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.

1
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:

1
supabase functions new upstash-redis-counter

And add the code to the index.ts file:

1
import { Redis } from 'https://deno.land/x/upstash_redis@v1.19.3/mod.ts'
2
import { withSupabase } from 'npm:@supabase/server@^1'
3
4
console.log(`Function "upstash-redis-counter" up and running!`)
5
6
// Open endpoint for testing. In production, implement an authorization layer in the handler or switch the auth mode.
7
export default {
8
  fetch: withSupabase({ auth: 'none' }, async (req, ctx) => {
9
    try {
10
      const redis = new Redis({
11
        url: Deno.env.get('UPSTASH_REDIS_REST_URL')!,
12
        token: Deno.env.get('UPSTASH_REDIS_REST_TOKEN')!,
13
      })
14
15
      const deno_region = Deno.env.get('DENO_REGION')
16
      if (deno_region) {
17
        // Increment region counter
18
        await redis.hincrby('supa-edge-counter', deno_region, 1)
19
      } else {
20
        // Increment localhost counter
21
        await redis.hincrby('supa-edge-counter', 'localhost', 1)
22
      }
23
24
      // Get all values
25
      const counterHash: Record<string, number> | null = await redis.hgetall('supa-edge-counter')
26
      const counters = Object.entries(counterHash!)
27
        .sort(([, a], [, b]) => b - a) // sort desc
28
        .reduce((r, [k, v]) => ({ total: r.total + v, regions: { ...r.regions, [k]: v } }), {
29
          total: 0,
30
          regions: {},
31
        })
32
33
      return Response.json({ counters })
34
    } catch (error) {
35
      return Response.json({ error: error.message }, { status: 500 })
36
    }
37
  }),
38
}

Run locally#

1
supabase start
2
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#

1
supabase functions deploy upstash-redis-counter --no-verify-jwt
2
supabase secrets set --env-file supabase/functions/upstash-redis-counter/.env