Hi Mickael,
I think one potential use case for exposing worker-level plugins is that it
may make it easier to determine whether a worker is set up correctly (the
current alternative requires looking through log files and can be a little
tedious), and might even make it possible to automatically identify
discrepancies within a cluster by diffing the contents of that endpoint
across each worker. But I don't think this has to be addressed by the
current KIP; the only thing that bothers me a little is that "plugins" is
generic and it may confuse people down the road if we add an endpoint for
worker-level plugins ("why is one just called 'plugins' and the other one
is 'worker-plugins'?"). Probably not worth blocking on, though.
Agreed that the suggestion for improved validation should be made on the
KIP-802 thread.
I also noticed that the newly-proposed config method for the Converter
interface doesn't have a default implementation, making it
backwards-incompatible. Should we add a default implementation that returns
either null or an empty ConfigDef?
Cheers,
Chris
On Fri, Nov 26, 2021 at 8:35 AM Mickael Maison <mickael.mai...@gmail.com>
wrote:
> Hi Chris,
>
> 1. If we want to expose worker plugins, I think we should do it via a
> separate endpoint. But to be honest, I'm not even sure I see strong
> use cases for exposing them as they are either enabled or not and
> can't be changed at runtime. So I'd prefer to stick to "connector
> level" plugins in this KIP. Let me now if you have use cases, I'm open
> to reconsider this choice.
> I'll add that in the rejected alternatives section for now
>
> 2. I remembered seeing issues in the past with multiple plugin.path
> entries but I tried today and I was able to mix and match plugins from
> different paths. So my bad for getting confused.
> Then I agree, it makes more sense to group them by plugin type.
>
> 3. Yes this should be covered in KIP-802:
>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-802%3A+Validation+Support+for+Kafka+Connect+SMT+Options
>
> 4. No particular reason. We can support both formats like today. I've
> updated the KIP
>
> Thanks,
> Mickael
>
>
>
> On Tue, Nov 23, 2021 at 6:40 PM Chris Egerton
> <chr...@confluent.io.invalid> wrote:
> >
> > Hi Mickael,
> >
> > I think the increase in scope here is great and the added value certainly
> > justifies the proposed changes. I have some thoughts but overall I like
> the
> > direction this is going in now.
> >
> > 1. The new /plugins endpoint is described as containing "all plugins that
> > are Connectors, Transformations, Converters, HeaderConverters and
> > Predicates". So essentially, it looks like we want to expose all plugins
> > that are configured on a per-connector basis, but exclude plugins that
> are
> > configured on a per-worker basis (such as config providers and REST
> > extensions). Do you think it may be valuable to expose information on
> > worker-level plugins as well?
> >
> > 2. The description for the new /plugins endpoint also states that
> "Plugins
> > will be grouped by plugin.path. This will make it clear to users what's
> > available to use as it's not possible to use a Connector from one path
> with
> > Transformations from another.". Is this true? I thought that Connect's
> > classloading made it possible to package
> > converters/transformations/predicates completely independently from each
> > other, and to reference them from also-independently-packaged connectors.
> > If it turns out that this is the case, could we consider restructuring
> the
> > response to be grouped by plugin type instead of by classloader? There's
> > also the ungrouped format proposed in KIP-494 (
> >
> https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=120740150
> )
> > which we might consider as well.
> >
> > 3. I think this can be left for a follow-up KIP if necessary, but I'm
> > curious about your thoughts on adding new validate methods to all
> > connector-level plugins that can be used similarly to how the existing
> > Connector::validate method (
> >
> https://github.com/apache/kafka/blob/1e0916580f16b99b911b0ed36e9740dcaeef520e/connect/api/src/main/java/org/apache/kafka/connect/connector/Connector.java#L131-L146
> )
> > is used. This would allow for plugins to perform validation that's more
> > sophisticated than what the ConfigDef is capable of, such as validating
> > combinations of properties like a hostname and credentials for reaching
> it.
> > I know that at least Confluent's Avro, protobuf, and JSON schema
> converters
> > would benefit from this kind of feature. It's a little tangential to this
> > KIP (which at the moment is about discovering plugins and their
> > configuration surfaces, as opposed to validating them), but I figured I'd
> > ask since we're going to be expanding the Converter interface and it may
> be
> > useful to tackle this while we're in the neighborhood.
> >
> > 4. The description for the new /plugins/<type>/<name>/configdef endpoint
> > states that "Name must be the fully qualified class name of the plugin".
> > Any reason not to also support aliases (e.g., "FileStreamSinkConnector"
> or
> > "FileStreamSink" instead of
> > "org.apache.kafka.connect.file.FileStreamSinkConnector")?
