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Cloudflare R2 S3-compatible object storage. Use for buckets, uploads, CORS, presigned URLs, or encountering R2_ERROR, CORS failures, multipart issues.
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Cloudflare R2 S3-compatible object storage. Use for buckets, uploads, CORS, presigned URLs, or encountering R2_ERROR, CORS failures, multipart issues. 📦 Ships with claude-skills
</> SKILL.md
cloudflare-r2.SKILL.md
---
name : cloudflare-r2
description : "Cloudflare R2 S3-compatible object storage. Use for buckets, uploads, CORS, presigned URLs, or encountering R2_ERROR, CORS failures, multipart issues."
license : MIT
metadata:
version: "3.0.0"
last_verified: "2025-12-27"
production_tested: true
token_savings: "~65%"
errors_prevented: 12
templates_included: 5
references_included: 11
agents_included: 5
commands_included: 4
scripts_included: 3
wrangler_version: "4.50.0"
workers_types_version: "4.20251126.0"
aws4fetch_version: "1.0.20"
keywords:
- r2
- r2 storage
- cloudflare r2
- r2 bucket
- r2 upload
- r2 download
- r2 binding
- object storage
- s3 compatible
- r2 cors
- presigned urls
- multipart upload
- r2 api
- r2 workers
- file upload
- asset storage
- R2_ERROR
- R2Bucket
Flowy AI Flows that just work. Hand-picked Claude Code plugins that fire the right skill as you prompt.
- r2 metadata
- custom metadata
- http metadata
- content-type
- cache-control
- aws4fetch
- s3 client
- bulk delete
- r2 list
- storage class
---
# Cloudflare R2 Object Storage
**Status**: Production Ready ✅ | **Last Verified**: 2025-12-27 | **v3.0.0**
**Contents**: [Quick Start](#quick-start-5-minutes) • [New Features](#new-r2-features-2025) • [Core R2 API](#core-r2-workers-api-quick-reference) • [Critical Rules](#critical-rules) • [Agents & Commands](#available-agents--commands) • [References](#when-to-load-references)
---
## Quick Start (5 Minutes)
### 1. Create R2 Bucket
```bash
bunx wrangler r2 bucket create my-bucket
```
**Bucket naming:** 3-63 chars, lowercase, numbers, hyphens only
### 2. Configure Binding
Add to `wrangler.jsonc`:
```jsonc
{
"name": "my-worker",
"main": "src/index.ts",
"compatibility_date": "2025-10-11",
"r2_buckets": [
{
"binding": "MY_BUCKET", // env.MY_BUCKET
"bucket_name": "my-bucket", // Actual bucket
"preview_bucket_name": "my-bucket-preview" // Optional: dev bucket
}
]
}
```
**CRITICAL:** `binding` = code access name, `bucket_name` = actual R2 bucket
### 3. Basic Upload/Download
```typescript
import { Hono } from 'hono';
type Bindings = {
MY_BUCKET: R2Bucket;
};
const app = new Hono<{ Bindings: Bindings }>();
// Upload
app.put('/upload/:filename', async (c) => {
const filename = c.req.param('filename');
const body = await c.req.arrayBuffer();
const object = await c.env.MY_BUCKET.put(filename, body, {
httpMetadata: {
contentType: c.req.header('content-type') || 'application/octet-stream',
},
});
return c.json({
success: true,
key: object.key,
size: object.size,
});
});
// Download
app.get('/download/:filename', async (c) => {
const object = await c.env.MY_BUCKET.get(c.req.param('filename'));
if (!object) {
return c.json({ error: 'Not found' }, 404);
}
return new Response(object.body, {
headers: {
'Content-Type': object.httpMetadata?.contentType || 'application/octet-stream',
'ETag': object.httpEtag,
},
});
});
export default app;
```
**Load `references/setup-guide.md` for complete setup walkthrough.**
---
## New R2 Features (2025)
**🆕 R2 SQL Integration** - Query CSV/Parquet/JSON data with distributed SQL. Analytics without ETL. **Load `references/r2-sql-integration.md`**
**🆕 Data Catalog (Apache Iceberg)** - Table versioning, time-travel queries, schema evolution. Spark/Snowflake integration. **Load `references/data-catalog-iceberg.md`**
**🆕 Event Notifications** - Trigger Workers on object changes (upload/delete). Automate image processing, backups, webhooks. **Load `references/event-notifications.md`**
**Advanced Features** - Storage classes, bucket locks (compliance), tus resumable uploads, SSE-C encryption. **Load `references/advanced-features.md`**
**Zero Trust Security** - Cloudflare Access integration with SSO, MFA, identity policies, audit logging. **Load `references/cloudflare-access-integration.md`**
**Performance Tuning** - Caching strategies, compression, range requests, ETags, monitoring best practices. **Load `references/performance-optimization.md`**
---
## Core R2 Workers API - Quick Reference
### put() - Upload Objects
```typescript
await env.MY_BUCKET.put(key, data, options?)
