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.

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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:

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supabase functions new upstash-redis-counter

And add the code to the index.ts file:

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

Run locally

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supabase start
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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

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