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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. See 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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Step-1: Create Redis Database

Create a free Global database from Upstash Console. Find your REST URL and token in the database details page in the console. Copy them. Connect your database with redis-cli and add some greetings 
usw1-selected-termite-30690.upstash.io:30690> set GB "Ey up?"
OK
usw1-selected-termite-30690.upstash.io:30690> set US "Yo, what’s up?"
OK
usw1-selected-termite-30690.upstash.io:30690> set TR "Naber dostum?"
OK
usw1-selected-termite-30690.upstash.io:30690> set DE "Was ist los?"

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Step-2: Edge Function

The best way to work with Cloudflare Workers is to use Wrangler. After installing and configuring wrangler, create a folder for your project inside the folder run: wrangler init Choose yes to create package.json, no to typescript and yes to create a worker in src/index.js. It will create wrangler.toml, package.json and src/index.js. Append the Upstash REST URL and token to the toml as below: 
# wrangler.toml

# existing config

[vars]
UPSTASH_REDIS_REST_TOKEN = "AX_sASQgODM5ZjExZGEtMmI3Mi00Mjcwk3NDIxMmEwNmNkYjVmOGVmZTk5MzQ="
UPSTASH_REDIS_REST_URL = "https://us1-merry-macaque-31458.upstash.io/"
Install upstash-redis: npm install @upstash/redis Replace src/index.js with the following: 
// src/index.js

import { Redis } from "@upstash/redis/cloudflare";

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

    const country = request.headers.get("cf-ipcountry");
    if (country) {
      const greeting = await redis.get(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 correct greeting for that location using the Redis REST API.

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Run locally

Run wrangler dev and open your browser at localhost:8787.

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Build and Deploy

Build and deploy your app to Cloudflare by running: wrangler publish The url of your app will be logged: https://using-cloudflare-workers.upstash.workers.dev/

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Typescript example

We also have a typescript example, available here.
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