Skip to main content
Learn how to view and modify topic configurations using kafka-configs in 10 minutes While broker-level defaults work for most topics, some require customization. The kafka-configs CLI tool lets you override configurations for specific topics without affecting the cluster defaults. What you’ll learn:
  • How to view current topic configurations
  • How to add configuration overrides with kafka-configs
  • How to remove configuration overrides
  • Common configurations that need per-topic tuning

​
Common topic configuration overrides

ConfigurationDefaultDescription
min.insync.replicas1Minimum ISRs for acks=all
retention.ms7 daysData retention time
retention.bytes-1 (unlimited)Maximum partition size
cleanup.policydeletedelete or compact
max.message.bytes1 MBMaximum message size
compression.typeproducerBroker-side compression
The complete list of topic configurations can be found in the Kafka documentation.

​
Override topic configuration defaults

The kafka-configs CLI tool allows you to set, view, and delete configurations for topics, brokers, and other entities without restarting the cluster. Use CLI commands with appropriate extensions for your platform (e.g., kafka-configs.bat for Windows, kafka-configs.sh for Linux). Let’s change the min.insync.replicas configuration of a topic. The default broker value is 1, but for production with replication factor of 3, a value of 2 is recommended. See min.insync.replicas for details. Before running Kafka CLIs make sure that you have started Kafka successfully. First, create a topic named configured-topic with 3 partitions and a replication factor of 1, using Kafka topics CLI, kafka-topics 
kafka-topics --bootstrap-server localhost:9092 --create --topic configured-topic --partitions 3 --replication-factor 1
Describe the topic to check if there are any configuration override set for this topic. 
kafka-topics --bootstrap-server localhost:9092 --describe --topic configured-topic

Topic: configured-topic	TopicId: CDU7SBxBQ1mzJGnuH68-cQ	PartitionCount: 3	ReplicationFactor: 1	Configs:
	Topic: configured-topic	Partition: 0	Leader: 2	Replicas: 2	Isr: 2
	Topic: configured-topic	Partition: 1	Leader: 3	Replicas: 3	Isr: 3
	Topic: configured-topic	Partition: 2	Leader: 1	Replicas: 1	Isr: 1
There is no configuration override set. Set the min.insync.replicas value for the topic configured-topic to 2 
kafka-configs --bootstrap-server localhost:9092 --alter --entity-type topics --entity-name configured-topic --add-config min.insync.replicas=2
And describe the topic again 
kafka-topics --bootstrap-server localhost:9092 --describe --topic configured-topic

Topic: configured-topic	TopicId: CDU7SBxBQ1mzJGnuH68-cQ	PartitionCount: 3	ReplicationFactor: 1	Configs: min.insync.replicas=2
	Topic: configured-topic	Partition: 0	Leader: 2	Replicas: 2	Isr: 2
	Topic: configured-topic	Partition: 1	Leader: 3	Replicas: 3	Isr: 3
	Topic: configured-topic	Partition: 2	Leader: 1	Replicas: 1	Isr: 1
Now, you can see there is a topic configuration override set (at the right side of the output) - min.insync.replicas=2. You can delete the configuration override by passing --delete-config in place of the --add-config flag. 
kafka-configs --bootstrap-server localhost:9092 --alter --entity-type topics --entity-name configured-topic --delete-config min.insync.replicas
Describe the topic to make sure the configuration override has been removed.

​
Other common configuration changes

​
Set retention to 30 days

kafka-configs --bootstrap-server localhost:9092 --alter \
  --entity-type topics --entity-name configured-topic \
  --add-config retention.ms=2592000000

​
Enable log compaction

kafka-configs --bootstrap-server localhost:9092 --alter \
  --entity-type topics --entity-name configured-topic \
  --add-config cleanup.policy=compact

​
Set multiple configurations at once

kafka-configs --bootstrap-server localhost:9092 --alter \
  --entity-type topics --entity-name configured-topic \
  --add-config min.insync.replicas=2,retention.ms=604800000
Some configuration changes take effect immediately, while others only apply to new data. Test configuration changes in a non-production environment first.
See it in practice with ConduktorConduktor Console provides a visual interface for viewing and modifying topic configurations. See all overrides at a glance and make changes without memorizing CLI syntax.

​
Next steps