Access Control Lists (ACLs) in Redis provide a way to manage and control access to the Redis server. ACLs allow you to define which commands and keys a user can access, enhancing the security and manageability of your Redis instance. This section will cover the basics of ACLs, how to configure them, and practical examples to help you understand their usage.

1. Users: Redis allows you to create multiple users, each with specific permissions.
2. Rules: Each user can have a set of rules that define what commands and keys they can access.
3. Authentication: Users must authenticate themselves to access the Redis server.

To create a new user, you use the ACL SETUSER command. Here’s an example:

Explanation:

• alice: The username.
• on: Enables the user.
• >password: Sets the password for the user.
• ~*: Allows access to all keys.
• +@all: Grants all command permissions.

You can modify user permissions using the ACL SETUSER command. For example, to restrict a user to only read operations:

Explanation:

• +@read: Grants read command permissions.
• -@write: Denies write command permissions.

To list all users and their permissions, use the ACL LIST command:

To delete a user, use the ACL DELUSER command:

1. Create a user named readonly with read-only access:

   ACL SETUSER readonly on >readonlypassword ~* +@read -@write
   

2. Authenticate as the readonly user:

   AUTH readonly readonlypassword
   

3. Try to perform a write operation (this should fail):

   SET key1 value1
   

   Expected output:

   (error) NOPERM this user has no permissions to run the 'set' command
   

4. Perform a read operation (this should succeed):

   GET key1
   

   Expected output:

   (nil)
   

1. Create a user named limited with access to keys starting with prefix::

   ACL SETUSER limited on >limitedpassword ~prefix:* +@all
   

2. Authenticate as the limited user:

   AUTH limited limitedpassword
   

3. Try to access a key outside the allowed prefix (this should fail):

   GET otherkey
   

   Expected output:

   (error) NOPERM this user has no permissions to access one of the keys used as arguments
   

4. Access a key within the allowed prefix (this should succeed):

   SET prefix:key1 value1
   

   Expected output:

   OK
   

• Forgetting to Enable the User: Ensure you use the on keyword to enable the user.
• Misconfiguring Permissions: Double-check the permissions you set to avoid unintended access.
• Strong Passwords: Always use strong, unique passwords for each user to enhance security.

In this section, we covered the basics of Access Control Lists (ACLs) in Redis, including how to create and manage users, set permissions, and practical examples of configuring ACLs. ACLs are a powerful feature to enhance the security and manageability of your Redis instance by controlling access at a granular level. In the next section, we will delve into Redis Security Best Practices to further secure your Redis deployment.