Problem: Cannot dynamically set database connection for Supabase Preview Branches

[Nciso]

Problem

When using Supabase Preview Branches, each preview branch has its own database URL. Currently, EDGE_WORKER_DB_URL must be set as a static environment variable, which prevents connecting to the correct preview branch database dynamically.

This is only a problem for preview branches - production/main branch works fine! ✨

What I Want to Do

I want to derive the pooler connection string from SUPABASE_DB_URL (which is already available and branch-aware):

const directUrl = Deno.env.get('SUPABASE_DB_URL');
const poolerUrl = directUrl.replace(':5432/', ':6543/');

EdgeWorker.startFlowWorker(MyFlow, {
  connectionString: poolerUrl, // ❌ Currently doesn't work
});

Why It Doesn't Work

SupabasePlatformAdapter requires EDGE_WORKER_DB_URL as a mandatory environment variable during initialization:

// pkgs/edge-worker/src/platform/SupabasePlatformAdapter.ts
const required = [
  'EDGE_WORKER_DB_URL',  // ❌ Always required
  // ...
];

Even if I provide connectionString in the worker config:

1. The adapter still requires the env var
2. context.sql in handlers uses the env var connection, not the config one

The Solution I'm Hoping For

Make EDGE_WORKER_DB_URL optional when connectionString is provided in config, or auto-derive it from SUPABASE_DB_URL.

Priority:

1. connectionString in worker config (explicit override)
2. EDGE_WORKER_DB_URL env var (backwards compatibility)
3. Auto-derive from SUPABASE_DB_URL → convert :5432/ to :6543/

This way preview branches can automatically connect to their branch-specific database!

Why This Matters

• Can't pre-configure env vars for every preview branch
• SUPABASE_DB_URL is already available and branch-aware
• Just need to convert it to pooler format (:5432/ → :6543/)

Current workaround: Manually set EDGE_WORKER_DB_URL per branch, which doesn't scale.

Related Files

• pkgs/edge-worker/src/platform/SupabasePlatformAdapter.ts - Validation logic
• pkgs/edge-worker/src/EdgeWorker.ts - Worker startup
• pkgs/edge-worker/src/core/workerConfigTypes.ts - Already documents connectionString option

Current workaround: I'm manually setting the env variable after preview creation, but it would be great if this could work automatically. I'd be happy to help with the implementation if needed!

Thanks! 🙏