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GitHub OAuth in Next.js Pages Router

Before starting, make sure you’ve setup Lucia and your database.

This guide will cover how to implement GitHub OAuth using Lucia in Next.js Pages Router. It will have 3 parts:

  • A sign up page
  • An endpoint to authenticate users with GitHub
  • A profile page with a logout button

As a general overview of OAuth, the user is redirected to github.com to be authenticated, and GitHub redirects the user back to your application with a code that can be validated and used to get the user’s identity.

Clone project#

You can get started immediately by cloning the Next.js example from the repository.

npx degit lucia-auth/examples/nextjs-pages/github-oauth <directory_name>

Alternatively, you can open it in StackBlitz.

Create an OAuth app#

Create a GitHub OAuth app. Set the redirect uri to:

http://localhost:3000/api/login/github/callback

Copy and paste the client id and client secret into your .env file:

# .env
GITHUB_CLIENT_ID="..."
GITHUB_CLIENT_SECRET="..."

Update your database#

Add a username column to your table. It should be a string (TEXT, VARCHAR etc) type (optionally unique).

Make sure you update Lucia.DatabaseUserAttributes whenever you add any new columns to the user table.

// app.d.ts

/// <reference types="lucia" />
declare namespace Lucia {
	type Auth = import("./lucia.js").Auth;
	type DatabaseUserAttributes = {
		username: string;
	};
	type DatabaseSessionAttributes = {};
}

Configure Lucia#

We’ll expose the user’s GitHub username to the User object by defining getUserAttributes.

// auth/lucia.ts
import { lucia } from "lucia";
import { nextjs_future } from "lucia/middleware";

export const auth = lucia({
	adapter: ADAPTER,
	env: process.env.NODE_ENV === "development" ? "DEV" : "PROD",
	middleware: nextjs_future(),

	getUserAttributes: (data) => {
		return {
			githubUsername: data.username
		};
	}
});

export type Auth = typeof auth;

Initialize the OAuth integration#

Install the OAuth integration.

npm i @lucia-auth/oauth
pnpm add @lucia-auth/oauth
yarn add @lucia-auth/oauth

Import the GitHub OAuth integration, and initialize it using your credentials.

// auth/lucia.ts
import { lucia } from "lucia";
import { nextjs } from "lucia/middleware";

import { github } from "@lucia-auth/oauth/providers";

export const auth = lucia({
	// ...
});

export const githubAuth = github(auth, {
	clientId: process.env.GITHUB_CLIENT_ID ?? "",
	clientSecret: process.env.GITHUB_CLIENT_SECRET ?? ""
});

export type Auth = typeof auth;

Sign in page#

Create pages/login.tsx. It will have a “Sign in with GitHub” button (actually a link).

// pages/login.tsx

const Page = () => {
	return (
		<>
			<h1>Sign in</h1>
			<a href="/api/login/github">Sign in with GitHub</a>
		</>
	);
};

export default Page;

When a user clicks the link, the destination (/api/login/github) will redirect the user to GitHub to be authenticated.

Generate authorization url#

Create pages/api/login/github.ts and handle GET requests. GithubProvider.getAuthorizationUrl() will create a new GitHub authorization url, where the user will be authenticated in github.com. When generating an authorization url, Lucia will also create a new state. This should be stored as a http-only cookie to be used later.

// pages/api/login/github.ts
import { auth, githubAuth } from "@/auth/lucia";
import { serializeCookie } from "lucia/utils";

import type { NextApiRequest, NextApiResponse } from "next";

const handler = async (req: NextApiRequest, res: NextApiResponse) => {
	if (req.method !== "GET") return res.status(405);
	const [url, state] = await githubAuth.getAuthorizationUrl();
	const stateCookie = serializeCookie("github_oauth_state", state, {
		httpOnly: true,
		secure: process.env.NODE_ENV === "production",
		path: "/",
		maxAge: 60 * 60
	});
	return res
		.status(302)
		.setHeader("Set-Cookie", stateCookie)
		.setHeader("Location", url.toString())
		.end();
};

export default handler;

Validate callback#

Create pages/api/login/github/callback.ts and handle GET requests.

When the user authenticates with GitHub, GitHub will redirect back the user to your site with a code and a state. This state should be checked with the one stored as a cookie, and if valid, validate the code with GithubProvider.validateCallback(). This will return GithubUserAuth if the code is valid, or throw an error if not.

After successfully creating a user, we’ll create a new session with Auth.createSession() and store it as a cookie with AuthRequest.setSession(). AuthRequest can be created by calling Auth.handleRequest() with IncomingMessage and OutgoingMessage.

