GitHub Repository

You can find the project source code on GitHub.
 This tutorial showcases using Redis with REST API in Cloudflare Workers. We will write a sample edge function (Cloudflare Workers) which will show a custom greeting depending on the location of the client. We will load the greeting message from Redis so you can update it without touching the code.

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Why Upstash?

  • Cloudflare Workers does not allow TCP connections. Upstash provides REST API on top of the Redis database.
  • Upstash is a serverless offering with per-request pricing which fits for edge and serverless functions.
  • Upstash Global database provides low latency all over the world.

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Prerequisites

  1. Install the Cloudflare Wrangler CLI with npm install wrangler --save-dev

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Project Setup

Create a Cloudflare Worker with the following options: 
➜  tutorials > ✗ npx wrangler init
╭ Create an application with Cloudflare Step 1 of 3
│
├ In which directory do you want to create your application?
│ dir ./greetings-cloudflare
│
├ What would you like to start with?
│ category Hello World example
│
├ Which template would you like to use?
│ type Hello World Worker
│
├ Which language do you want to use?
│ lang TypeScript
│
├ Copying template files
│ files copied to project directory
│
├ Updating name in `package.json`
│ updated `package.json`
│
├ Installing dependencies
│ installed via `npm install`
│
╰ Application created

╭ Configuring your application for Cloudflare Step 2 of 3
│
├ Installing @cloudflare/workers-types
│ installed via npm
│
├ Adding latest types to `tsconfig.json`
│ added @cloudflare/workers-types/2023-07-01
│
├ Retrieving current workerd compatibility date
│ compatibility date 2024-10-22
│
├ Do you want to use git for version control?
│ no git
│
╰ Application configured
Install Upstash Redis: 
cd greetings-cloudflare
npm install @upstash/redis

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Database Setup

Create a Redis database using Upstash Console or Upstash CLI and copy the UPSTASH_REDIS_REST_URL and UPSTASH_REDIS_REST_TOKEN into your wrangler.toml file.
wrangler.toml
# existing config

[vars]
UPSTASH_REDIS_REST_URL = <YOUR_URL>
UPSTASH_REDIS_REST_TOKEN = <YOUR_TOKEN>
Using CLI Tab in the Upstash Console, add some greetings to your database: CLI Tab

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Greetings Function Setup

Update src/index.ts:
src/index.ts
import { Redis } from '@upstash/redis/cloudflare';

type RedisEnv = {
	UPSTASH_REDIS_REST_URL: string;
	UPSTASH_REDIS_REST_TOKEN: string;
};

export default {
	async fetch(request: Request, env: RedisEnv) {
		const redis = Redis.fromEnv(env);

		const country = request.headers.get('cf-ipcountry');
		if (country) {
			const greeting = await redis.get<string>(country);
			if (greeting) {
				return new Response(greeting);
			}
		}

		return new Response('Hello!');
	},
};
The code tries to find out the user’s location checking the “cf-ipcountry” header. Then it loads the corresponding greeting for that location using the Redis REST API.

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Run Locally

Run the following command to start your dev session: 
npx wrangler dev
Visit localhost:8787

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Build and Deploy

Build and deploy your app to Cloudflare: 
npx wrangler deploy
Visit the output url.