Secure Your Supabase Data With Schema & RLS

In today's digital landscape, safeguarding user data is paramount. When building applications, especially those dealing with sensitive information like personal audio creations, implementing robust security measures from the get-go is not just a good idea – it's absolutely essential. This is where a well-designed database schema combined with powerful Row Level Security (RLS) policies in platforms like Supabase becomes your best friend. We're diving deep into how to architect your Supabase database to ensure users can only access *their own* data and audio, making your application secure by design. Let's explore the tables you'll need, the crucial RLS policies to implement, and how to secure your storage buckets.

Crafting Your Supabase Schema for Security

A strong foundation starts with a well-thought-out database schema. For our audio creation application, we need to meticulously define the tables that will hold user information, their secrets, settings, chat history, and the audio tracks themselves. Each table will be designed with specific relationships and constraints to enforce data integrity and security. The core idea is to link everything back to the authenticated user, ensuring that data is always associated with the correct individual. This approach prevents unauthorized access and makes it significantly harder for malicious actors to exploit vulnerabilities. We'll start by outlining the essential tables and their columns, focusing on how each piece contributes to the overall security posture of your application. Remember, *every column and relationship matters* when it comes to building a secure system. The primary key for most user-specific data will often be a `uuid` that directly references the authenticated user's ID from Supabase Auth, creating an unbreakable link. This is the cornerstone of our RLS strategy. We'll also implement `updated_at` triggers to keep track of changes, which is crucial for auditing and debugging, though not directly a security feature, it aids in maintaining a secure environment.

Essential Tables for Your Application

Let's break down the specific tables required to manage user data and audio creations securely. Each table is designed to store distinct pieces of information, all interconnected to maintain a clear ownership structure.

First, we have the `profiles` table. This table is fundamental as it stores basic user information tied directly to their authentication ID. The `id uuid primary key` column is a direct reference to the `auth.users.id`, ensuring each profile belongs to a unique authenticated user. We include `artist_name` for personalization, and `created_at` and `updated_at` timestamps for tracking record lifecycle. Next, consider the `user_secrets` table. This is where you'll store sensitive API keys or credentials for third-party services like OpenAI or ElevenLabs. The `user_id uuid primary key references profiles(id) on delete cascade` ensures that if a user's profile is deleted, their associated secrets are also automatically removed, maintaining data hygiene. Sensitive information like `openai_secret_id` and `elevenlabs_secret_id` are stored here, encrypted at rest by Supabase. The `created_at` and `updated_at` timestamps are again crucial for auditing. Similarly, the `user_settings` table holds user-specific configurations. This includes default models like `openai_model`, default settings for ElevenLabs (`eleven_music_defaults`), and default prompts (`prompt_defaults`). The `user_id uuid primary key references profiles(id) on delete cascade` establishes a strong link, ensuring settings are tied to the correct user. Defaults are provided to offer a seamless out-of-the-box experience, but the `jsonb` type allows for flexible and extensible settings as your application grows. The `created_at` and `updated_at` timestamps are vital for tracking any changes to user preferences. Moving on, the `chats` table is central to the conversation history feature. Each chat conversation is uniquely identified by `id uuid primary key default gen_random_uuid()`, and critically, it's linked to a user via `user_id uuid not null references profiles(id) on delete cascade`. This `user_id` is the linchpin for our RLS policies. We also store a `title` for easy reference and `created_at`, `updated_at` timestamps. The `chat_messages` table stores the actual messages within a chat. It has its own `id uuid primary key default gen_random_uuid()`, references its parent `chat_id uuid not null references chats(id) on delete cascade`, and includes fields for `role` (user, assistant, system), `content` (the message text), and potentially `draft_spec jsonb null` to store a snapshot of a draft track. The `created_at` timestamp is important for ordering messages. Finally, the `tracks` table holds the generated audio tracks. Each track has a `id uuid primary key default gen_random_uuid()`, is linked to a `chat_id uuid not null references chats(id) on delete cascade`, and most importantly, to the user via `user_id uuid not null references profiles(id) on delete cascade`. It includes fields for `title`, `description`, `final_prompt`, `metadata jsonb`, `length_ms`, `instrumental` flag, `status` (draft, generating, ready, failed), and `error jsonb`. The `storage_path text null` will hold the reference to the audio file in storage. This table is a prime candidate for strict RLS policies to ensure users can only access their own creations. The `created_at` and `updated_at` timestamps are essential here as well.

