/eas-hosting

name: eas-hosting
description: EAS service (paid). Deploy Expo websites and Expo Router API routes to EAS Hosting - export the web bundle, run eas deploy for production and PR preview URLs, manage environment secrets and custom domains, and work within the Cloudflare Workers runtime. Also covers authoring API routes (+api.ts handlers, HTTP methods, request handling, CORS). Use when deploying an Expo web app or API routes, setting up EAS Hosting, or configuring hosting environments and domains. Not for native builds or store releases - use the eas-app-stores skill for those.
version: 1.0.0
license: MIT

EAS Hosting

> **EAS service - costs apply.** EAS Hosting is a paid Expo Application Services product with free-tier limits; production deploys use your plan's request and bandwidth allowance. See https://expo.dev/pricing. Authoring API routes and exporting the web bundle are free and open source, and you can self-host the exported server output instead of EAS Hosting.

EAS Hosting deploys your Expo **web app and API routes** to Expo's managed edge (Cloudflare Workers). Export the web bundle with `npx expo export -p web` and ship it with `eas deploy` - the same command deploys any Expo Router API routes bundled alongside it. This skill covers deploying a website, authoring API routes, and the hosting runtime; see the Deployment section below for the deploy workflow.

When to Use API Routes

Use API routes when you need:

• **Server-side secrets** — API keys, database credentials, or tokens that must never reach the client
• **Database operations** — Direct database queries that shouldn't be exposed
• **Third-party API proxies** — Hide API keys when calling external services (OpenAI, Stripe, etc.)
• **Server-side validation** — Validate data before database writes
• **Webhook endpoints** — Receive callbacks from services like Stripe or GitHub
• **Rate limiting** — Control access at the server level
• **Heavy computation** — Offload processing that would be slow on mobile

When NOT to Use API Routes

Avoid API routes when:

• **Data is already public** — Use direct fetch to public APIs instead
• **No secrets required** — Static data or client-safe operations
• **Real-time updates needed** — Use WebSockets or services like Supabase Realtime
• **Simple CRUD** — Consider Firebase, Supabase, or Convex for managed backends
• **File uploads** — Use direct-to-storage uploads (S3 presigned URLs, Cloudflare R2)
• **Authentication only** — Use Clerk, Auth0, or Firebase Auth instead

File Structure

API routes live in the `app` directory with `+api.ts` suffix:

app/
  api/
    hello+api.ts          → GET /api/hello
    users+api.ts          → /api/users
    users/[id]+api.ts     → /api/users/:id
  (tabs)/
    index.tsx

Basic API Route

// app/api/hello+api.ts
export function GET(request: Request) {
  return Response.json({ message: "Hello from Expo!" });
}

HTTP Methods

Export named functions for each HTTP method:

// app/api/items+api.ts
export function GET(request: Request) {
  return Response.json({ items: [] });
}

export async function POST(request: Request) {
  const body = await request.json();
  return Response.json({ created: body }, { status: 201 });
}

export async function PUT(request: Request) {
  const body = await request.json();
  return Response.json({ updated: body });
}

export async function DELETE(request: Request) {
  return new Response(null, { status: 204 });
}

Dynamic Routes

// app/api/users/[id]+api.ts
export function GET(request: Request, { id }: { id: string }) {
  return Response.json({ userId: id });
}

Request Handling

Query Parameters

export function GET(request: Request) {
  const url = new URL(request.url);
  const page = url.searchParams.get("page") ?? "1";
  const limit = url.searchParams.get("limit") ?? "10";

  return Response.json({ page, limit });
}

Headers

export function GET(request: Request) {
  const auth = request.headers.get("Authorization");

  if (!auth) {
    return Response.json({ error: "Unauthorized" }, { status: 401 });
  }

  return Response.json({ authenticated: true });
}

JSON Body

export async function POST(request: Request) {
  const { email, password } = await request.json();

  if (!email || !password) {
    return Response.json({ error: "Missing fields" }, { status: 400 });
  }

  return Response.json({ success: true });
}

Environment Variables

Use `process.env` for server-side secrets:

// app/api/ai+api.ts
export async function POST(request: Request) {
  const { prompt } = await request.json();

  const response = await fetch("https://api.openai.com/v1/chat/completions", {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      Authorization: `Bearer ${process.env.OPENAI_API_KEY}`,
    },
    body: JSON.stringify({
      model: "gpt-4",
      messages: [{ role: "user", content: prompt }],
    }),
  });

  const data = await response.json();
  return Response.json(data);
}

Set environment variables:

• **Local**: Create `.env` file (never commit)
• **EAS Hosting**: Use `eas env:create` or Expo dashboard

CORS Headers

Add CORS for web clients:

const corsHeaders = {
  "Access-Control-Allow-Origin": "*",
  "Access-Control-Allow-Methods": "GET, POST, PUT, DELETE, OPTIONS",
  "Access-Control-Allow-Headers": "Content-Type, Authorization",
};

export function OPTIONS() {
  return new Response(null, { headers: corsHeaders });
}

export function GET() {
  return Response.json({ data: "value" }, { headers: corsHeaders });
}

Error Handling

export async function POST(request: Request) {
  try {
    const body = await request.json();
    // Process...
    return Response.json({ success: true });
  } catch (error) {
    console.error("API error:", error);
    return Response.json({ error: "Internal server error" }, { status: 500 });
  }
}

Testing Locally

Start