Elysia

This guide shows how to integrate gau with an Elysia server.

1. Follow the basic setup

   Complete the Getting Started guide for installation, environment variables, and adding at least one OAuth provider.

2. Create your auth configuration

   src/auth.ts

   import process from 'node:process'
   import { MemoryAdapter } from '@rttnd/gau/adapters/memory'
   import { createAuth } from '@rttnd/gau/core'
   import { GitHub } from '@rttnd/gau/oauth'
   
   export const auth = createAuth({
     adapter: MemoryAdapter(),
     providers: [
       GitHub({
         clientId: process.env.AUTH_GITHUB_ID!,
         clientSecret: process.env.AUTH_GITHUB_SECRET!,
       }),
     ],
     jwt: {
       secret: process.env.AUTH_SECRET!,
     },
     // When frontend runs on a different origin, set the trusted hosts, example:
     // trustHosts: ['http://localhost:5173'],
   })
   
   export type Auth = typeof auth

   Note

   gau handles CORS and CSRF. For cross-origin setups, configure trustHosts in createAuth.

3. Mount the fetch handler

   createHandler(auth) returns a standard Fetch handler (req: Request) => Promise<Response>. You can mount it directly on an Elysia app using .mount().

   src/index.ts

   import { createHandler } from '@rttnd/gau/core'
   import { Elysia } from 'elysia'
   import { auth } from './auth'
   
   const handler = createHandler(auth)
   
   const app = new Elysia()
     .mount(handler)
     .get('/', () => 'OK')
     .listen(3000)
   
   console.log(`🦊 Elysia is running at ${app.server?.hostname}:${app.server?.port}`)

4. Configure CORS

   You are probably not using Elysia exclusively for auth. In that case, disable gau’s CORS handling by setting cors: false in createAuth. Then, configure CORS for your whole app using Elysia’s CORS plugin.

   src/index.ts

   import { cors } from '@elysiajs/cors'
   import { createHandler } from '@rttnd/gau/core'
   import { Elysia } from 'elysia'
   import { auth } from './auth'
   
   const handler = createHandler(auth)
   
   const app = new Elysia()
     .mount(handler)
     .use(cors())
     .get('/', () => 'OK')
     .listen(3000)
   
   console.log(`🦊 Elysia is running at ${app.server?.hostname}:${app.server?.port}`)

5. Try it

   Look at the Elysia Example.

6. File Structure (example)

   • Directorysrc

     • auth.ts
     • index.ts
   • package.json