1. Introduction

Brief Explanation of the Tutorial's Goal

This tutorial aims to provide an understanding of how to create Firebase Security Rules for anonymous users. By the end of the tutorial, you will be able to set up security rules that allow access to specific resources in your application for users not logged in.

What the User Will Learn

• Understanding Firebase Security Rules
• Writing Security Rules for anonymous users

Prerequisites

• Basic understanding of Firebase and its features
• Firebase project setup

2. Step-by-Step Guide

Understanding Firebase Security Rules

Firebase Security Rules stand as the guard between Firebase services like Cloud Firestore, Firebase Storage, and the users of your app. They use expressions to determine whether to allow or deny requests to read and write data.

Writing Security Rules for anonymous users

In Firebase, anonymous users are treated as authenticated users with a unique user ID. Therefore, we can use the request.auth.uid property in our rules to identify anonymous users and restrict or allow access to our data accordingly.

3. Code Examples

Example 1: Allowing anonymous users to read data

service cloud.firestore {
  match /databases/{database}/documents {
    // Match any document in the 'public' collection
    match /public/{document=**} {
      allow read: if request.auth != null;
    }
  }
}

In this example, we're allowing any authenticated user (including anonymous users) to read data from the 'public' collection. The request.auth != null condition checks if a user is authenticated.

Example 2: Restricting write access to non-anonymous users

service cloud.firestore {
  match /databases/{database}/documents {
    match /private/{document=**} {
      allow write: if request.auth != null && request.auth.token.firebase.sign_in_provider != 'anonymous';
    }
  }
}

Here, we are allowing write access to the 'private' collection only to non-anonymous users. The request.auth.token.firebase.sign_in_provider != 'anonymous' condition checks if the user is not anonymous.

4. Summary

In this tutorial, we've learned about Firebase Security Rules and how to write rules for anonymous users. We've covered how to allow anonymous users to read data, and how to restrict write access to non-anonymous users.

For further learning, you can explore more complex rules and conditions, as well as how to debug and test Firebase Security Rules.

5. Practice Exercises

Exercise 1: Write rules to allow read access to all users, but write access only to anonymous users.

service cloud.firestore {
  match /databases/{database}/documents {
    match /any/{document=**} {
      allow read;
      allow write: if request.auth != null && request.auth.token.firebase.sign_in_provider == 'anonymous';
    }
  }
}

This rule allows read access to all users but restricts write access to anonymous users only.

Exercise 2: Write rules to restrict both read and write access to only non-anonymous users.

service cloud.firestore {
  match /databases/{database}/documents {
    match /exclusive/{document=**} {
      allow read, write: if request.auth != null && request.auth.token.firebase.sign_in_provider != 'anonymous';
    }
  }
}

This rule restricts both read and write access to non-anonymous users only.