block since Next.js doesn't allow you to set cookies when rendering the page. This is a known issue but Vercel has yet to acknowledge or address the issue.

We recommend wrapping the function with cache() so it can be called multiple times without incurring multiple database calls.

CSRF protection is only handled by Next.js when using form actions. If you're using Route Handlers, it must be implemented by yourself (see below).

import { lucia } from "@/utils/auth";
import { cookies } from "next/headers";

const getUser = cache(async () => {
	const sessionId = cookies().get(lucia.sessionCookieName)?.value ?? null;
	if (!sessionId) return null;
	const { user, session } = await lucia.validateSession(sessionId);
	try {
		if (session && session.fresh) {
			const sessionCookie = lucia.createSessionCookie(session.id);
			cookies().set(sessionCookie.name, sessionCookie.value, sessionCookie.attributes);
		}
		if (!session) {
			const sessionCookie = lucia.createBlankSessionCookie();
			cookies().set(sessionCookie.name, sessionCookie.value, sessionCookie.attributes);
		}
	} catch {
		// Next.js throws error when attempting to set cookies when rendering page
	}
	return user;
});

Set sessionCookie.expires option to false so the session cookie persists for a longer period.

import { Lucia } from "lucia";

const lucia = new Lucia(adapter, {
	sessionCookie: {
		expires: false,
		attributes: {
			// set to `true` when using HTTPS
			secure: process.env.NODE_ENV === "production"
		}
	}
});

You can now use getUser() in server components, including server actions.

// app/api/page.tsx
import { redirect } from "next/navigation";

async function Page() {
	const user = await getUser();
	if (!user) {
		redirect("/login");
	}
	// ...
	async function action() {
		"use server";
		const user = await getUser();
		if (!user) {
			redirect("/login");
		}
		// ...
	}
	// ...
}

For Route Handlers, since Next.js does not implement CSRF protection for Route Handlers, CSRF protection must be implemented when dealing with forms if you're dealing with forms. This can be easily done by comparing the Origin and Host header. We recommend using middleware for this.

// middleware.ts
import { verifyRequestOrigin } from "lucia";
import { NextResponse } from "next/server";
import type { NextRequest } from "next/server";

export async function middleware(request: NextRequest): Promise<NextResponse> {
	if (request.method === "GET") {
		return NextResponse.next();
	}
	const originHeader = request.headers.get("Origin");
	// NOTE: You may need to use `X-Forwarded-Host` instead
	const hostHeader = request.headers.get("Host");
	if (!originHeader || !hostHeader || !verifyRequestOrigin(originHeader, [hostHeader])) {
		return new NextResponse(null, {
			status: 403
		});
	}
	return NextResponse.next();
}