Auth Clerk

          
            ## Astro Authentication Guidelines (Focus: Clerk)

1.  Overview: Astro does not have built-in authentication. Integration with third-party services is required. Popular options include Clerk, Auth.js, Lucia, and Better Auth. This guide focuses on Clerk.

2.  Clerk Integration (`@clerk/astro`):

    - Purpose: Provides a complete suite for user authentication and management, including pre-built UI components, APIs, and admin dashboards. Offers an official SDK for Astro.
    - Installation:
      - Install the official Clerk SDK:
        ```bash
        npm install @clerk/astro
        # or pnpm add @clerk/astro / yarn add @clerk/astro
        ```
    - Configuration:
      - Requires a Clerk account and project setup.
      - Follow the official Clerk Astro Quickstart guide for detailed instructions. This typically involves:
        - Setting up environment variables with your Clerk API keys (Publishable Key, Secret Key).
        - Configuring Clerk middleware in `src/middleware.ts`.
    - Client-Side Usage (UI Components):
      - Import Clerk components from `@clerk/astro/components` into your `.astro` files.
      - Use components like `<SignedIn>`, `<SignedOut>`, `<UserButton>`, and `<SignInButton>` to conditionally render UI elements based on the user's authentication status.
        ```astro
        ---
        import Layout from 'src/layouts/Base.astro';
        import { SignedIn, SignedOut, UserButton, SignInButton } from '@clerk/astro/components';
        ---
        <Layout>
          <header>
            <SignedIn>
              <UserButton afterSignOutUrl="/" />
            </SignedIn>
            <SignedOut>
              <SignInButton />
            </SignedOut>
          </header>
          <main>
            <!-- Page Content -->
          </main>
        </Layout>
        ```
    - Server-Side Usage (Middleware for Route Protection):

      - Import `clerkMiddleware` and `createRouteMatcher` from `@clerk/astro/server` in `src/middleware.ts`.
      - Define which routes require authentication using `createRouteMatcher`.
      - Use `clerkMiddleware` to check the user's auth state (`auth().userId`) and redirect unauthenticated users attempting to access protected routes (e.g., using `auth().redirectToSignIn()`).

        ```typescript
        // src/middleware.ts
        import {
          clerkMiddleware,
          createRouteMatcher,
        } from "@clerk/astro/server";

        // Define protected routes
        const isProtectedRoute = createRouteMatcher([
          "/dashboard(.*)", // Protects /dashboard and sub-routes
          "/settings",
        ]);

        export const onRequest = clerkMiddleware((auth, context) => {
          // If the route is protected and the user is not logged in...
          if (isProtectedRoute(context.request) && !auth().userId) {
            // Redirect them to the sign-in page
            return auth().redirectToSignIn({
              returnBackUrl: context.request.url,
            });
          }
        });
        ```

3.  Other Options (Briefly):

    - Auth.js (`auth-astro`): Community adapter for the popular Auth.js library. Requires configuration with providers.
    - Lucia: Session-based authentication library; requires setting up APIs and middleware manually.
    - Better Auth: Framework-agnostic library with its own set of helpers and configuration.

4.  Key Considerations for Any Auth Solution:
    - SSR Required: Authentication typically requires Server-Side Rendering (SSR) enabled via an Astro adapter (e.g., Node, Vercel, Netlify, Cloudflare).
    - Middleware: Often used for session management and protecting routes server-side.
    - Environment Variables: API keys and secrets must be stored securely using environment variables (`.env`).

Reference: [Astro Authentication Guide](mdc:https:/docs.astro.build/en/guides/authentication), [Clerk Astro Quickstart](mdc:https:/clerk.com/docs/quickstarts/astro)