Agent Skills: Cloudflare R2

Cloudflare R2

R2 is S3-compatible object storage with zero egress fees. Access via Workers Binding API or S3 API.

Quick Start

npx wrangler r2 bucket create my-bucket

// wrangler.jsonc
{
  "r2_buckets": [{ "binding": "MY_BUCKET", "bucket_name": "my-bucket" }]
}

export interface Env {
  MY_BUCKET: R2Bucket;
}

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const key = new URL(request.url).pathname.slice(1);

    if (request.method === "PUT") {
      await env.MY_BUCKET.put(key, request.body);
      return new Response("Uploaded", { status: 201 });
    }

    if (request.method === "GET") {
      const object = await env.MY_BUCKET.get(key);
      if (!object) return new Response("Not Found", { status: 404 });
      const headers = new Headers();
      object.writeHttpMetadata(headers);
      headers.set("etag", object.httpEtag);
      return new Response(object.body, { headers });
    }
    return new Response("Method Not Allowed", { status: 405 });
  },
};

Binding Configuration

{
  "r2_buckets": [
    {
      "binding": "MY_BUCKET",
      "bucket_name": "my-bucket",
      "preview_bucket_name": "my-bucket-preview", // Optional: for local dev
      "jurisdiction": "eu" // Optional: GDPR
    }
  ]
}

See binding.md for details.

Workers Binding API (R2Bucket)

| Method | Description | | -------------------------------------- | ---------------------------- | | head(key) | Get metadata without body | | get(key, options?) | Get object with body | | put(key, value, options?) | Store object | | delete(key \| keys[]) | Delete up to 1000 keys | | list(options?) | List objects with pagination | | createMultipartUpload(key, options?) | Start multipart upload | | resumeMultipartUpload(key, uploadId) | Resume multipart upload |

get with range

const partial = await env.MY_BUCKET.get("large.bin", {
  range: { offset: 0, length: 1024 },
});

put with metadata

await env.MY_BUCKET.put("file.txt", "Hello!", {
  httpMetadata: { contentType: "text/plain" },
  customMetadata: { author: "Alice" },
  storageClass: "InfrequentAccess", // Optional
});

list with pagination

const listed = await env.MY_BUCKET.list({ prefix: "images/", limit: 100 });
for (const obj of listed.objects) console.log(obj.key, obj.size);
if (listed.truncated) {
  /* use listed.cursor for next page */
}

See api.md for complete reference.

R2Object / R2ObjectBody

interface R2Object {
  key: string;
  version: string;
  size: number;
  etag: string;
  httpEtag: string;
  uploaded: Date;
  httpMetadata: R2HTTPMetadata;
  customMetadata: Record<string, string>;
  storageClass: "Standard" | "InfrequentAccess";
  writeHttpMetadata(headers: Headers): void;
}

interface R2ObjectBody extends R2Object {
  body: ReadableStream;
  arrayBuffer(): Promise<ArrayBuffer>;
  text(): Promise<string>;
  json<T>(): Promise<T>;
  blob(): Promise<Blob>;
}

S3 API Compatibility

Endpoint: https://<ACCOUNT_ID>.r2.cloudflarestorage.com

import { S3Client } from "@aws-sdk/client-s3";

const S3 = new S3Client({
  region: "auto",
  endpoint: `https://${ACCOUNT_ID}.r2.cloudflarestorage.com`,
  credentials: { accessKeyId: ACCESS_KEY_ID, secretAccessKey: SECRET_ACCESS_KEY },
});

Region: Always "auto" (or "us-east-1" alias).

Presigned URLs

import { GetObjectCommand, PutObjectCommand } from "@aws-sdk/client-s3";
import { getSignedUrl } from "@aws-sdk/s3-request-presigner";

const downloadUrl = await getSignedUrl(S3, new GetObjectCommand({ Bucket: "my-bucket", Key: "file.pdf" }), { expiresIn: 3600 });

const uploadUrl = await getSignedUrl(S3, new PutObjectCommand({ Bucket: "my-bucket", Key: "file.pdf", ContentType: "application/pdf" }), { expiresIn: 3600 });

Important: Presigned URLs work only with S3 endpoint (not custom domains). Configure CORS for browser use. See presigned-urls.md.

Multipart Uploads

For objects > 100 MB.

const mpu = await env.MY_BUCKET.createMultipartUpload("large.zip");
const part1 = await mpu.uploadPart(1, chunk1); // Min 5 MiB
const part2 = await mpu.uploadPart(2, chunk2);
await mpu.complete([part1, part2]);
// or: await mpu.abort();

Resume: env.MY_BUCKET.resumeMultipartUpload(key, uploadId)

Limits: 5 MiB–5 GiB per part, 10,000 parts max, ~5 TiB max object. See multipart.md.

