Confluent Cloud Broker and Topic Configuration Settings

This topic describes the default Kafka topic and broker configurations in Confluent Cloud. For a complete description of all Kafka broker and topic configurations, see Confluent Platform Configuration Reference.

Important

  • Dedicated clusters can be enabled to allow some cluster settings to be changed
  • You cannot edit cluster settings on Confluent Cloud on Basic or Standard clusters, but you can edit certain topic configurations after a topic has been created.
  • You cannot access internal Kafka topics. For example, the internal topic __consumer_offsets is not accessible. Topics that are not accessible do not count toward partition limits or partition billing charges. Topics created by managed Connectors and ksqlDB are accessible.
  • After a topic has been created, you cannot edit the cleanup.policy from delete to compact.
Parameter Name Default Editable
auto.create.topics.enable false Yes, on Dedicated clusters only
cleanup.policy delete Yes
compression.type producer No
default.replication.factor 3 No
delete.retention.ms 86400000 Yes
file.delete.delay.ms 60000 No
flush.messages 9223372036854775807 No
flush.ms 9223372036854775807 No
index.interval.bytes 4096 No
log.message.timestamp.type CreateTime Yes
max.compaction.lag.ms 9223372036854775807 No
message.downconversion.enable true No
message.format.version 2.3-IV1 No
message.max.bytes 2097164 Yes
message.timestamp.difference.max.ms 9223372036854775807 Yes
message.timestamp.type CreateTime Yes
min.cleanable.dirty.ratio 0.5 No
min.compaction.lag.ms 0 Yes
min.insync.replicas 2 Yes
num.partitions 6 Yes, via Admin API
offsets.retention.minutes 10080 No
preallocate false No
retention.bytes -1 Yes
retention.ms null Yes
segment.index.bytes 1073741824 No
segment.jitter.ms 0 No
segment.ms 604800000 Yes
unclean.leader.election.enable false No

Custom settings for Dedicated clusters

Important

By default the following settings cannot be modified. The ability to modify some cluster settings is currently in limited Early Access. You can submit a support request to enable modification of these settings on a per-cluster basis. Your support ticket must include the cluster ID, which you can find on the Cluster Settings page in the Confluent Cloud UI. After support confirms that your cluster has been enabled, you will be able to use the commands below to modify the listed cluster settings. These settings cannot be modified on Basic or Standard clusters.

The following Dedicated cluster settings can be modified using the Kafka CLI:

  • Enable automatic topic creation (auto.create.topics.enable)

    kafka-configs --bootstrap-server <bootstrap> --command-config config.properties --entity-type brokers --entity-default --alter --add-config auto.create.topics.enable=true
    

    For more information about why the auto.create.topics.enable parameter is disabled by default in Confluent Cloud, see this blog post.

  • Restrict allowed SSL cipher suites (ssl.cipher.suites)

    kafka-configs --bootstrap-server <bootstrap> --command-config config.properties --entity-type brokers --entity-default --alter --add-config ssl.cipher.suites=<list>
    

    The valid list of ciphers includes:

    TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
    TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
    TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
    TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
    TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
    
  • Set the default number of partitions for new topics (num.partitions)

    kafka-configs --bootstrap-server <bootstrap> --config-file <auth-configs> --entity-type brokers --entity-default --alter --add-config num.partitions=<int>
    
  • Set the default log retention time for new topics (log.retention.ms)

    kafka-configs --bootstrap-server <bootstrap> --config-file <auth-configs> --entity-type brokers --entity-default --alter --add-config log.retention.ms=<int>
    

Changes to the above config setting are dynamically applied to your Confluent Cloud cluster.