Sessions & Middleware in Astro
From the Astro cheat sheet · Modern Astro (Server Islands, Actions, Sessions) · verified Jul 2026
Sessions & Middleware
Built-in sessions (5.1+) and the middleware request/response chain
typescript
// src/middleware.ts
import { defineMiddleware } from 'astro:middleware'
export const onRequest = defineMiddleware(async (context, next) => {
// Read or write per-request session data
const cart = await context.session?.get('cart') ?? []
context.locals.cart = cart
const res = await next()
return res
})
// astro.config.mjs: sessions are stable in Astro 6+ (no experimental flag)
import { defineConfig, sessionDrivers } from 'astro/config'
export default defineConfig({
session: {
driver: sessionDrivers.redis({ url: process.env.REDIS_URL }),
},
})💡 Middleware runs on every request — set locals there, read in pages
⚡ sequence() composes multiple middlewares cleanly in render order
📌 Sessions are stable in Astro 6+ (no experimental flag); set driver via sessionDrivers, or let the Node/Netlify/Cloudflare adapter auto-configure one
🎯 Always declare App.Locals and App.SessionData in env.d.ts for full type safety
middlewaresessionsauth