This quickstart will show you how to get started with Edge Flags in a Next.js project.

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1. Create a redis database

Go to console.upstash.com/redis and create a new global database. After creating the db, copy the UPSTASH_REDIS_REST_URL and UPSTASH_REDIS_REST_TOKEN to your .env file.

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2. Create a flag

Go to console.upstash.com/edge-flags and select the database you created in the previous step. Create a new flag and enable it. Then you can add some rules. Created In this case, the flag has a percentage and 2 rules. For 80% of the users the flag will be evaluated. For the other 20% the flag will immediately return false without evaluating the rules.
  • The first rule is a geo targeting rule. It will enable the flag for users in Germany or the United Kingdom.
  • The second rule is a custom attribute rule. It will enable the flag for users with the attribute userId set to chronark.
Rules are evaluated from top to bottom. If a rule matches, the flag will return the configured value and stop evaluating the remaining rules. If neither rule matches, the flag will return false Make sure you have enabled the flag by clicking on the toggle button in the top right corner. Now lets use the flag in our Next.js project.

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3. Install dependencies

npm install @upstash/edge-flags

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4. Create an edge function in your project

// /api/edge-flags.ts
import { createEdgeHandler } from "@upstash/edge-flags";

export default createEdgeHandler({
  cacheMaxAge: 0, // cache time in seconds, 0 disables the cache
  redisUrl: process.env.UPSTASH_REDIS_REST_URL!, // omit to load from env automatically
  redisToken: process.env.UPSTASH_REDIS_REST_TOKEN!, // omit to load from env automatically
});

/**
 * Edge flags only works in edge functions, it will break if you do not set the runtime
 */
export const config = {
  runtime: "edge",
};

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5. Query the flag in your frontend

// /app/index.tsx
import { useFlag } from "@upstash/edge-flags";
export default function Example() {
  const { isEnabled, isLoading, error } = useFlag("flag-name");

  if (error) return <div>Error: {error}</div>;
  if (isLoading) return <div>Loading...</div>;

  return <div>Is my feature enabled: {isEnabled}</div>;
}
For more information about client side usage, see here.