Add Binding

Skill: Add a Cloudflare Binding

Workflow

1. Edit wrangler.jsonc

Add the binding configuration. Each binding type has its own top-level key:

KV Namespace

"kv_namespaces": [
  {
    "binding": "CACHE",
    "id": "<namespace-id>"   // from: npx wrangler kv namespace create CACHE
  }
]

R2 Bucket

"r2_buckets": [
  {
    "binding": "STORAGE",
    "bucket_name": "my-bucket"  // from: npx wrangler r2 bucket create my-bucket
  }
]

D1 Database

"d1_databases": [
  {
    "binding": "DB",
    "database_name": "my-db",
    "database_id": "<database-id>",  // from: npx wrangler d1 create my-db
    "migrations_dir": "drizzle"
  }
]

Queue (Producer)

"queues": {
  "producers": [
    {
      "binding": "MY_QUEUE",
      "queue": "my-queue-name"
    }
  ]
}

Secret

Secrets are NOT declared in wrangler.jsonc. They are set via CLI:

npx wrangler secret put MY_SECRET          # production
# For local dev, add to .dev.vars:
# MY_SECRET="value"

Plain Variable (vars)

"vars": {
  "ENVIRONMENT": "production",
  "API_BASE_URL": "https://api.example.com"
}

2. Regenerate types

After editing wrangler.jsonc, always run:

npm run cf-typegen

This updates worker-configuration.d.ts so TypeScript knows about the new binding. For example, after adding an R2 bucket with binding STORAGE, env.STORAGE will be typed as R2Bucket.

3. Use the binding

Import env from cloudflare:workers in server-side code:

import { env } from "cloudflare:workers"

Usage patterns per binding type:

KV

// Write
await env.CACHE.put("user:123", JSON.stringify(userData), {
  expirationTtl: 3600, // seconds
})

// Read
const raw = await env.CACHE.get("user:123")
const data = raw ? JSON.parse(raw) : null

// Delete
await env.CACHE.delete("user:123")

// List keys
const list = await env.CACHE.list({ prefix: "user:" })

R2

// Upload
await env.STORAGE.put("photos/cat.jpg", fileBody, {
  httpMetadata: { contentType: "image/jpeg" },
})

// Download
const object = await env.STORAGE.get("photos/cat.jpg")
if (object) {
  const body = object.body // ReadableStream
  const contentType = object.httpMetadata?.contentType
}

// Delete
await env.STORAGE.delete("photos/cat.jpg")

// List
const listed = await env.STORAGE.list({ prefix: "photos/", limit: 100 })

D1 (raw, without Drizzle)

const { results } = await env.DB.prepare(
  "SELECT * FROM users WHERE id = ?"
).bind(userId).all()

But prefer the Drizzle wrapper (import { db } from "@/db") for D1.

Queue

await env.MY_QUEUE.send({ type: "email", to: "user@example.com" })

// Send batch
await env.MY_QUEUE.sendBatch([
  { body: { type: "email", to: "a@example.com" } },
  { body: { type: "email", to: "b@example.com" } },
])

4. Create the resource (production)

For new projects, the resource must be created in Cloudflare before deploying:

npx wrangler kv namespace create CACHE
npx wrangler r2 bucket create my-bucket
npx wrangler d1 create my-db

Copy the printed IDs into wrangler.jsonc.

For local dev, most bindings work automatically with the Cloudflare Vite plugin -- no remote resource needed. R2 and KV use local persistence in .wrangler/state/.

Reference examples in this template

• D1: wrangler.jsonc d1_databases + src/db/index.ts
• R2: wrangler.jsonc r2_buckets + src/routes/api/files.ts

Common mistakes to avoid

• Wrong: Importing env in a client component. cloudflare:workers is server-only.
• Wrong: Passing env as a function argument. Import it where needed.
• Wrong: Using process.env for bindings. That's Node.js.
• Wrong: Forgetting to run npm run cf-typegen after editing wrangler.jsonc. TypeScript won't know about the new binding.
• Wrong: Putting secrets in wrangler.jsonc. Use wrangler secret put for production and .dev.vars for local dev.