Implementing Row Level Security (RLS) Policies

With our schema defined, the next critical step is to implement Row Level Security (RLS) policies. RLS is a Supabase feature that allows you to control exactly who can read, write, update, or delete rows in your database tables, even down to the individual row level. This is the *most important* aspect of securing your user data. By default, Supabase tables are not secured, meaning any authenticated user can potentially access any data. We need to explicitly enable RLS on each table and then define granular policies. For the `profiles` table, RLS should be enabled, and the policy should allow a user to `SELECT` and `UPDATE` their own profile where `id = auth.uid()`. Inserts into this table are typically handled by server actions or triggers upon user sign-up to ensure data integrity and prevent unauthenticated insertions. For tables like `user_secrets` and `user_settings`, the policy is straightforward: only allow operations (`SELECT`, `INSERT`, `UPDATE`, `DELETE`) where the `user_id` column matches the currently authenticated user's ID (`auth.uid()`). This ensures that users cannot access or modify the sensitive secrets or settings of other users. When it comes to the `chats` table, the policy should restrict access to chats where `user_id = auth.uid()`. This means a user can only view, create, or delete their own chat conversations. For `chat_messages`, the policy is a bit more nuanced. Users should only be able to access messages that belong to *their* chats. This is achieved by joining the `chat_messages` table with the `chats` table and checking if `chats.user_id = auth.uid()`. This ensures that even if a user somehow knows a message ID, they can only access it if it's part of a chat they own. Finally, the `tracks` table requires similar strict policies. Users should only be able to `SELECT`, `UPDATE`, or `DELETE` tracks where `user_id = auth.uid()`. Additionally, to reinforce security and prevent potential bypasses, we also ensure that the `tracks.chat_id` belongs to a chat owned by the user by checking `chats.user_id = auth.uid()` through a join. This multi-layered approach provides robust security for user-generated content. Enabling RLS is done via `ALTER TABLE your_table_name ENABLE ROW LEVEL SECURITY;`, and policies are added using `CREATE POLICY policy_name ON your_table_name FOR operation USING (condition);`.

Policy Examples (SQL)

Here's a glimpse into how these RLS policies would look in SQL:

Profiles Table:

-- Enable RLS
ALTER TABLE profiles ENABLE ROW LEVEL SECURITY;
-- Allow users to see their own profile
CREATE POLICY "Users can view their own profile" ON profiles FOR SELECT USING (auth.uid() = id);
-- Allow users to update their own profile
CREATE POLICY "Users can update their own profile" ON profiles FOR UPDATE USING (auth.uid() = id);

User Secrets Table:

-- Enable RLS
ALTER TABLE user_secrets ENABLE ROW LEVEL SECURITY;
-- Allow users to access their own secrets
CREATE POLICY "Users can manage their own secrets" ON user_secrets FOR ALL USING (auth.uid() = user_id);

User Settings Table:

-- Enable RLS
ALTER TABLE user_settings ENABLE ROW LEVEL SECURITY;
-- Allow users to manage their own settings
CREATE POLICY "Users can manage their own settings" ON user_settings FOR ALL USING (auth.uid() = user_id);

Chats Table:

-- Enable RLS
ALTER TABLE chats ENABLE ROW LEVEL SECURITY;
-- Allow users to manage their own chats
CREATE POLICY "Users can manage their own chats" ON chats FOR ALL USING (auth.uid() = user_id);

Chat Messages Table:

