dotfiles/dot_agents/skills/cloudflare/references/bindings/README.md

Cloudflare Bindings Skill Reference

Expert guidance on Cloudflare Workers Bindings - the runtime APIs that connect Workers to Cloudflare platform resources.

What Are Bindings?

Bindings are how Workers access Cloudflare resources (storage, compute, services) via the env object. They're configured in wrangler.jsonc, type-safe via TypeScript, and zero-overhead at runtime.

Reading Order

1. This file - Binding catalog and selection guide
2. api.md - TypeScript types and env access patterns
3. configuration.md - Complete wrangler.jsonc examples
4. patterns.md - Best practices and common patterns
5. gotchas.md - Critical pitfalls and troubleshooting

Binding Catalog

Storage Bindings

Binding	Use Case	Access Pattern
KV	Key-value cache, CDN-backed reads	env.MY_KV.get(key)
R2	Object storage (S3-compatible)	env.MY_BUCKET.get(key)
D1	SQL database (SQLite)	env.DB.prepare(sql).all()
Durable Objects	Coordination, real-time state	env.MY_DO.get(id)
Vectorize	Vector embeddings search	env.VECTORIZE.query(vector)
Queues	Async message processing	env.MY_QUEUE.send(msg)

Compute Bindings

Binding	Use Case	Access Pattern
Service	Worker-to-Worker RPC	env.MY_SERVICE.fetch(req)
Workers AI	LLM inference	env.AI.run(model, input)
Browser Rendering	Headless Chrome	env.BROWSER.fetch(url)

Platform Bindings

Binding	Use Case	Access Pattern
Analytics Engine	Custom metrics	env.ANALYTICS.writeDataPoint(data)
mTLS	Client certificates	env.MY_CERT (string)
Hyperdrive	Database pooling	env.HYPERDRIVE.connectionString
Rate Limiting	Request throttling	env.RATE_LIMITER.limit(id)
Workflows	Long-running workflows	env.MY_WORKFLOW.create()

Configuration Bindings

Binding	Use Case	Access Pattern
Environment Variables	Non-sensitive config	env.API_URL (string)
Secrets	Sensitive values	env.API_KEY (string)
Text/Data Blobs	Static files	env.MY_BLOB (string)
WASM	WebAssembly modules	env.MY_WASM (WebAssembly.Module)

Quick Selection Guide

Need persistent storage?

• Key-value < 25MB → KV
• Files/objects → R2
• Relational data → D1
• Real-time coordination → Durable Objects

Need AI/compute?

• LLM inference → Workers AI
• Scraping/PDFs → Browser Rendering
• Call another Worker → Service binding

Need async processing?

• Background jobs → Queues

Need config?

• Public values → Environment Variables
• Secrets → Secrets (never commit)

Quick Start

1. Add binding to wrangler.jsonc:

{
  "kv_namespaces": [
    { "binding": "MY_KV", "id": "your-kv-id" }
  ]
}

2. Generate types:

npx wrangler types

3. Access in Worker:

export default {
  async fetch(request, env, ctx) {
    await env.MY_KV.put('key', 'value');
    return new Response('OK');
  }
}

Type Safety

Bindings are fully typed via wrangler types. See api.md for details.

Limits

• 64 bindings max per Worker (all types combined)
• See gotchas.md for per-binding limits

Key Concepts

Zero-overhead access: Bindings compiled into Worker, no network calls to access Type-safe: Full TypeScript support via wrangler types Per-environment: Different IDs for dev/staging/production Secrets vs Vars: Secrets encrypted at rest, never in config files

See Also

• Cloudflare Docs: Bindings
• Wrangler Configuration