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Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
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AdminClient::describeConfigs
api takes a Collection
of ConfigResource
objects as argument to get all the configurations of the entities specified. Here is the api signature:
DescribeConfigsResult describeConfigs(Collection<ConfigResource> resources, DescribeConfigsOptions options);
The ConfigResource
class is made up of two fields, name (“topic-1”, “broker-1” etc) and type (BROKER, TOPIC etc) of entity.
This admin api in turn call DescribeConfigsRequest
kafka api to get the configuration for specified entities. DescribeConfigsRequest
api takes a collection of DescribeConfigsResource
objects to specify entities whose configuration needs to be fetched. So to make this Kafka API call, AdminClient::describeConfigs
converts ConfigResource
collection passed to it to a DescribeConfigsResource
collection. In addition to name and type of entity whose configuration to get, Kafka DescribeConfigsResource
structure also lets users provide ConfigurationKeys
, a list of String, which allows users to specify only the configurations that they are interested in. As this information isn’t present in the ConfigResource
class, it is set to null
when DescribeConfigsResource
object is created from it. Here is the code doing this (kafka/KafkaAdminClient.java at b38f6ba5cc989702180f5d5f8e55ba20444ea884 · apache/kafka )
Code Block |
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.map(config ->
new DescribeConfigsRequestData.DescribeConfigsResource()
.setResourceName(config.name())
.setResourceType(config.type().id())
.setConfigurationKeys(null)) |
This means that all configurations of all the entities specified are returned by Kafka. Then the user of the AdminClient::describeConfigs
iterates over the returned list and filters out the configuration 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 for large clusters where to fetch one configuration of all topics, we need to fetch all configuration of all topics, which can result in huge response.
This is also a usability issue when running kafka-configs
command which returns all configurations and then user need to either scan or filter for property that they are interested in.
We need to add same ConfigurationKeys
parameter that DescribeConfigsResource
takes to AdminClient’s ConfigResource
class to bring it to parity with DescribeConfigsResource
and allow AdminClient’s users to specify configuration keys that they are interested in.
In addition we need to add same option to kafka-configs
command line utility so that users of the tool don’t need to fetch all configurations when they are interested in only a few of them.
Public Interfaces
Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.
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