-- Enable RLS
ALTER TABLE chat_messages ENABLE ROW LEVEL SECURITY;
-- Allow users to see messages from their chats
CREATE POLICY "Users can view messages from their chats" ON chat_messages FOR SELECT USING (
EXISTS (
SELECT 1
FROM chats
WHERE chats.id = chat_messages.chat_id
AND chats.user_id = auth.uid()
)
);
-- Allow users to insert new messages into their chats
CREATE POLICY "Users can insert messages into their chats" ON chat_messages FOR INSERT WITH CHECK (
EXISTS (
SELECT 1
FROM chats
WHERE chats.id = chat_messages.chat_id
AND chats.user_id = auth.uid()
)
);

Tracks Table:

-- Enable RLS
ALTER TABLE tracks ENABLE ROW LEVEL SECURITY;
-- Allow users to manage their own tracks
CREATE POLICY "Users can manage their own tracks" ON tracks FOR ALL USING (auth.uid() = user_id);
-- Ensure tracks belong to a chat owned by the user (redundant but good practice)
CREATE POLICY "Tracks must belong to user's chats" ON tracks FOR ALL USING (
EXISTS (
SELECT 1
FROM chats
WHERE chats.id = tracks.chat_id
AND chats.user_id = auth.uid()
)
);

These policies are the backbone of your application's security. They ensure that *no user can access or manipulate data that doesn't belong to them*, preventing common vulnerabilities like unauthorized data retrieval or modification. The use of `auth.uid()` is critical here, as it dynamically refers to the currently logged-in user's unique identifier provided by Supabase Auth. The `EXISTS` clause in policies for related tables, like `chat_messages` and `tracks`, is a powerful technique to enforce relationships and ensure data integrity across different tables. It verifies that the requested record is associated with a parent record that *also* belongs to the authenticated user. Implementing these policies systematically across all relevant tables creates a secure environment where data ownership is strictly enforced.

Securing Your Audio Storage

Beyond database security, protecting user-uploaded or generated files is equally important. For our application, the audio tracks need to be stored securely. Supabase Storage offers a robust solution for this. We'll create a private bucket named `tracks`. The key to securing these files lies in the object naming convention and associated storage policies. We'll adopt a structured object key format: `tracks/{user_id}/{chat_id}/{track_id}.mp3`. This hierarchical structure not only organizes files logically but also embeds the `user_id` directly into the path. This is crucial for implementing access control. Once the bucket is created and the object format is defined, we need to set up storage policies. These policies function similarly to RLS for your database tables. The core policy should allow read and write access *only* if the object name starts with `tracks/{auth.uid()}/`. This single policy effectively restricts users to accessing and modifying only their own files. Anyone attempting to access a file belonging to another user, even if they guess the UUIDs, will be denied access because their `auth.uid()` will not match the `user_id` embedded in the path. This approach leverages the user's authentication context directly within the storage policy, providing a seamless and secure way to manage user-generated content. To implement this, you would navigate to the Supabase Storage dashboard, create a new bucket named `tracks`, and then configure the policies. The policy would typically look something like: `allow read, write if request.path.startsWith("tracks/" .. auth.uid() .. "/")`.

Migration Files and Testing

To manage these database and storage configurations effectively, it's best practice to use migration files. We'll plan for three key migration files:

• `/supabase/migrations/0001_init.sql`: This file will handle the initial setup, including enabling necessary PostgreSQL extensions (like `uuid-ossp` for `gen_random_uuid()`) and creating all the tables defined earlier.
• `/supabase/migrations/0002_rls.sql`: This file will focus solely on enabling RLS on all tables and defining all the RLS policies we've discussed. Separating RLS makes it easier to review and manage security configurations.
• `/supabase/migrations/0003_storage.sql`: This file will cover the creation of the `tracks` storage bucket and the implementation of its associated access policies.

These migration files ensure that your database schema, RLS policies, and storage configurations are version-controlled and repeatable. This is invaluable for development, deployment, and disaster recovery. The