```
Upload with metadata, prevent overwrites with `onlyIf`. **Load `references/workers-api.md`** for complete R2PutOptions.
### get() - Download Objects
```typescript
const object = await env.MY_BUCKET.get(key, options?)
```
Returns `R2ObjectBody | null`. Supports range requests, conditional operations. **Load `references/workers-api.md`** for read methods (text(), json(), arrayBuffer(), blob()).
### head() - Get Metadata Only
```typescript
const object = await env.MY_BUCKET.head(key)
```
Check existence, get size, etag, metadata without downloading body. Useful for validation and caching.
### delete() - Delete Objects
```typescript
await env.MY_BUCKET.delete(key | keys[]) // Single or bulk (max 1000)
```
Bulk delete up to 1000 keys in single call. Always succeeds (idempotent).
### list() - List Objects
```typescript
const listed = await env.MY_BUCKET.list(options?)
```
Pagination with cursor, prefix filtering, delimiter for folders. **Load `references/workers-api.md`** for R2ListOptions.
### createMultipartUpload() - Large Files (>100MB)
```typescript
const multipart = await env.MY_BUCKET.createMultipartUpload(key, options?)
```
For files >100MB. **Load `references/common-patterns.md`** for complete multipart workflow with part upload and completion.
**Load `references/workers-api.md` when**: Need complete API reference, interface definitions (R2Object, R2ObjectBody, R2PutOptions, R2GetOptions), conditional operations, checksums, or advanced options.
---
## Critical Rules
### Always Do ✅
1. **Set contentType on uploads** - Files will download as binary otherwise
2. **Use batch delete** for multiple objects (up to 1000 keys)
3. **Set cache headers** for static assets (`cacheControl`)
4. **Use presigned URLs** for large client uploads
5. **Use multipart upload** for files >100MB
6. **Set CORS policy** before browser uploads
7. **Set expiry times** on presigned URLs (1-24 hours)
8. **Handle errors** with try/catch
9. **Use head()** when you only need metadata (not get())
10. **Use conditional operations** to prevent overwrites
### Never Do ❌
1. **Never expose R2 access keys** in client-side code
2. **Never skip contentType** (files will download as binary)
3. **Never delete in loops** (use batch delete)
4. **Never upload without error handling**
5. **Never skip CORS** for browser uploads
6. **Never use multipart for small files** (<5MB overhead)
7. **Never delete >1000 keys** in single call (will fail)
8. **Never assume uploads succeed** (always check response)
9. **Never skip presigned URL expiry** (security risk)
10. **Never hardcode bucket names** (use bindings)
---
## Top Use Cases
### Use Case 1: Image/Asset Storage
```typescript
app.put('/api/upload/image', async (c) => {
const file = await c.req.parseBody();
const image = file['image'] as File;
await c.env.MY_BUCKET.put(`images/${image.name}`, image.stream(), {
httpMetadata: {
contentType: image.type,
cacheControl: 'public, max-age=31536000, immutable',
},
});
return c.json({ success: true });
});
```
### Use Case 2: Direct Client Upload (Presigned URLs)
Generate secure upload URLs for client-side uploads. See `templates/r2-presigned-urls.ts` for complete implementation using aws4fetch.
