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Status

Current state: Under Discussion

Discussion thread: here TODO

JIRA: hereTODO

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

Motivation

Connect has a REST endpoint for Workers, which today have resources for managing "plugins" (class `ConnectorPluginsResource`) and "connectors" (class `ConnectorsResource`). The `plugins` resource is particularly useful to query the Connect cluster which connectors it has loaded to its plugin path ("GET /" endpoint). In reality, Connectors are just one type of plugin: Other types include Simple Message Transformations (SMTs), Converters, HeaderConverters, ConfigProviders, and RestExtensions (loaded by the "DelegatingClassLoader").

Since SMTs are a popular feature, and the current way to know which are loaded is to read the logs. In many cases, logs may be cleaned and a long-running server will have no way to conveniently reporting loaded SMTs.

This KIP will add HTTP endpoints for Transformations, Converters, HeaderConverters, ConfigProviders, and ConnectRestExtensions to Connect RestServers.

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.

A public interface is any change to the following:

• Binary log format

• The network protocol and api behavior

• Any class in the public packages under clientsConfiguration, especially client configuration

  • org/apache/kafka/common/serialization

  • org/apache/kafka/common

  • org/apache/kafka/common/errors

  • org/apache/kafka/clients/producer

  • org/apache/kafka/clients/consumer (eventually, once stable)

• Monitoring

• Command line tools and arguments

• Anything else that will likely break existing users in some way when they upgrade

Proposed Changes

Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

Compatibility, Deprecation, and Migration Plan

This is a simple addition, so no compatibility or migration issues. Existing APIs are intentionally left unaltered for simplicity.

We will need to update the docs.

Rejected Alternatives

Limiting scope of KIP to just SMTs

The scope could be limited to just adding HTTP Endpoints for just SMTs, which have the most pressing need. However, any design extending the current API to include SMTs would be designed to be elegantly extensible, and then most of the work to just include the other Plugin types is already done.

Updating existing endpoint for "GET /connector-plugins/" to include all plugins, as its name suggests

This strategy would break compatibility, and there are suitable alternatives without breaking changes.