Mirror Maker 2: Why Your Topics Aren't Auto-Creating
Mirror Maker 2 (MM2) is a powerful tool for replicating Kafka topics from one cluster to another. However, you might encounter situations where MM2 doesn't automatically create topics in the target cluster, leading to unexpected behavior. Let's break down this common problem and explore solutions.
Scenario: You've set up MM2 to replicate topics from your source Kafka cluster to your target cluster. You create a new topic on the source cluster, but it doesn't appear on the target cluster.
Original Code (Example):
# mirror-maker.properties
bootstrap.servers=source-kafka:9092
target.bootstrap.servers=target-kafka:9092
# ...other configurations...
The Root of the Problem:
MM2 doesn't automatically create topics in the target cluster by default. It relies on a mechanism called "topic whitelisting" to ensure controlled replication. This means you need to explicitly configure which topics MM2 should replicate.
Understanding Topic Whitelisting:
Topic whitelisting in MM2 ensures that only specific topics are replicated. This approach helps you:
- Control Replication: Prevent unwanted topics from being replicated.
- Optimize Resources: Avoid replicating unnecessary topics, saving resources on both clusters.
- Security: Enforce a controlled replication process for sensitive topics.
Troubleshooting & Solutions:
-
Check Topic Whitelist: Ensure the target topic is explicitly listed in the
replication.topic.listconfiguration within your MM2 properties file.replication.topic.list=topic1,topic2,new-topic -
Automatic Topic Creation: If you require automatic topic creation, you can use the
auto.create.topics.enableproperty within your MM2 configuration. Setting this totruewill enable automatic topic creation on the target cluster.auto.create.topics.enable=trueCaution: This option allows all topics from the source cluster to be replicated to the target cluster. Carefully consider the implications of this approach on your target cluster resources and security.
-
Topic Replication Pattern: Ensure your topic names match between the source and target clusters. Any discrepancies will prevent successful replication.
Additional Tips:
- Enable Logging: Set appropriate logging levels in your MM2 configuration to gain insight into replication errors and potential issues.
- Check Source Cluster: Verify that the new topic is properly created and available in your source Kafka cluster.
- Use a Topic Registry: Tools like Schema Registry or Confluent Schema Registry can automatically create and manage topic schema definitions for efficient data replication.
Conclusion:
Understanding topic whitelisting and its role in MM2 is crucial to prevent unexpected behaviors. By properly configuring your MM2 properties and employing best practices, you can seamlessly replicate Kafka topics and build robust, scalable data pipelines.
Further Resources:
Remember, by understanding these configurations and best practices, you can leverage the power of MM2 to reliably replicate your Kafka topics, enhancing your data infrastructure's performance and scalability.
