20 - Firestore Security Rules in Firebase

Introduction

Firestore Security Rules are a critical aspect of Firebase, allowing developers to define access control and validation rules for their Cloud Firestore database. These rules determine who can read or write data in the database, ensuring data security and integrity.

Understanding Firestore Security Rules

Firestore Security Rules operate on the principle of role-based access control (RBAC), defining access permissions based on roles and conditions. Developers can set rules to control access at the collection or document level, specifying read, write, or other operations.

Defining Security Rules

To define security rules, developers use a declarative language called Firebase Security Rules Language (FSL). These rules consist of match statements that determine the conditions for accessing data and the actions allowed based on those conditions.

Example of Security Rules


rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow read: if request.auth.uid == userId;
      allow write: if request.auth.uid == userId && request.resource.data.name != "";
    }
  }
}

In this example, the rules allow users to read their own data (matching the document path) and write data only if the user is authenticated (request.auth.uid is their own user ID) and the data being written contains a non-empty “name” field.

Common Security Rule Patterns

1. Allowing Authenticated Users Only: Restrict access to authenticated users.


allow read, write: if request.auth != null;

2. Limiting Write Access: Limit write access based on specific conditions.


allow write: if request.resource.data.someField == "allowedValue";

3. Role-Based Access Control: Define different access levels for users based on their roles.


allow write: if get(/databases/$(database)/documents/users/$(request.auth.uid)).data.role == "admin";

Testing Security Rules

Firebase provides tools like the Firebase Security Rules Simulator to test and validate security rules before deploying them to your production environment. This helps ensure that the rules function as intended and provide the desired level of security.

Best Practices for Firestore Security Rules

1. Regularly review and update security rules to adapt to changes in your application’s requirements.

2. Minimize access by following the principle of least privilege, allowing users to access only what is necessary for their role or task.

3. Thoroughly test security rules to identify and address any potential security vulnerabilities.

20 – Firestore Security Rules in Firebase