[KAFKA-13517] Update Admin::describeConfigs to allow fetching specific configurations

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.8.1, 3.0.0
• Component/s: clients
• Assignee: Vikas Singh
• Reporter: Vikas Singh
• Created: 08/Dec/21 05:01
• Updated: 21/Feb/22 07:17

Description

A list of ConfigResource class is passed as argument to AdminClient::describeConfigs api to indicate configuration of the entities to fetch. The ConfigResource class is made up of two fields, name and type of entity. Kafka returns all configurations for the entities provided to the admin client api.

This admin api in turn uses DescribeConfigsRequest kafka api to get the configuration for the entities in question. In addition to name and type of entity whose configuration to get, Kafka DescribeConfigsResource structure also lets users provide ConfigurationKeys list, which allows users to fetch only the configurations that are needed.

However, this field isn't exposed in the ConfigResource class that is used by AdminClient, so users of AdminClient have no way to ask for specific configuration. The API always returns all configurations. Then the user of the AdminClient::describeConfigs go over the returned list and filter out the config keys that they are interested in.

This results in boilerplate code for all users of AdminClient::describeConfigs api, in addition to  being wasteful use of resource. It becomes painful in large cluster case where to fetch one configuration of all topics, we need to fetch all configuration of all topics, which can be huge in size. 

Creating this Jira to track changes proposed in KIP-823: https://confluentinc.atlassian.net/wiki/spaces/~953215099/pages/2707357918/KIP+Admin+describeConfigs+should+allow+fetching+specific+configurations

Issue Links

• links to: GitHub Pull Request #11580