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https://issues.apache.org/jira/browse/KAFKA-10816?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Egerton resolved KAFKA-10816.
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Fix Version/s: 3.9.0
Resolution: Done
> Connect REST API should have a resource that can be used as a readiness probe
> -----------------------------------------------------------------------------
>
> Key: KAFKA-10816
> URL: https://issues.apache.org/jira/browse/KAFKA-10816
> Project: Kafka
> Issue Type: Improvement
> Components: connect
> Reporter: Randall Hauch
> Assignee: Chris Egerton
> Priority: Major
> Fix For: 3.9.0
>
>
> There are a few ways to accurately detect whether a Connect worker is
> *completely* ready to process all REST requests:
> # Wait for {{Herder started}} in the Connect worker logs
> # Use the REST API to issue a request that will be completed only after the
> herder has started, such as {{GET /connectors/{name}/}} or {{GET
> /connectors/{name}/status}}.
> Other techniques can be used to detect other startup states, though none of
> these will guarantee that the worker has indeed completely started up and can
> process all REST requests:
> * {{GET /}} can be used to know when the REST server has started, but this
> may be before the worker has started completely and successfully.
> * {{GET /connectors}} can be used to know when the REST server has started,
> but this may be before the worker has started completely and successfully.
> And, for the distributed Connect worker, this may actually return an older
> list of connectors if the worker hasn't yet completely read through the
> internal config topic. It's also possible that this request returns even if
> the worker is having trouble reading from the internal config topic.
> * {{GET /connector-plugins}} can be used to know when the REST server has
> started, but this may be before the worker has started completely and
> successfully.
> The Connect REST API should have an endpoint that more obviously and more
> simply can be used as a readiness probe. This could be a new resource (e.g.,
> {{GET /status}}), though this would only work on newer Connect runtimes, and
> existing tooling, installations, and examples would have to be modified to
> take advantage of this feature (if it exists).
> Alternatively, we could make sure that the existing resources (e.g., {{GET
> /}} or {{GET /connectors}}) wait for the herder to start completely; this
> wouldn't require a KIP and it would not require clients use different
> technique for newer and older Connect runtimes. (Whether or not we back port
> this is another question altogether, since it's debatable whether the
> behavior of the existing REST resources is truly a bug.)
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