### Additional Patterns in References
**Load `references/common-patterns.md` for**:
- Multipart upload (files >100MB) - Complete workflow with part management
- Bulk operations - Batch delete, cleanup patterns with pagination
- Custom metadata tracking - User files, versions, approval workflows
- Versioned file storage - Version history with latest pointer pattern
- Backup & archive patterns - Automated backups with retention policies
- Thumbnail generation & caching - On-demand image processing
- Static site hosting - SPA fallback and cache strategies
- CDN with origin fallback - R2 as cache layer
**Load `templates/r2-multipart-upload.ts`** for complete multipart example.
---
## Available Agents & Commands
### Autonomous Agents
Agents handle complex multi-step workflows automatically:
- **r2-setup-automator** - Complete R2 setup (bucket creation → binding → TypeScript types → deployment)
- **multipart-orchestrator** - Large file uploads with chunking, error recovery, and progress tracking
- **cors-debugger** - Systematic CORS troubleshooting with configuration generation and testing
- **s3-migration-planner** - AWS S3 to R2 migration planning, data transfer, and cost analysis
- **event-notification-setup** - Event-driven workflows with Workers, Queues, and automation
### Quick Commands
Fast access to common R2 operations:
- **/r2-setup** - Create bucket and configure binding in wrangler.jsonc
- **/r2-presigned-url** - Generate presigned URLs for secure client-side uploads/downloads
- **/r2-cors-debug** - Diagnose and fix CORS configuration issues
- **/r2-multipart-init** - Initialize multipart upload workflow for large files
---
## When to Load References
### Core References (Existing Features)
**`references/setup-guide.md`** - First-time setup, binding configuration, TypeScript types, deployment walkthrough
**`references/workers-api.md`** - Complete API reference (all methods + options), conditional operations, checksums
**`references/common-patterns.md`** - Multipart uploads, retry logic with backoff, batch operations, cache strategies
**`references/s3-compatibility.md`** - S3 migration guide, S3 client library usage, aws4fetch presigned URL signing
**`references/cors-configuration.md`** - Browser access setup, CORS debugging, security policies, Dashboard configuration
### New Features References (2025)
**`references/event-notifications.md`** - Event-driven automation, Queue integration, image processing, webhook triggers
**`references/advanced-features.md`** - Storage classes (cost optimization), bucket locks (compliance), tus resumable uploads, SSE-C encryption
**`references/r2-sql-integration.md`** - SQL queries on R2 data (CSV/Parquet/JSON), analytics patterns, performance tuning
**`references/data-catalog-iceberg.md`** - Apache Iceberg tables, time-travel queries, schema evolution, Spark/Snowflake integration
**`references/cloudflare-access-integration.md`** - Zero Trust security, SSO (Google/Okta/Azure AD), identity policies, MFA, audit logging
**`references/performance-optimization.md`** - Caching (browser/CDN/Workers), compression (gzip/Brotli), range requests, ETags, monitoring
---
## Using Bundled Resources
### References (references/)
- **setup-guide.md** - Complete setup walkthrough (bucket creation → deployment)
- **workers-api.md** - Complete Workers API reference (all methods + options)
- **common-patterns.md** - Advanced patterns (multipart, retry, batch, performance)
- **s3-compatibility.md** - S3 compatibility guide (migration, aws4fetch, S3 clients)
- **cors-configuration.md** - CORS setup guide (Dashboard, scenarios, troubleshooting, security)
### Templates (templates/)
- **r2-simple-upload.ts** - Basic upload/download Worker
- **r2-multipart-upload.ts** - Complete multipart upload implementation
- **r2-presigned-urls.ts** - Presigned URL generation (upload + download)
- **r2-cors-config.json** - CORS configuration examples
- **wrangler-r2-config.jsonc** - Complete wrangler.jsonc with R2 binding
---
## CORS Configuration
Configure CORS for browser uploads/downloads. **Load `references/cors-configuration.md`** for complete guide including Dashboard setup, common scenarios, troubleshooting, and security best practices.
---
## Error Handling
```typescript
try {
await env.MY_BUCKET.put(key, data);
} catch (error: any) {
const message = error.message;
if (message.includes('R2_ERROR')) {
// Generic R2 error
} else if (message.includes('exceeded')) {
// Quota exceeded
} else if (message.includes('precondition')) {
// Conditional operation failed (onlyIf)
}
console.error('R2 Error:', message);
return c.json({ error: 'Storage operation failed' }, 500);
}
```
**Load `references/common-patterns.md`** for retry logic with exponential backoff, circuit breaker patterns, and advanced error recovery.
---
## Known Issues Prevented
| Issue | Description | Solution |
|-------|-------------|----------|
| **CORS errors** | Browser can't upload/download | Configure CORS in bucket settings |
| **Files download as binary** | Missing content-type | Always set `httpMetadata.contentType` |
| **Presigned URL security** | URLs never expire | Always set `X-Amz-Expires` (1-24 hours) |
| **Multipart limits** | Parts >100MB or >10,000 parts | Keep parts 5MB-100MB, max 10,000 |
| **Bulk delete limits** | >1000 keys fails | Chunk deletes into batches of 1000 |
| **Metadata overflow** | >2KB custom metadata | Keep total under 2KB |
---
## Wrangler Commands
```bash
# Bucket management
wrangler r2 bucket create <BUCKET_NAME>
wrangler r2 bucket list
wrangler r2 bucket delete <BUCKET_NAME>
# Object management
wrangler r2 object put <BUCKET>/<KEY> --file=<PATH>
wrangler r2 object get <BUCKET>/<KEY> --file=<OUTPUT>
wrangler r2 object delete <BUCKET>/<KEY>
# List objects
wrangler r2 object list <BUCKET>
wrangler r2 object list <BUCKET> --prefix="folder/"
```
---
## Official Documentation
- **R2 Overview**: https://developers.cloudflare.com/r2/
- **Workers API**: https://developers.cloudflare.com/r2/api/workers/workers-api-reference/
- **Multipart Upload**: https://developers.cloudflare.com/r2/api/workers/workers-multipart-usage/
- **Presigned URLs**: https://developers.cloudflare.com/r2/api/s3/presigned-urls/
- **CORS Configuration**: https://developers.cloudflare.com/r2/buckets/cors/
---
**Questions? Issues?**
1. Check `references/setup-guide.md` for setup walkthrough
2. Review `references/workers-api.md` for API reference
3. See `references/common-patterns.md` for advanced patterns
4. Load `templates/` for working code examples
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