Status

Current state:  Under DiscussionAccepted

Discussion thread: TBD Here

JIRA: 

Released: 2.3.0

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

When consumer subscribes to a non-existent topic, it does not have control over whether the topic is automatically created or not. We have the broker configuration allow.auto.create.

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topics that controls topic auto-creation globally. If there is a lag between the consumers and producers starting up, we usually do not want the consumer to be able to automatically create the topic as this will use the default number of partitions and replication factor. Consumers should thus have the ability to be able to disable auto topic creation, if needed.

To work around the lack of such a configuration, consumers currently avoid subscribing to specific topics and use regex-based subscription instead, like in Streams. This is not optimal as it means consumers will request for and receive metadata for all topics and partitions in the cluster, which could be large.

Public Interfaces

We will add a new consumer configuration auto.create.topics.enable which is similar in spirit to its broker counterpart. If set to false, the topic being subscribed to will not be auto-created, regardless of what this configuration is set to on the broker.:

Configuration Name: allow.auto.create.topics.enable

Type: BOOLEAN
Explanation: This configuration controls whether the topic is automatically created when subscribing to a non-existent topic. This configuration is only applicable with 0.11 or higher versions of the broker. A topic will be auto-created only if this configuration as well the corresponding server-side configuration are both set to trueis set to true and auto-topic creation is enabled on the broker using auto.create.topics.enable; otherwise auto-topic creation is not permitted. This configuration must be set to true when using brokers older than 0.11.
Default Value: TRUE
Priority: MEDIUM

Proposed Changes

Whether the topic should be auto-created will be included in MetadataRequest sent by the consumer. In Kafka 0.11.0, MetadataRequest v4 had earlier introduced a way to specify if a topic should be auto-created when requesting metadata for specific topics.

If the broker is old and does not support v4, we will fallback to the default behavior of not specifying auto topic creation; the broker configuration will then control whether we automatically create topics or notolder than 0.11.0, allow.auto.create.topics must be set to true. If set to false in this case, the consumer will throw an InvalidConfigurationException at run-time. Specifically, the exception will be thrown on calling KafkaConsumer#poll after subscribing to a non-existent topic.

Compatibility, Deprecation, and Migration Plan

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