cloudflare-nextjs

What this skill does

# Cloudflare Next.js Deployment Skill

Deploy Next.js applications to Cloudflare Workers using the OpenNext Cloudflare adapter for production-ready serverless Next.js hosting.

## When to Load References

Load additional reference files based on your specific task:

- **`references/error-catalog-extended.md`** - Load when encountering ANY error during setup, build, or deployment. Contains complete catalog of 11+ documented issues with root causes, solutions, and official sources.

- **`references/service-integration-patterns.md`** - Load when integrating Cloudflare services (D1, R2, KV, Workers AI) with Next.js. Contains complete patterns for database queries, file uploads, caching, and AI inference.

- **`references/troubleshooting.md`** - Load for general troubleshooting and debugging guidance beyond the error catalog.

- **`references/feature-support.md`** - Load when checking if a specific Next.js feature is supported on Cloudflare Workers (e.g., "Can I use Server Actions?", "Does ISR work?").

- **`references/database-client-example.ts`** - Load when integrating external database clients (Drizzle, Prisma, PostgreSQL, MySQL) with proper request-scoping patterns required by Workers.

- **`references/open-next.config.ts`** - Load when configuring caching behavior, image optimization, or custom OpenNext settings.

- **`references/package.json`** - Load when setting up a new project or migrating an existing Next.js application to Cloudflare Workers.

- **`references/wrangler.jsonc`** - Load when configuring Worker settings, compatibility flags, environment bindings (D1, R2, KV, AI), or deployment options.

## Use This Skill When

- Deploying Next.js applications (App Router or Pages Router) to Cloudflare Workers
- Need server-side rendering (SSR), static site generation (SSG), or incremental static regeneration (ISR) on Cloudflare
- Migrating existing Next.js apps from Vercel, AWS, or other platforms to Cloudflare
- Building full-stack Next.js applications with Cloudflare services (D1, R2, KV, Workers AI)
- Need React Server Components, Server Actions, or Next.js middleware on Workers
- Want global edge deployment with Cloudflare's network

## Key Differences from Standard Next.js

**OpenNext Adapter** transforms Next.js builds for Workers. **Critical requirements**:
- Node.js runtime (NOT Edge) via `nodejs_compat` flag
- Request-scoped database clients (global clients fail)
- Worker size limits: 3 MiB (free) / 10 MiB (paid)
- Dual testing: `next dev` for speed, `preview` for production-like validation

## Setup Patterns

### New Project Setup

Use Cloudflare's `create-cloudflare` (C3) CLI to scaffold a new Next.js project pre-configured for Workers:

```bash
npm create cloudflare@latest -- my-next-app --framework=next
```

**What this does**:
1. Runs Next.js official setup tool (`create-next-app`)
2. Installs `@opennextjs/cloudflare` adapter
3. Creates `wrangler.jsonc` with correct configuration
4. Creates `open-next.config.ts` for caching configuration
5. Adds deployment scripts to `package.json`
6. Optionally deploys immediately to Cloudflare

**Development workflow**:
```bash
npm run dev      # Next.js dev server (fast reloads)
npm run preview  # Test in workerd runtime (production-like)
npm run deploy   # Build and deploy to Cloudflare
```

### Existing Project Migration

To add the OpenNext adapter to an existing Next.js application:

#### 1. Install the adapter

```bash
bun add -d @opennextjs/cloudflare
```

##### Secure Installation

Adapter packages handle production traffic — pin exact versions and audit before upgrading. Follow supply chain security best practices:

- **Block post-install scripts** — `npm config set ignore-scripts true` (or Bun: disabled by default)
- **Cooldown period** — Wait 7 days for new package versions to be vetted by the community
- **Audit before installing** — Run `socket package score npm <pkg>` or use `socket npm install <pkg>` to check packages

Load the `dependency-upgrade` skill for full security configuration including Socket CLI integration, cooldown setup, lockfile validation, and CI enforcement.