CORS Configuration

[
  {
    "AllowedOrigins": ["https://example.com"],
    "AllowedMethods": ["GET", "PUT"],
    "AllowedHeaders": ["Content-Type"],
    "ExposeHeaders": ["ETag"],
    "MaxAgeSeconds": 3600
  }
]

npx wrangler r2 bucket cors set my-bucket --file cors.json

Lifecycle Policies

# Delete after 90 days
npx wrangler r2 bucket lifecycle add my-bucket --id "cleanup" --expire-days 90

# Transition to Infrequent Access
npx wrangler r2 bucket lifecycle add my-bucket --id "archive" --transition-days 30 --transition-class STANDARD_IA

# With prefix
npx wrangler r2 bucket lifecycle add my-bucket --id "logs" --prefix "logs/" --expire-days 7

# Abort incomplete multipart
npx wrangler r2 bucket lifecycle add my-bucket --id "mpu" --abort-incomplete-days 1

See lifecycle.md for S3 API examples.

Storage Classes

| Class | Storage | Notes | | ---------------- | --------- | ------------------------------- | | Standard | $0.015/GB | Default | | InfrequentAccess | $0.01/GB | +$0.01/GB retrieval, 30-day min |

await env.MY_BUCKET.put("archive.zip", data, { storageClass: "InfrequentAccess" });

Event Notifications

Push to Cloudflare Queues on object changes.

npx wrangler queues create r2-events
npx wrangler r2 bucket notification create my-bucket --event-type object-create --queue r2-events

Events: object-create, object-delete

export default {
  async queue(batch: MessageBatch<R2EventMessage>, env: Env) {
    for (const msg of batch.messages) {
      console.log(`${msg.body.action}: ${msg.body.object.key}`);
      msg.ack();
    }
  },
};

Public Buckets

Custom domain (recommended)

Dashboard → Bucket → Settings → Custom Domains → Add. Enables Cache, WAF, Access.

r2.dev (dev only)

Dashboard → Bucket → Settings → Public Development URL → Enable.

Warning: r2.dev is rate-limited. Use custom domain for production.

Data Migration

Super Slurper (bulk)

Dashboard → R2 → Data Migration. Copies from S3/GCS/compatible storage. Objects > 1 TB skipped.

Sippy (incremental)

npx wrangler r2 bucket sippy enable my-bucket --provider s3 --bucket source --access-key-id <KEY> --secret-access-key <SECRET>

Copies on-demand as objects are requested.

Wrangler Commands

# Bucket
wrangler r2 bucket create|delete|list|info <name>

# Object
wrangler r2 object put|get|delete <bucket>/<key> [--file <path>]

# CORS
wrangler r2 bucket cors set|get|delete <bucket>

# Lifecycle
wrangler r2 bucket lifecycle list|add|remove <bucket>

# Notifications
wrangler r2 bucket notification list|create|delete <bucket>

# Sippy
wrangler r2 bucket sippy enable|disable|get <bucket>

Limits

| Parameter | Limit | | ------------------- | ------------ | | Buckets per account | 1,000,000 | | Object size | 5 TiB | | Single upload | 5 GiB | | Multipart parts | 10,000 | | Key length | 1,024 bytes | | Metadata size | 8,192 bytes | | Delete batch | 1,000 keys | | Lifecycle rules | 1,000/bucket | | Notification rules | 100/bucket |

Pricing

| Metric | Standard | Infrequent Access | | --------- | --------- | ----------------- | | Storage | $0.015/GB | $0.01/GB | | Class A | $4.50/M | $9.00/M | | Class B | $0.36/M | $0.90/M | | Retrieval | Free | $0.01/GB | | Egress | Free | Free |

Free tier: 10 GB storage, 1M Class A, 10M Class B.

Class A: PUT, COPY, LIST, CreateMultipartUpload Class B: GET, HEAD Free: DELETE, AbortMultipartUpload

See pricing.md for optimization tips.

Conditional Operations

const object = await env.MY_BUCKET.get("file.txt", {
  onlyIf: { etagMatches: expectedEtag },
  // or: etagDoesNotMatch, uploadedBefore, uploadedAfter
});

// Or from HTTP headers
const object = await env.MY_BUCKET.get("file.txt", { onlyIf: request.headers });

Server-Side Encryption (SSE-C)

await env.MY_BUCKET.put("secret.txt", data, { ssecKey: encryptionKey });
const object = await env.MY_BUCKET.get("secret.txt", { ssecKey: encryptionKey });

Lost key = lost data.

Prohibitions

• ❌ Do not use r2.dev for production
• ❌ Do not store encryption keys in code
• ❌ Do not skip CORS for browser access
• ❌ Do not ignore multipart limits (5 MiB min)
• ❌ Do not use presigned URLs with custom domains

References

• binding.md — Binding configuration
• api.md — Workers API reference
• presigned-urls.md — Browser integration
• multipart.md — Large file uploads
• lifecycle.md — Object expiration
• pricing.md — Cost optimization

Links

• Documentation
• Changelog

Cross-References

• cloudflare-workers — Worker development
• cloudflare-pages — Pages with R2
• cloudflare-queues — Event consumers
• cloudflare-d1 — SQL database