> >
> > Cheers,
> >
> > Chris
> >
> > On Tue, Nov 23, 2021 at 12:07 PM Mickael Maison <
> mickael.mai...@gmail.com>
> > wrote:
> >
> > > Thanks all for the feedback!
> > >
> > > Chris,
> > > I agree that fixing the current endpoint helps a lot. Thanks for
> > > raising these JIRAs and submitting a PR!
> > > However thinking about the issue further, I decided to expand the
> > > scope of the KIP to cover all user-visible plugins.
> > > In practice, users want to know about all available plugins not only
> > > connectors. This includes transformations, converters,
> > > header_converters and predicates. As we also want to retrieve
> > > configdef for these too, I think it makes sense to introduce a new
> > > endpoint to do so. Alongside we obviously need a new endpoint for
> > > listing all plugins.
> > >
> > > Gunnar,
> > > I took a look at exposing valid values via the API. I think the issue
> > > is that Validators don't expose a way to retrieve valid values.
> > > Changing validators will have an impact on all components so I'd
> > > prefer to address this requirement in a separate KIP. I agree this
> > > would be an interesting improvement and I'd happy to write a KIP for
> > > it too.
> > >
> > >
> > > I have updated the KIP accordingly. Let me know if you have further
> > > feedback.
> > >
> > > Thanks,
> > > Mickael
> > >
> > > On Tue, Nov 16, 2021 at 9:31 PM Gunnar Morling
> > > <gunnar.morl...@googlemail.com.invalid> wrote:
> > > >
> > > > Hi,
> > > >
> > > > I'm +1 for adding a GET endpoint for obtaining config definitions. It
> > > > always felt odd to me that one has to issue a PUT for that purpose.
> If
> > > > nothing else, it'd be better in terms of discoverability of the KC
> REST
> > > API.
> > > >
> > > > One additional feature request I'd have is to expose the valid enum
> > > > constants for enum-typed options. That'll help to display the values
> in a
> > > > drop-down or via radio buttons in a UI, give us tab completion in
> kcctl,
> > > > etc.
> > > >
> > > > Best,
> > > >
> > > > --Gunnar
> > > >
> > > >
> > > > Am Di., 16. Nov. 2021 um 16:31 Uhr schrieb Chris Egerton
> > > > <chr...@confluent.io.invalid>:
> > > >
> > > > > Hi Viktor,
> > > > >
> > > > > It sounds like there are three major points here in favor of a new
> GET
> > > > > endpoint for connector config defs.
> > > > >
> > > > > 1. You cannot issue a blank ("dummy") request for sink connectors
> > > because a
> > > > > topic list/topic regex has to be supplied (otherwise the PUT
> endpoint
> > > > > returns a 500 response)
> > > > > 2. A dummy request still triggers custom validations by the
> connector,
> > > > > which may be best to avoid if we know for sure that the config
> isn't
> > > worth
> > > > > validating yet
> > > > > 3. It's more ergonomic and intuitive to be able to issue a GET
> request
> > > > > without having to give a dummy connector config
> > > > >
> > > > > With regards to 1, this is actually a bug in Connect (
> > > > > https://issues.apache.org/jira/browse/KAFKA-13327) with a fix
> already
> > > > > implemented and awaiting committer review (
> > > > > https://github.com/apache/kafka/pull/11369). I think it'd be
> better to
> > > > > focus on fixing this bug in general instead of implementing a new
> REST
> > > > > endpoint in order to allow people to work around it.
> > > > >
> > > > > With regards to 2, this is technically possible but I'm unsure
> it'd be
> > > too
> > > > > common out in the wild given that most validations that could be
> > > expensive
> > > > > would involve things like connecting to a database, checking if a
> cloud
> > > > > storage bucket exists, etc., none of which are possible without
> some
> > > > > configuration properties from the user (db hostname, bucket name,
> > > etc.).
> > > > >
> > > > > With regards to 3, I do agree that it'd be easier for people
> designing
> > > UIs
> > > > > to have a GET API to work against. I'm just not sure it's worth the
> > > > > additional implementation, testing, and maintenance burden. If it
> were
> > > > > possible to issue a PUT request without unexpected 500s for invalid
> > > > > configs, would that suffice? AFAICT it'd basically be as simple as
> > > issuing
> > > > > a PUT request with a dummy body consisting of nothing except the
> > > connector
> > > > > class (which at this point we might even make unnecessary and just
> > > > > automatically replace with the connector class from the URL) and
> then
> > > > > filtering the response to just grab the "definition" field of each
> > > element
> > > > > in the "configs" array in the response.
