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Edge Functions

Upstash Redis

A Redis counter example that stores a hash of function invocation count per region. Find the code on GitHub.

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

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:

import { Redis } from 'npm:@upstash/redis@^1'
import { withSupabase } from 'npm:@supabase/server@^1'
console.log(`Function "upstash-redis-counter" up and running!`)
// Open endpoint for testing. In production, implement an authorization layer in the handler or switch the auth mode.
export default {
  fetch: withSupabase({ auth: 'none' }, async (req, ctx) => {
    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 Response.json({ counters })
    } catch (error) {
      return Response.json({ error: error.message }, { status: 500 })
    }
  }),
}

Run locally#

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

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

Deploy#

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