06.06 — `lib/redis.ts` + Upstash#

Source file: lib/redis.ts

Code#

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

const redis = new Redis({
  url: process.env.UPSTASH_REDIS_REST_URL,
  token: process.env.UPSTASH_REDIS_REST_TOKEN,
});

export default redis;

Why `@upstash/redis` rather than `ioredis`#

Criterion	`ioredis`	`@upstash/redis`
Protocol	TCP / RESP	HTTP / REST
Edge runtime	❌ No	✅ Yes
Connection	Persistent	Per-request
Latency (warm)	< 1ms	50–100ms
Latency (cold)	200ms+	50–100ms
Cost	Variable	Pay-per-request
Setup	Self-hosted Redis	Upstash dashboard (managed)

Edge doesn’t accept persistent TCP connections — each worker is ephemeral. Upstash REST it is.

Singleton#

const redis = new Redis({...});
export default redis;

Created once at module import (cold start), reused for every request the worker serves. With reasonable traffic the worker stays warm.

Env var consumption#

url: process.env.UPSTASH_REDIS_REST_URL,
token: process.env.UPSTASH_REDIS_REST_TOKEN,

UPSTASH_REDIS_REST_URL    = "https://us1-something-12345.upstash.io"
UPSTASH_REDIS_REST_TOKEN  = "AcdefGHi..."

The token is JWT-like, generated by Upstash and scoped to a specific Redis database.

`vercel env add`#

The README details:

vercel env add API_SECRET
vercel env add UPSTASH_REDIS_REST_URL
vercel env add UPSTASH_REDIS_REST_TOKEN
vercel deploy

Three vercel env adds, then vercel deploy. No local config needed.

API#

Redis method	Endpoint	Use
`redis.set(key, value, { ex: ttl })`	`/api/otp`	`SET` with TTL
`redis.scan(cursor, { match, count })`	`/api/otp-history`	Cursor-based `SCAN`
`redis.mget(...keys)`	`/api/otp-history`	`MGET` (multi-get)

Error handling#

@upstash/redis throws on network or server errors. The code doesn’t catch them — they bubble up to Vercel’s handler as 500 Internal Server Error.

On Igoristan: the user sees an OTP error and retries.
On Ocarina: transient_errors catches and retries.

No explicit timeout#

const redis = new Redis({
  url: ...,
  token: ...,
});

No explicit timeout. @upstash/redis defaults to ~5s. The Edge runtime has its own hard limit (10s on Vercel) — so even if the client doesn’t time out, Vercel will.

06.06 — lib/redis.ts + Upstash#