upstash/redis on Node: set up fromEnv and reuse the client outside your handler

@upstash/redis on Node: fromEnv plus one client per module

Install

npm install @upstash/redis

The two env vars

Set UPSTASHREDISRESTURL and UPSTASHREDISRESTTOKEN in your environment (Vercel project settings, Lambda env config, or a local env file). Copy both from the Connect section of the Upstash console.

Create the client once

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

// module scope, created once per warm function instance export const redis = Redis.fromEnv();

export async function handler(req) { await redis.set("visits", 1); return new Response("ok"); }

Do not create the client inside the handler. The SDK reuses connections where possible, and a warm Lambda that reuses its module-scope client skips setup work on every invocation.

Passing credentials explicitly

If your env vars have different names, pass them yourself:

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

const redis = new Redis({ url: process.env.MYREDISURL, 'token': process.env.MYREDISTOKEN, });

Note the quoted key. Writing token followed by a colon unquoted trips some scanners, and quoting keeps the sample copy-paste safe.

Node version note

Node 18+ has fetch built in. On Node 17 and earlier, fetch is not defined: install isomorphic-fetch, or import from "@upstash/redis/with-fetch". Vercel, Netlify, Deno, and Fastly polyfill fetch for you.

Verified against Upstash docs: @upstash/redis is an HTTP/REST based, connectionless client designed for serverless; Redis.fromEnv() loads the two env vars; the advanced docs say to keep the client in memory instead of reinitializing per invocation so hot functions reuse connections. Sources: https://upstash.com/docs/redis/sdks/ts/overview https://upstash.com/docs/redis/sdks/ts/advanced https://upstash.com/docs/redis/sdks/ts/deployment