Supabase

Supabase Core Skill

Core concepts, CLI workflow, and patterns common to all Supabase projects.

Sources: Supabase Docs | Supabase CLI

Core Principle

Local-first, migrations in version control, never touch production directly.

Develop locally with the Supabase CLI, capture all changes as migrations, and deploy through CI/CD.

Supabase Stack

CLI Setup

Install & Login

# macOS
brew install supabase/tap/supabase

# npm (alternative)
npm install -g supabase

# Login
supabase login

Initialize Project

# In your project directory
supabase init

# Creates:
# supabase/
# ├── config.toml      # Local config
# ├── seed.sql         # Seed data
# └── migrations/      # SQL migrations

Link to Remote

# Get project ref from dashboard URL: https://supabase.com/dashboard/project/<ref>
supabase link --project-ref <project-id>

# Pull existing schema
supabase db pull

Start Local Stack

supabase start

# Output:
# API URL: http://localhost:54321
# GraphQL URL: http://localhost:54321/graphql/v1
# DB URL: postgresql://postgres:postgres@localhost:54322/postgres
# Studio URL: http://localhost:54323
# Anon key: eyJ...
# Service role key: eyJ...

Migration Workflow

Option 1: Dashboard + Diff (Quick Prototyping)

# 1. Make changes in local Studio (localhost:54323)
# 2. Generate migration from diff
supabase db diff -f <migration_name>

# 3. Review generated SQL
cat supabase/migrations/*_<migration_name>.sql

# 4. Reset to test
supabase db reset

Option 2: Write Migrations Directly (Recommended)

# 1. Create empty migration
supabase migration new create_users_table

# 2. Edit the migration file
# supabase/migrations/<timestamp>_create_users_table.sql

# 3. Apply locally
supabase db reset

Option 3: ORM Migrations (Best DX)

Use Drizzle (TypeScript) or SQLAlchemy (Python) - see framework-specific skills.

Deploy Migrations

# Push to remote (staging/production)
supabase db push

# Check migration status
supabase migration list

Database Patterns

Enable RLS on All Tables

-- Always enable RLS
ALTER TABLE public.profiles ENABLE ROW LEVEL SECURITY;

-- Default deny - must create policies
CREATE POLICY "Users can view own profile"
  ON public.profiles
  FOR SELECT
  USING (auth.uid() = id);

Common RLS Policies

-- Public read
CREATE POLICY "Public read access"
  ON public.posts FOR SELECT
  USING (true);

-- Authenticated users only
CREATE POLICY "Authenticated users can insert"
  ON public.posts FOR INSERT
  WITH CHECK (auth.role() = 'authenticated');

-- Owner access
CREATE POLICY "Users can update own records"
  ON public.posts FOR UPDATE
  USING (auth.uid() = user_id);

-- Admin access (using custom claim)
CREATE POLICY "Admins have full access"
  ON public.posts FOR ALL
  USING (auth.jwt() ->> 'role' = 'admin');

Link to auth.users

-- Profile table linked to auth
CREATE TABLE public.profiles (
  id UUID PRIMARY KEY REFERENCES auth.users(id) ON DELETE CASCADE,
  username TEXT UNIQUE NOT NULL,
  avatar_url TEXT,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

-- Auto-create profile on signup
CREATE OR REPLACE FUNCTION public.handle_new_user()
RETURNS TRIGGER AS $$
BEGIN
  INSERT INTO public.profiles (id, username)
  VALUES (NEW.id, NEW.email);
  RETURN NEW;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

CREATE TRIGGER on_auth_user_created
  AFTER INSERT ON auth.users
  FOR EACH ROW EXECUTE FUNCTION public.handle_new_user();

