Supabase Storage Objects Owner Changed: A Deep Dive

Introduction: The Mysterious Shift in storage.objects Ownership

Have you ever encountered a situation where something that used to work flawlessly suddenly throws an error, leaving you scratching your head? That's precisely what happened to one of our users when they tried to script Row Level Security (RLS) policies for the storage.objects table in Supabase. Previously, these policies could be created seamlessly by the postgres user, ensuring a consistent setup across different environments. However, a recent attempt to run the same migration script resulted in an error message stating that the postgres user must be the owner of the table, which it apparently was not. This shift in ownership, though perhaps an intentional decision by the Supabase team, has significant implications for developers relying on programmatic RLS policy management. In this article, we'll delve into this issue, explore its potential causes, discuss the impact on development workflows, and look at how you might navigate this change to maintain your application's security and deployment consistency.

Understanding Row Level Security (RLS) and storage.objects

Before we dive deeper into the ownership change, let's briefly touch upon Row Level Security (RLS) and the storage.objects table. RLS is a powerful feature in PostgreSQL that allows you to control, on a row-by-row basis, which users can access or modify data within a table. This granular control is crucial for building secure applications where different users or roles should only see or interact with specific data. The storage.objects table, within the Supabase ecosystem, is central to its file storage service. It contains metadata about all the files uploaded to your Supabase project, such as their names, sizes, content types, and where they are stored. Securing this table is paramount, as it dictates who can upload, download, list, or delete files. Traditionally, developers have used SQL scripts to define and manage RLS policies, often automating this process as part of their database migrations. This approach ensures that security rules are version-controlled and applied consistently across development, staging, and production environments. The ability to script these policies as the postgres user was a convenient way to manage them without needing specific user permissions for each policy creation, simplifying deployment pipelines and reducing the potential for human error. The change in ownership of the storage.objects table directly impacts this workflow, as the postgres user no longer has the necessary privileges to alter policies on this specific table, forcing a re-evaluation of how RLS policies are managed.

The Bug Report: postgres User Denied Policy Creation

The core of the issue lies in a seemingly simple yet impactful change: the owner of the storage.objects table has been altered. Our user, who had a robust system for scripting RLS policies to apply to storage.objects across multiple environments, discovered this when their migration script failed. The script, which had worked flawlessly in several environments just a few months prior, now produced an error indicating that the postgres user, despite being a superuser, was not the owner of storage.objects and therefore could not create RLS policies on it. This is particularly problematic because scripting RLS policies allows for automation, consistency, and version control. When these scripts break, it disrupts the deployment process and introduces friction into development workflows. The user expressed frustration, noting that while the Supabase UI does allow for policy creation, it's a manual process that is far from ideal for automated deployments. The desire is to manage database configurations, including security policies, through code and migrations, rather than relying on a graphical interface. This is a common practice in modern development to ensure that infrastructure and application configurations are reproducible and auditable. The inability to script these policies as the postgres user effectively removes a key piece of automation for Supabase users, forcing them to find alternative, potentially less efficient, methods for managing their storage security.

Reproducing the Issue: A Step-by-Step Example

To illustrate the problem clearly, let's walk through the steps that led to the error. The user provided a simplified SQL query that, when executed in a tool like pgAdmin, demonstrates the ownership conflict:

CREATE POLICY "x"
    ON storage.objects
    AS PERMISSIVE
    FOR SELECT
    TO authenticated
    USING (true)

This query is intended to create a permissive SELECT policy named "x" on the storage.objects table, allowing access to authenticated users under the condition USING (true), which essentially means anyone authenticated can select data. In a standard PostgreSQL setup, or in previous versions/configurations of Supabase, the postgres user would typically have the necessary privileges to create such a policy. However, when attempting to run this exact query using the postgres user in pgAdmin, the system now throws an error. The error message explicitly states that the postgres user must be the owner of the storage.objects table. This is a critical deviation from expected behavior. It's important to note that the user also mentioned that the same query does work when executed through the Supabase UI's SQL Editor. This suggests that the SQL Editor might be running the query with different elevated privileges or under a different context than a direct connection via pgAdmin using the postgres user. This discrepancy highlights a potential inconsistency in how privileges are handled or a deliberate restriction placed on direct user modifications of certain system tables like storage.objects outside of the Supabase platform's managed interfaces. The screenshot provided in the original bug report further solidifies this, showing the error message received when attempting the CREATE POLICY command.

Expected Behavior vs. Actual Behavior

The expected behavior in this scenario, based on prior experience and standard database practices, is that the CREATE POLICY statement should execute successfully. Developers anticipate being able to define and manage RLS policies programmatically, especially for critical tables like storage.objects, as part of their infrastructure-as-code or database migration strategies. This allows for a consistent, repeatable, and version-controlled approach to security configuration across all environments. The ability for the postgres user (or any user with sufficient administrative privileges) to create policies on system tables is fundamental to this automated workflow.

However, the actual behavior observed is a failure. The CREATE POLICY statement fails with an error message that the postgres user is not the owner of the storage.objects table and thus cannot create policies. This effectively blocks the automated, script-based creation of RLS policies for storage objects when using external tools like pgAdmin. This change forces developers to reconsider their deployment strategies. If programmatic creation is blocked, the alternative is manual intervention through the Supabase UI. While the UI is user-friendly for interactive tasks, it is not suitable for automated deployments. Manual policy creation is prone to errors, difficult to track in version control, and significantly slows down the deployment process, especially for projects with frequent updates or multiple environments. The discrepancy between running the query in pgAdmin versus the Supabase UI SQL Editor also raises questions about the underlying privilege model and how Supabase manages its internal tables and security configurations. This unexpected restriction disrupts established workflows and necessitates a careful examination of Supabase's internal architecture and recommended practices for managing storage security.

Potential Implications and Workarounds

This change in ownership and the subsequent inability to script RLS policies for storage.objects has several potential implications for Supabase users. Firstly, it disrupts automated deployment pipelines that rely on SQL migrations for setting up security rules. Developers who have automated their infrastructure-as-code deployments might find their processes breaking, requiring significant rework. Secondly, it introduces a potential inconsistency between different environments. If policies are managed manually in the UI for some environments and were previously scripted for others, maintaining a unified security posture becomes challenging. The reliance on manual UI adjustments also increases the risk of human error, which can have serious security consequences. For instance, forgetting to apply a critical policy in a production environment could leave sensitive data exposed.

While Supabase's intention might be to safeguard these critical tables from accidental misconfiguration by users, it inadvertently hinders established best practices for database management. The user suggested that the