Technical reference

Cloudflare Cheatsheet

Edge compute, delivery, storage, and security platform

Must Know

bash

Create a Worker

npm create cloudflare@latest -- my-worker
cd my-worker
npm run dev
npm run deploy

javascript

Worker Handler

Workers use the web-standard Request, Response, and fetch APIs.

export default {
  async fetch(request, env, ctx) {
    return Response.json({ ok: true });
  },
};

Storage

Choose the Right Store

Each storage product has different consistency and access characteristics.

R2  -> object and file storage
D1  -> relational SQL at the edge
KV  -> read-heavy key/value configuration
Durable Objects -> coordinated state
Queues -> asynchronous delivery

javascript

R2 Binding

export default {
  async fetch(request, env) {
    const object = await env.MY_BUCKET.get("reports/latest.pdf");
    if (!object) return new Response("Not found", { status: 404 });
    return new Response(object.body, { headers: object.httpMetadata });
  },
};

javascript

D1 Query

Bind input values instead of constructing SQL strings.

const result = await env.DB
  .prepare("select id, name from users where id = ?")
  .bind(userId)
  .first();

Caching & Delivery

javascript

Cache Response

Define who may cache a response and how it will be invalidated.

const response = await fetch(request);
const cached = new Response(response.body, response);
cached.headers.set("Cache-Control", "public, max-age=60, s-maxage=3600");
return cached;

Cache Safety

Caching can leak data when identity and authorization are ignored.

do not cache private user responses
include representation-changing values in the cache key
set explicit TTLs
plan purge/invalidation
measure hit ratio and stale content

Production Notes

json

Bindings and Secrets

Use bindings for platform resources and secret storage for credentials.

npx wrangler secret put API_TOKEN

# wrangler.jsonc
{
  "r2_buckets": [{ "binding": "MY_BUCKET", "bucket_name": "files" }],
  "d1_databases": [{ "binding": "DB", "database_name": "app" }]
}

Edge Checklist

Running near users does not remove normal distributed-system failure modes.

set upstream timeouts
bound request and response sizes
validate every input
use structured logs
understand regional cache behavior
handle retries and duplicates
monitor CPU and subrequest limits