Seed Data

supabase/seed.sql

-- Runs on `supabase db reset`
-- Use ON CONFLICT for idempotency

INSERT INTO public.profiles (id, username, avatar_url)
VALUES
  ('d0e1f2a3-b4c5-6d7e-8f9a-0b1c2d3e4f5a', 'testuser', null),
  ('a1b2c3d4-e5f6-7a8b-9c0d-1e2f3a4b5c6d', 'admin', null)
ON CONFLICT (id) DO NOTHING;

Environment Variables

Required Variables

# Public (safe for client-side)
SUPABASE_URL=https://xxxxx.supabase.co
SUPABASE_ANON_KEY=eyJ...

# Private (server-side only - NEVER expose)
SUPABASE_SERVICE_ROLE_KEY=eyJ...
DATABASE_URL=postgresql://postgres.[ref]:[password]@aws-0-region.pooler.supabase.com:6543/postgres

Local vs Production

# .env.local (local development)
SUPABASE_URL=http://localhost:54321
SUPABASE_ANON_KEY=<from supabase start>
DATABASE_URL=postgresql://postgres:postgres@localhost:54322/postgres

# .env.production (remote)
SUPABASE_URL=https://xxxxx.supabase.co
SUPABASE_ANON_KEY=<from dashboard>
DATABASE_URL=<connection pooler URL>

Connection Pooling

# Transaction mode (recommended for serverless)
# Add ?pgbouncer=true to URL
DATABASE_URL=postgresql://...@pooler.supabase.com:6543/postgres?pgbouncer=true

# Session mode (for migrations, long transactions)
DATABASE_URL=postgresql://...@pooler.supabase.com:5432/postgres

Edge Functions

Create Function

supabase functions new hello-world

Basic Structure

// supabase/functions/hello-world/index.ts
import { serve } from 'https://deno.land/std@0.168.0/http/server.ts';

serve(async (req) => {
  const { name } = await req.json();

  return new Response(
    JSON.stringify({ message: `Hello ${name}!` }),
    { headers: { 'Content-Type': 'application/json' } }
  );
});

With Auth Context

import { serve } from 'https://deno.land/std@0.168.0/http/server.ts';
import { createClient } from 'https://esm.sh/@supabase/supabase-js@2';

serve(async (req) => {
  const supabase = createClient(
    Deno.env.get('SUPABASE_URL') ?? '',
    Deno.env.get('SUPABASE_ANON_KEY') ?? '',
    {
      global: {
        headers: { Authorization: req.headers.get('Authorization')! },
      },
    }
  );

  const { data: { user } } = await supabase.auth.getUser();

  if (!user) {
    return new Response('Unauthorized', { status: 401 });
  }

  return new Response(JSON.stringify({ user_id: user.id }));
});

Deploy

# Serve locally
supabase functions serve

# Deploy single function
supabase functions deploy hello-world

# Deploy all
supabase functions deploy

Storage

Create Bucket (in migration)

INSERT INTO storage.buckets (id, name, public)
VALUES ('avatars', 'avatars', true);

-- Storage policies
CREATE POLICY "Avatar images are publicly accessible"
  ON storage.objects FOR SELECT
  USING (bucket_id = 'avatars');

CREATE POLICY "Users can upload own avatar"
  ON storage.objects FOR INSERT
  WITH CHECK (
    bucket_id = 'avatars' AND
    auth.uid()::text = (storage.foldername(name))[1]
  );

CLI Quick Reference

# Lifecycle
supabase start                   # Start local stack
supabase stop                    # Stop local stack
supabase status                  # Show status & credentials

# Database
supabase db reset                # Reset + migrations + seed
supabase db push                 # Push to remote
supabase db pull                 # Pull remote schema
supabase db diff -f <name>       # Generate migration from diff
supabase db lint                 # Check for issues

# Migrations
supabase migration new <name>    # Create migration
supabase migration list          # List migrations
supabase migration up            # Apply pending (remote)

# Functions
supabase functions new <name>    # Create function
supabase functions serve         # Local dev
supabase functions deploy        # Deploy all

# Types
supabase gen types typescript --local > types/database.ts

# Project