#### 2. Create wrangler.jsonc

```jsonc
{
  "name": "my-next-app",
  "compatibility_date": "2025-05-05",
  "compatibility_flags": ["nodejs_compat"]
}
```

**Critical configuration**:
- `compatibility_date`: **Minimum `2025-05-05`** (for FinalizationRegistry support)
- `compatibility_flags`: **Must include `nodejs_compat`** (for Node.js runtime)

#### 3. Create open-next.config.ts

```typescript
import { defineCloudflareConfig } from "@opennextjs/cloudflare";

export default defineCloudflareConfig({
  // Caching configuration (optional)
  // See: https://opennext.js.org/cloudflare/caching
});
```

#### 4. Update package.json scripts

```json
{
  "scripts": {
    "dev": "next dev",
    "build": "next build",
    "preview": "opennextjs-cloudflare build && opennextjs-cloudflare preview",
    "deploy": "opennextjs-cloudflare build && opennextjs-cloudflare deploy",
    "cf-typegen": "wrangler types --env-interface CloudflareEnv cloudflare-env.d.ts"
  }
}
```

**Script purposes**:
- `dev`: Next.js development server (fast iteration)
- `preview`: Build + run in workerd runtime (test before deploy)
- `deploy`: Build + deploy to Cloudflare
- `cf-typegen`: Generate TypeScript types for Cloudflare bindings

#### 5. Ensure Node.js runtime (not Edge)

Remove Edge runtime exports from your app:

```typescript
// ❌ REMOVE THIS (Edge runtime not supported)
export const runtime = "edge";

// ✅ Use Node.js runtime (default)
// No export needed - Node.js is default
```

## Development Workflow

**Dual Testing Required**:
- `npm run dev` - Fast iteration (Next.js dev server)
- `npm run preview` - Production-like testing (workerd runtime, **REQUIRED before deploy**)
- `npm run deploy` - Build and deploy

**Critical**: Always test `preview` before deploying to catch Workers-specific runtime issues

## Critical Configuration

**wrangler.jsonc** minimum requirements:
```jsonc
{
  "compatibility_date": "2025-05-05",  // Minimum for FinalizationRegistry
  "compatibility_flags": ["nodejs_compat"]  // Required for Node.js runtime
}
```

**Cloudflare Bindings**: Add D1, R2, KV, or AI bindings in `wrangler.jsonc`, access via `process.env` (see "Cloudflare Services Integration" section for complete patterns)

**Package Exports** (if needed): Create `.env` with `WRANGLER_BUILD_PLATFORM="node"` to prioritize Node.js exports

## Top 5 Critical Errors

These are the most common deployment-blocking errors. **For the complete catalog of 11+ errors, load `references/error-catalog-extended.md`**.

### 1. Worker Size Limit Exceeded

**Error**: `"Your Worker exceeded the size limit of 3 MiB"` (Free) or `"10 MiB"` (Paid)

**Quick Fix**: Upgrade plan, analyze bundle with `bunx opennextjs-cloudflare build` → check `.open-next/server-functions/default/handler.mjs.meta.json`, remove unused dependencies, or use dynamic imports.

**Source**: https://opennext.js.org/cloudflare/troubleshooting#worker-size-limits

---

### 2. Cannot Perform I/O on Behalf of Different Request

**Error**: `"Cannot perform I/O on behalf of a different request"`

**Cause**: Global database client reused across requests (Workers limitation)

**Quick Fix**: Create database clients INSIDE request handlers, never globally. Or use Cloudflare D1 which is designed for Workers.

```typescript
// ❌ WRONG: Global client
const pool = new Pool({ connectionString: process.env.DATABASE_URL });

// ✅ CORRECT: Request-scoped
export async function GET() {
  const pool = new Pool({ connectionString: process.env.DATABASE_URL });
  // ... use pool
  await pool.end();
}
```

**Source**: https://opennext.js.org/cloudflare/troubleshooting#cannot-perform-io-on-behalf-of-a-different-request

---

### 3. NPM Package Import Failures

**Error**: `"Could not resolve '<package>'"`

**Quick Fix**: Enable `nodejs_compat` flag in wrangler.jsonc, and/or create `.env` with `WRANGLER_BUILD_PLATFORM="node"`.

**Source