Supabase

Supabase is an open-source Firebase alternative with PostgreSQL, auth, storage, and real-time built in.

Table of Contents

• Overview
• Quick Start
  • 1. Create Account
  • 2. Create Project
  • 3. Get Credentials
  • 4. Configure Juntos
  • 5. Deploy
• Environment Variables
• Architecture
• Migrations
  • Migration Files
• Real-Time Features
  • How It Works
  • Configuration
• Row Level Security (RLS)
  • With Juntos
• Authentication
• Storage
• Edge Functions
• Local Development
  • Local Environment
• Troubleshooting
  • PostgREST errors
  • Migration failures
  • Real-time not working
• Pricing
• Resources

Overview

Quick Start

1. Create Account

Sign up at supabase.com (GitHub login available).

2. Create Project

1. Click New Project
2. Choose organization
3. Name your project and set a database password
4. Choose a region close to your users
5. Wait for provisioning (~2 minutes)

3. Get Credentials

Go to Project Settings → API:

• Project URL — https://xxx.supabase.co
• anon public key — For client-side access

Go to Project Settings → Database:

• Connection string — For migrations (use URI format)

4. Configure Juntos

Add to .env.local:

SUPABASE_URL=https://xxx.supabase.co
SUPABASE_ANON_KEY=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
DATABASE_URL=postgres://postgres:password@db.xxx.supabase.co:5432/postgres

5. Deploy

bin/juntos db:prepare -d supabase
bin/juntos deploy -d supabase

Environment Variables

Architecture

Supabase uses two connection methods:

1. PostgREST (HTTP) — For application queries via REST API
2. Direct PostgreSQL — For migrations and admin tasks

Juntos automatically uses:

• PostgREST for normal CRUD operations (works in serverless)
• Direct PostgreSQL for migrations (requires DATABASE_URL)

Migrations

Since PostgREST doesn’t support DDL (schema changes), migrations use a direct PostgreSQL connection:

# Runs via direct Postgres connection
bin/juntos db:migrate -d supabase

This requires DATABASE_URL to be set. In CI/CD, ensure this variable is available during build.

Migration Files

Create migrations in db/migrate/:

# db/migrate/001_create_messages.rb
class CreateMessages < ActiveRecord::Migration
  def up
    create_table :messages do |t|
      t.string :content, null: false
      t.string :room, null: false
      t.timestamps
    end
  end

  def down
    drop_table :messages
  end
end

Real-Time Features

Supabase includes real-time subscriptions. Juntos automatically uses Supabase Realtime for Turbo Streams when deployed with Supabase:

<%# In your view %>
<%= turbo_stream_from "chat_room" %>

How It Works

1. Server broadcasts to chat_room channel via Supabase Realtime
2. Client subscribes and receives updates
3. Turbo renders the stream automatically

Configuration

Real-time is enabled by default. Juntos detects Supabase and configures the broadcast adapter automatically.

Row Level Security (RLS)

Supabase encourages Row Level Security for authorization. Enable RLS on tables:

-- In a migration or Supabase SQL editor
ALTER TABLE messages ENABLE ROW LEVEL SECURITY;

-- Allow anyone to read messages
CREATE POLICY "Messages are viewable by everyone"
  ON messages FOR SELECT
  USING (true);

-- Only authenticated users can insert
CREATE POLICY "Users can insert messages"
  ON messages FOR INSERT
  WITH CHECK (auth.role() = 'authenticated');

With Juntos

Since Juntos apps typically handle auth at the application layer, you might use broader policies:

-- Allow all operations (auth handled in app)
CREATE POLICY "Allow all" ON messages
  USING (true)
  WITH CHECK (true);

Authentication

Supabase includes authentication, but Juntos apps typically implement their own auth. You can:

1. Use Supabase Auth — Integrate with @supabase/supabase-js
2. Use application auth — Handle in your Rails models/controllers

Storage

Supabase includes object storage. Access via the Supabase client:

import { createClient } from '@supabase/supabase-js';

const supabase = createClient(
  process.env.SUPABASE_URL,
  process.env.SUPABASE_ANON_KEY
);

// Upload file
const { data, error } = await supabase.storage
  .from('avatars')
  .upload('public/avatar.png', file);

Edge Functions

Supabase offers Deno-based edge functions. These are separate from Juntos—use them for:

• Webhooks
• Background jobs
• Third-party integrations

Local Development

Supabase provides a local development stack:

# Install Supabase CLI
npm install -g supabase

# Start local stack
supabase start

This runs PostgreSQL, PostgREST, and other services locally.

Local Environment

# .env.local for local development
SUPABASE_URL=http://localhost:54321
SUPABASE_ANON_KEY=your-local-anon-key
DATABASE_URL=postgres://postgres:postgres@localhost:54322/postgres

Troubleshooting

PostgREST errors

PostgREST returns structured errors. Common issues:

Migration failures

Ensure DATABASE_URL uses the direct connection (port 5432), not the pooled connection (port 6543).

Real-time not working

1. Verify Realtime is enabled in Supabase dashboard
2. Check that the table has REPLICA IDENTITY set:

   ALTER TABLE messages REPLICA IDENTITY FULL;
   

Pricing

The free tier includes 2 projects, sufficient for development and small apps.

Resources

• Supabase Documentation
• PostgREST Documentation
• Supabase Realtime
• Row Level Security