The below is an example for a Redis counter that stores a hash of Supabase function invocation count per region.

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Redis database setup

Create a Redis database using the Upstash Console or Upstash CLI.

Select the Global type to minimize the latency from all edge locations. Copy the UPSTASH_REDIS_REST_URL and UPSTASH_REDIS_REST_TOKEN to your .env file.

You’ll find them under Details > REST API > .env.

cp supabase/functions/upstash-redis-counter/.env.example supabase/functions/upstash-redis-counter/.env

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Code

Make sure you have the latest version of the Supabase CLI installed.

Create a new function in your project:

supabase functions new upstash-redis-counter

And add the code to the index.ts file:

index.ts
import { serve } from "https://deno.land/std@0.177.0/http/server.ts";
import { Redis } from "https://deno.land/x/upstash_redis@v1.19.3/mod.ts";
console.log(`Function "upstash-redis-counter" up and running!`);
serve(async (_req) => {
  try {
    const redis = new Redis({
      url: Deno.env.get("UPSTASH_REDIS_REST_URL")!,
      token: Deno.env.get("UPSTASH_REDIS_REST_TOKEN")!,
    });
    const deno_region = Deno.env.get("DENO_REGION");
    if (deno_region) {
      // Increment region counter
      await redis.hincrby("supa-edge-counter", deno_region, 1);
    } else {
      // Increment localhost counter
      await redis.hincrby("supa-edge-counter", "localhost", 1);
    }
    // Get all values
    const counterHash: Record<string, number> | null = await redis.hgetall(
      "supa-edge-counter"
    );
    const counters = Object.entries(counterHash!)
      .sort(([, a], [, b]) => b - a) // sort desc
      .reduce(
        (r, [k, v]) => ({
          total: r.total + v,
          regions: { ...r.regions, [k]: v },
        }),
        {
          total: 0,
          regions: {},
        }
      );
    return new Response(JSON.stringify({ counters }), { status: 200 });
  } catch (error) {
    return new Response(JSON.stringify({ error: error.message }), {
      status: 200,
    });
  }
});

​
Run locally

supabase start
supabase functions serve upstash-redis-counter --no-verify-jwt --env-file supabase/functions/upstash-redis-counter/.env

Navigate to http://localhost:54321/functions/v1/upstash-redis-counter.

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Deploy

supabase functions deploy upstash-redis-counter --no-verify-jwt
supabase secrets set --env-file supabase/functions/upstash-redis-counter/.env

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