​
Database Setup

Create a Redis database using Upstash Console or Upstash CLI. Select the global to minimize the latency from all edge locations. Copy the UPSTASH_REDIS_REST_URL and UPSTASH_REDIS_REST_TOKEN for the next steps.

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Project Setup

We will use Fastly CLI for deployment, so please install Fastly CLI. Create a folder for your project and run fastly init. Select [2] JavaScript, then [2] Empty starter for JavaScript 
> fastly compute init

Creating a new Compute@Edge project.

Press ^C at any time to quit.

Name: [fastly-upstash]
Description:
Author: [enes@upstash.com]
Language:
[1] Rust
[2] JavaScript
[3] AssemblyScript (beta)
[4] Other ('bring your own' Wasm binary)
Choose option: [1] 2
Starter kit:
[1] Default starter for JavaScript
    A basic starter kit that demonstrates routing, simple synthetic responses and
    overriding caching rules.
    https://github.com/fastly/compute-starter-kit-javascript-default
[2] Empty starter for JavaScript
    An empty application template for the Fastly Compute@Edge environment which simply
    returns a 200 OK response.
    https://github.com/fastly/compute-starter-kit-javascript-empty
Choose option or paste git URL: [1] 2
Install @upstash/redis: 
npm install @upstash/redis
Now, we will create a Fastly Compute service by running, fastly compute publish. You need to add your Upstash database’s endpoint as a backend and select 443 as its port. 
> fastly compute publish
✓ Initializing...
✓ Verifying package manifest...
✓ Verifying local javascript toolchain...
✓ Building package using javascript toolchain...
✓ Creating package archive...

SUCCESS: Built package 'fastly-upstash' (pkg/fastly-upstash.tar.gz)


There is no Fastly service associated with this package. To connect to an existing service
add the Service ID to the fastly.toml file, otherwise follow the prompts to create a
service now.

Press ^C at any time to quit.

Create new service: [y/N] y

✓ Initializing...
✓ Creating service...

Domain: [supposedly-included-corgi.edgecompute.app]

Backend (hostname or IP address, or leave blank to stop adding backends): global-concise-scorpion-30984.upstash.io
Backend port number: [80] 443
Backend name: [backend_1] upstash

Backend (hostname or IP address, or leave blank to stop adding backends):

✓ Creating domain 'supposedly-smart-corgi.edgecompute.app'...
✓ Creating backend 'upstash' (host: global-concise-scorpion-30984.upstash.io, port: 443)...
✓ Uploading package...
✓ Activating version...

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The Code

Update src/index.js as below: 
import { Redis } from "@upstash/redis/fastly";

addEventListener("fetch", (event) => event.respondWith(handleRequest(event)));

async function handleRequest(event) {
  const redis = new Redis({
    url: "UPSTASH_REDIS_REST_URL",
    token: "UPSTASH_REDIS_REST_TOKEN",
    backend: "upstash",
  });
  const data = await redis.incr("count");
  return new Response("View Count:" + data, { status: 200 });
}

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Deploy

Deploy: fastly compute deploy After deployment, the CLI logs the endpoint. You can check the logs with: fastly log-tail --service-id=<YOUR_FASTLY_SERVICE_ID>

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Run Locally

To run the function locally add the backend to your fastly.toml as below: 
[local_server.backends.upstash]
url = "UPSTASH_REDIS_REST_URL"
Then run: fastly compute serve