Authorization with ACLs
Implement Access Control Lists (ACLs) on Kafka brokers to define fine-grained permissions for producers and consumers.
Authorization with ACLs is a free Advanced Spring Boot 4: Event-Driven Architecture (Kafka) lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Advanced Spring Boot 4: Event-Driven Architecture (Kafka) learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What are Kafka ACLs?
In our last lesson, we learned about authenticating with Kafka using SASL. But authentication just verifies who you are.
Authorization determines what you are allowed to do. This is where Access Control Lists (ACLs) come in.
Kafka ACLs provide fine-grained permissions, letting you control which users (or principals) can perform specific actions on Kafka resources.
The Core of Kafka Authorization
Authorization in Kafka revolves around three key concepts:
- Principal: The authenticated user or client attempting an action (e.g.,
User:Alice,User:ProducerApp). - Operation: The action being attempted (e.g.,
READ,WRITE,CREATE,DELETE). - Resource: The Kafka entity the operation is performed on (e.g., a specific topic, a consumer group).
ACLs define which principals can perform which operations on which resources.
Different Types of Kafka Resources
Kafka allows you to set permissions on several types of resources:
- Topic: For producing messages to or consuming from specific topics.
- Group: For managing consumer group memberships and offset commits.
- Cluster: For cluster-wide operations like describing brokers or creating topics.
- TransactionalId: For using Kafka transactions.
- DelegationToken: For managing delegation tokens (advanced).
Most common are Topic, Group, and Cluster resources.
ACL Syntax with `kafka-acls.sh`
ACLs are typically managed using the kafka-acls.sh command-line tool. You'll specify the principal, operation, and resource.
Here's a basic structure:
kafka-acls.sh --authorizer-properties ... \
--add --allow-principal 'User:Alice' \
--operation Read --topic 'my-topic'This grants User:Alice permission to Read from my-topic.
ACLs for a Kafka Producer
A Kafka producer needs permissions to:
- Write messages: To a specific topic.
- Describe the cluster: To discover broker metadata.
Example commands to grant these permissions for a producer named User:ProducerApp on topic orders:
kafka-acls.sh --add --allow-principal 'User:ProducerApp' --operation Write --topic 'orders' --authorizer-properties ...
kafka-acls.sh --add --allow-principal 'User:ProducerApp' --operation Describe --cluster --authorizer-properties ...Spring Producer & ACLs
This Spring Boot producer sends a message to my-secured-topic. For it to work, the principal associated with this application (e.g., User:my-producer via SASL) must have the necessary ACLs configured on the Kafka broker.
Specifically, it needs WRITE permission on the topic and DESCRIBE permission on the cluster resource.
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class KafkaProducerAclApp {
public static void main(String[] args) {
SpringApplication.run(KafkaProducerAclApp.class, args);
}
@Bean
public CommandLineRunner runner(KafkaTemplate<String, String> kafkaTemplate) {
return args -> {
String topic = "my-secured-topic";
String message = "Hello from secured producer!";
kafkaTemplate.send(topic, message);
System.out.println("Sent message: '" + message + "' to topic: '" + topic + "'");
System.out.println("Check Kafka broker logs for successful message receipt.");
};
}
}ACLs for a Kafka Consumer
A Kafka consumer needs permissions to:
- Read messages: From a specific topic.
- Read from its consumer group: To manage offsets and join the group.
- Describe the cluster: Like producers, for metadata.
Example commands for User:ConsumerApp on topic payments and group payment-processors:
kafka-acls.sh --add --allow-principal 'User:ConsumerApp' --operation Read --topic 'payments' --authorizer-properties ...
kafka-acls.sh --add --allow-principal 'User:ConsumerApp' --operation Read --group 'payment-processors' --authorizer-properties ...
kafka-acls.sh --add --allow-principal 'User:ConsumerApp' --operation Describe --cluster --authorizer-properties ...Spring Consumer & ACLs
This Spring Boot consumer listens to my-secured-topic as part of my-secured-group. Its associated principal (e.g., User:my-consumer) needs specific ACLs.
It requires READ permission on the topic, READ permission on the consumer group, and DESCRIBE permission on the cluster resource.
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.annotation.KafkaListener;
@SpringBootApplication
public class KafkaConsumerAclApp {
public static void main(String[] args) {
SpringApplication.run(KafkaConsumerAclApp.class, args);
}
@KafkaListener(topics = "my-secured-topic", groupId = "my-secured-group")
public void listen(String message) {
System.out.println("Received secured message: " + message);
}
}Listing & Revoking ACLs
It's important to manage ACLs effectively. You can list all ACLs or specific ones:
kafka-acls.sh --list --topic 'my-topic' --authorizer-properties ...To remove an ACL, use the --remove flag instead of --add, specifying the exact ACL you wish to revoke:
kafka-acls.sh --remove --allow-principal 'User:Alice' --operation Read --topic 'my-topic' --authorizer-properties ...Regularly review and remove unnecessary permissions for security best practices.
ACLs Quick Check
Which of the following permissions are typically required for a Kafka consumer to successfully read messages from a topic and join a consumer group?
Recap: Securing with ACLs
Great job! You've learned how Kafka's authorization works using Access Control Lists (ACLs).
- ACLs define who (principal) can do what (operation) on where (resource).
- Key resources include topics, consumer groups, and the cluster itself.
- You use
kafka-acls.shto manage these permissions on the broker. - Spring Boot Kafka applications implicitly rely on these ACLs being in place for their authenticated principals.
Next, we'll explore how to encrypt data in transit using SSL/TLS.
Frequently asked questions
Is the “Authorization with ACLs” lesson free?
Yes — the full text of “Authorization with ACLs” is free to read here on the web, and the Advanced Spring Boot 4: Event-Driven Architecture (Kafka) course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Advanced Spring Boot 4: Event-Driven Architecture (Kafka) course, upgrade to CoddyKit PRO.
What will I learn in “Authorization with ACLs”?
Implement Access Control Lists (ACLs) on Kafka brokers to define fine-grained permissions for producers and consumers. You practise Advanced Spring Boot 4: Event-Driven Architecture (Kafka) with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Advanced Spring Boot 4: Event-Driven Architecture (Kafka)?
No prior experience is required. Advanced Spring Boot 4: Event-Driven Architecture (Kafka) on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Authorization with ACLs” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Advanced Spring Boot 4: Event-Driven Architecture (Kafka) lesson?
Yes. Every Advanced Spring Boot 4: Event-Driven Architecture (Kafka) lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Authentication with SASL
- Authorization with ACLs
- Encryption with SSL/TLS
- Auditing and Securing Schema Registry Access