// pages/api/login/github/callback.ts
import { auth, githubAuth } from "@/auth/lucia";
import { OAuthRequestError } from "@lucia-auth/oauth";
import { parseCookie } from "lucia/utils";

import type { NextApiRequest, NextApiResponse } from "next";

const handler = async (req: NextApiRequest, res: NextApiResponse) => {
	if (req.method !== "GET") return res.status(405);
	const cookies = parseCookie(req.headers.cookie ?? "");
	const storedState = cookies.github_oauth_state;
	const state = req.query.state;
	const code = req.query.code;
	// validate state
	if (
		!storedState ||
		!state ||
		storedState !== state ||
		typeof code !== "string"
	) {
		return res.status(400).end();
	}
	try {
		const { getExistingUser, githubUser, createUser } =
			await githubAuth.validateCallback(code);

		const getUser = async () => {
			const existingUser = await getExistingUser();
			if (existingUser) return existingUser;
			const user = await createUser({
				attributes: {
					username: githubUser.login
				}
			});
			return user;
		};

		const user = await getUser();
		const session = await auth.createSession({
			userId: user.userId,
			attributes: {}
		});
		const authRequest = auth.handleRequest({ req, res });
		authRequest.setSession(session);
		return res.status(302).setHeader("Location", "/").end(); // redirect to profile page
	} catch (e) {
		if (e instanceof OAuthRequestError) {
			// invalid code
			return res.status(400).end();
		}
		return res.status(500).end();
	}
};

export default handler;

Authenticate user with Lucia#

You can check if the user has already registered with your app by checking GithubUserAuth.getExistingUser. Internally, this is done by checking if a key with the GitHub user id already exists.

If they’re a new user, you can create a new Lucia user (and key) with GithubUserAuth.createUser(). The type for attributes property is Lucia.DatabaseUserAttributes, which we added username to previously. You can access the GitHub user data with GithubUserAuth.githubUser, as well as the access tokens with GithubUserAuth.githubTokens.

const { getExistingUser, githubUser, createUser } =
	await githubAuth.validateCallback(code);

const getUser = async () => {
	const existingUser = await getExistingUser();
	if (existingUser) return existingUser;
	const user = await createUser({
		attributes: {
			username: githubUser.login
		}
	});
	return user;
};

const user = await getUser();

Redirect authenticated users#

Authenticated users should be redirected to the profile page whenever they try to access the sign in page. You can validate requests by creating by calling AuthRequest.validate(). This method returns a Session if the user is authenticated or null if not.

Since Request is not available in pages, set it to null. This should only be done for GET requests.

// app/login/page.tsx
import { auth } from "@/auth/lucia";
import { cookies } from "next/headers";
import { redirect } from "next/navigation";

const Page = async () => {
	const authRequest = auth.handleRequest("GET", context);
	const session = await authRequest.validate();
	if (session) redirect("/");
	return (
		<>
			<h1>Sign in</h1>
			<a href="/login/github">Sign in with GitHub</a>
		</>
	);
};

export default Page;

Profile page#

Create pages/index.tsx. This page will show some basic user info and include a logout button.

Unauthenticated users should be redirected to the login page. The user object is available in Session.user, and you’ll see that User.githubUsername exists because we defined it in first step with getUserAttributes() configuration.

// pages/index.tsx
import { auth } from "@/auth/lucia";
import { useRouter } from "next/router";

import type {
	GetServerSidePropsContext,
	GetServerSidePropsResult,
	InferGetServerSidePropsType
} from "next";

export const getServerSideProps = async (
	context: GetServerSidePropsContext
): Promise<
	GetServerSidePropsResult<{
		userId: string;
		githubUsername: string;
	}>
> => {
	const authRequest = auth.handleRequest(context);
	const session = await authRequest.validate();
	if (!session) {
		return {
			redirect: {
				destination: "/login",
				permanent: false
			}
		};
	}
	return {
		props: {
			userId: session.user.userId,
			githubUsername: session.user.githubUsername
		}
	};
};

const Page = (
	props: InferGetServerSidePropsType<typeof getServerSideProps>
) => {
	const router = useRouter();
	return (
		<>
			<h1>Profile</h1>
			<p>User id: {props.userId}</p>
			<p>GitHub username: {props.githubUsername}</p>
			<form
				method="post"
				action="/api/logout"
				onSubmit={async (e) => {
					e.preventDefault();
					const response = await fetch("/api/logout", {
						method: "POST",
						redirect: "manual"
					});
					if (response.status === 0 || response.ok) {
						router.push("/login"); // redirect to login page on success
					}
				}}
			>
				<input type="submit" value="Sign out" />
			</form>
		</>
	);
};

export default Page;

Sign out users#

Create pages/api/logout.ts and handle POST requests.

When logging out users, it’s critical that you invalidate the user’s session. This can be achieved with Auth.invalidateSession(). You can delete the session cookie by overriding the existing one with a blank cookie that expires immediately. This can be created by passing null to Auth.createSessionCookie().

// pages/api/logout.ts
import { auth } from "@/auth/lucia";

import type { NextApiRequest, NextApiResponse } from "next";

const handler = async (req: NextApiRequest, res: NextApiResponse) => {
	if (req.method !== "POST") return res.status(405);
	const authRequest = auth.handleRequest({ req, res });
	// check if user is authenticated
	const session = await authRequest.validate();
	if (!session) {
		return res.status(401).json({
			error: "Unauthorized"
		});
	}
	// make sure to invalidate the current session!
	await auth.invalidateSession(session.sessionId);
	// delete session cookie
	authRequest.setSession(null);
	return res.redirect(302, "/login");
};

export default handler;