Getting started in Fastify

Install Lucia using your package manager of your choice.

npm i lucia
pnpm add lucia
yarn add lucia

ESM#

Lucia can only be used in ESM projects. Configure your package.json and tsconfig.json accordingly.

// package.json
{
	"type": "module"
	// ...
}

// tsconfig.json
{
	"compilerOptions": {
		"module": "ESNext", // "ES2022" etc
		"moduleResolution": "NodeNext" // "Node", "Node16"
		// ...
	}
	// ...
}

Initialize Lucia#

Import lucia() from lucia and initialize it. Export auth and its type as Auth. Make sure to pass the fastify() middleware We also need to provide an adapter but since it’ll be specific to the database you’re using, we’ll cover that later.

// lucia.ts
import { lucia } from "lucia";
import { fastify } from "lucia/middleware";

// expect error (see next section)
export const auth = lucia({
	env: "DEV", // "PROD" if deployed to HTTPS
	middleware: fastify()
});

export type Auth = typeof auth;

Setup your database#

Lucia uses adapters to connect to your database. We provide official adapters for a wide range of database options, but you can always create your own. The schema and usage are described in each adapter’s documentation. The example below is for the Prisma adapter.

import { lucia } from "lucia";
import { fastify } from "lucia/middleware";
import { prisma } from "@lucia-auth/adapter-prisma";
import { PrismaClient } from "@prisma/client";

const client = new PrismaClient();

const auth = lucia({
	env: "DEV", // "PROD" if deployed to HTTPS
	middleware: fastify(),
	adapter: prisma(client)
});

Adapters for database drivers and ORMs#

• better-sqlite3: SQLite
• libSQL: libSQL (Turso)
• Mongoose: MongoDB
• mysql2: MySQL
• pg: PostgreSQL (including @neondatabase/serverless, @vercel/postgres)
• postgres: PostgreSQL
• Prisma: MongoDB, MySQL, PostgreSQL, SQLite
• Redis: Redis
• Unstorage: Azure, Cloudflare KV, Memory, MongoDB, Planetscale, Redis, Vercel KV

Provider specific adapters#

• Cloudflare D1
• PlanetScale serverless
• Upstash Redis

Using query builders#

• Drizzle ORM
• Kysely

Set up types#

Create a .d.ts file in your project root and declare a Lucia namespace. The import path for Auth is where you initialized lucia().

// app.d.ts
/// <reference types="lucia" />
declare namespace Lucia {
	type Auth = import("./lucia.js").Auth;
	type DatabaseUserAttributes = {};
	type DatabaseSessionAttributes = {};
}

Polyfill#

If you’re using Node.js version 18 or below, you need to polyfill the Web Crypto API.

import { lucia } from "lucia";
import "lucia/polyfill/node";

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

Optionally, instead of doing a side-effect import, add the --experimental-global-webcrypto flag when running fastify.

{
	"scripts": {
		"start": "NODE_OPTIONS=--experimental-global-webcrypto fastify start -l info app.js",
		"dev": "NODE_OPTIONS=--experimental-global-webcrypto npm run build && fastify start -w -l info -P app.js"
		// ...
	}
	// ...
}

Next steps#

You can learn all the concepts and general APIs of Lucia by reading the Basics section in the docs. If you prefer writing code immediately, check out the Starter guides page or the examples repository.

Remember to check out the Guidebook for tutorials and guides! If you have any questions, join our Discord server!