From cloudflare-workers
Guides migration from AWS Lambda, Vercel, Express, and Node.js to Cloudflare Workers with decision trees, error fixes, and code patterns.
npx claudepluginhub secondsky/claude-skills --plugin cloudflare-workersThis skill uses the workspace's default tool permissions.
Migrate existing applications to Cloudflare Workers from various platforms.
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Migrate existing applications to Cloudflare Workers from various platforms.
What are you migrating from?
├── AWS Lambda
│ └── Node.js handler? → Lambda adapter pattern
│ └── Python? → Consider Python Workers
│ └── Container/custom runtime? → May need rewrite
├── Vercel/Next.js
│ └── API routes? → Minimal changes with adapter
│ └── Full Next.js app? → Use OpenNext adapter
│ └── Middleware? → Direct Workers equivalent
├── Express/Node.js
│ └── Simple API? → Hono (similar API)
│ └── Complex middleware? → Gradual migration
│ └── Heavy node: usage? → Compatibility layer
└── Other Edge (Deno Deploy, Fastly)
└── Standard Web APIs? → Minimal changes
└── Platform-specific? → Targeted rewrites
| Feature | Workers | Lambda | Vercel | Express |
|---|---|---|---|---|
| Cold Start | ~0ms | 100-500ms | 10-100ms | N/A |
| CPU Limit | 50ms/10ms | 15 min | 10s | None |
| Memory | 128MB | 10GB | 1GB | System |
| Max Response | 6MB (stream unlimited) | 6MB | 4.5MB | None |
| Global Edge | 300+ PoPs | Regional | ~20 PoPs | Manual |
| Node.js APIs | Partial | Full | Full | Full |
| Error | From | Cause | Solution |
|---|---|---|---|
fs is not defined | Lambda/Express | File system access | Use KV/R2 for storage |
Buffer is not defined | Node.js | Node.js globals | Import from node:buffer |
process.env undefined | All | Env access pattern | Use env parameter |
setTimeout not returning | Lambda | Async patterns | Use ctx.waitUntil() |
require() not found | Express | CommonJS | Convert to ESM imports |
Exceeded CPU time | All | Long computation | Chunk or use DO |
body already consumed | Express | Request body | Clone before read |
Headers not iterable | Lambda | Headers API | Use Headers constructor |
crypto.randomBytes | Node.js | Node crypto | Use crypto.getRandomValues |
Cannot find module | All | Missing polyfill | Check Workers compatibility |
// Before: AWS Lambda
export const handler = async (event, context) => {
const body = JSON.parse(event.body);
return {
statusCode: 200,
body: JSON.stringify({ message: 'Hello' }),
};
};
// After: Cloudflare Workers
export default {
async fetch(request: Request, env: Env): Promise<Response> {
const body = await request.json();
return Response.json({ message: 'Hello' });
},
};
// Before: Express
app.use((req, res, next) => {
if (!req.headers.authorization) {
return res.status(401).json({ error: 'Unauthorized' });
}
next();
});
// After: Hono Middleware
app.use('*', async (c, next) => {
if (!c.req.header('Authorization')) {
return c.json({ error: 'Unauthorized' }, 401);
}
await next();
});
// Before: Node.js
const apiKey = process.env.API_KEY;
// After: Workers
export default {
async fetch(request: Request, env: Env): Promise<Response> {
const apiKey = env.API_KEY;
// ...
},
};
Workers support many Node.js APIs via compatibility flags:
// wrangler.jsonc
{
"compatibility_flags": ["nodejs_compat_v2"],
"compatibility_date": "2024-12-01"
}
Supported with nodejs_compat_v2:
crypto (most methods)buffer (Buffer class)util (promisify, types)stream (Readable, Writable)events (EventEmitter)path (all methods)string_decoderassertNot Supported (need alternatives):
fs → Use R2/KVchild_process → Not possiblecluster → Not applicabledgram → Not supportednet → Use fetch/WebSockettls → Handled by platform| Reference | Load When |
|---|---|
references/lambda-migration.md | Migrating AWS Lambda functions |
references/vercel-migration.md | Migrating from Vercel/Next.js |
references/express-migration.md | Migrating Express/Node.js apps |
references/node-compatibility.md | Node.js API compatibility issues |
workers-runtime-apis - Available APIs in Workersworkers-performance - Optimization techniquescloudflare-worker-base - Basic Workers setup