> > > > >
> > > > > Cheers,
> > > > >
> > > > > Chris
> > > > >
> > > > > On Tue, Nov 16, 2021 at 9:52 AM Viktor Somogyi-Vass <
> > > > > viktorsomo...@gmail.com>
> > > > > wrote:
> > > > >
> > > > > > Hi Folks,
> > > > > >
> > > > > > I too think this would be a very useful feature. Some of our
> > > management
> > > > > > applications would provide a wizard for creating connectors. In
> this
> > > > > > scenario the user basically would fill out a sample configuration
> > > > > generated
> > > > > > by the UI which would send it back to Connect for validation and
> > > > > eventually
> > > > > > create a new connector. The first part of this workflow can be
> > > enhanced
> > > > > if
> > > > > > we had an API that can return the configuration definition of the
> > > given
> > > > > > type of connector as the UI application would be able to
> generate a
> > > > > sample
> > > > > > for the user based on that (nicely drawn diagram:
> > > > > > https://imgur.com/a/7S1Xwm5).
> > > > > > The connector-plugins/{connectorType}/config/validate API
> essentially
> > > > > works
> > > > > > and returns the data that we need, however it is a HTTP PUT API
> that
> > > is a
> > > > > > bit unintuitive for a fetch-like functionality and also
> functionally
> > > > > > different as it validates the given (dummy) request. In case of
> sink
> > > > > > connectors one would need to also provide a topic name.
> > > > > >
> > > > > > A suggestion for the KIP: I think it can be useful to return the
> > > config
> > > > > > groups and the connector class' name similarly to the validate
> API
> > > just
> > > > > in
> > > > > > case any frontend needs them (and also the response would be more
> > > like
> > > > > the
> > > > > > validate API but simpler).
> > > > > >
> > > > > > Viktor
> > > > > >
> > > > > > On Fri, Aug 20, 2021 at 4:51 PM Ryanne Dolan <
> ryannedo...@gmail.com>
> > > > > > wrote:
> > > > > >
> > > > > > > I think it'd be worth adding a GET version, fwiw. Could be the
> same
> > > > > > handler
> > > > > > > with just a different spelling maybe.
> > > > > > >
> > > > > > > On Fri, Aug 20, 2021, 7:44 AM Mickael Maison <
> > > mickael.mai...@gmail.com
> > > > > >
> > > > > > > wrote:
> > > > > > >
> > > > > > > > Hi Chris,
> > > > > > > >
> > > > > > > > You're right, you can achieve the same functionality using
> the
> > > > > > > > existing validate endpoint.
> > > > > > > > In my mind it was only for validation once you have build a
> > > > > > > > configuration but when used with an empty configuration, it
> > > basically
> > > > > > > > serves the same purpose as the proposed new endpoint.
> > > > > > > >
> > > > > > > > I think it's a bit easier to use a GET endpoint but I don't
> > > think it
> > > > > > > > really warrants a different endpoint.
> > > > > > > >
> > > > > > > > Thanks
> > > > > > > >
> > > > > > > > On Thu, Aug 19, 2021 at 2:56 PM Chris Egerton
> > > > > > > > <chr...@confluent.io.invalid> wrote:
> > > > > > > > >
> > > > > > > > > Hi Mickael,
> > > > > > > > >
> > > > > > > > > I'm wondering about the use case here. The motivation
> section
> > > > > states
> > > > > > > that
> > > > > > > > > "Connect does not provide a way to see what configurations
> a
> > > > > > connector
> > > > > > > > > requires. Instead users have to go look at the connector
> > > > > > documentation
> > > > > > > or
> > > > > > > > > in the worst case, look directly at the connector source
> > > code.",
> > > > > and
> > > > > > > that
> > > > > > > > > with this KIP, "users will be able to discover the required
> > > > > > > > configurations
> > > > > > > > > for connectors installed in a Connect cluster" and "tools
> will
> > > be
> > > > > > able
> > > > > > > to
> > > > > > > > > generate wizards for configuring and starting connectors".
> > > > > > > > >
> > > > > > > > > Does the existing "PUT
> > > > > > > > /connector-plugins/{connector-type}/config/validate"
> > > > > > > > > endpoint not address these points? What will the
> newly-proposed
> > > > > > > endpoint
> > > > > > > > > allow users to do that they will not already be able to do
> > > with the
> > > > > > > > > existing endpoint?
> > > > > > > > >
> > > > > > > > > Cheers,
> > > > > > > > >
> > > > > > > > > Chris
> > > > > > > > >
> > > > > > > > > On Thu, Aug 19, 2021 at 9:20 AM Mickael Maison <
> > > > > > > mickael.mai...@gmail.com
> > > > > > > > >
> > > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > > Hi,
> > > > > > > > > >
> > > > > > > > > > I've created KIP-769 to expose connector configuration
> > > > > definitions
> > > > > > in
> > > > > > > > > > the Connect API
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-769%3A+Connect+API+to+retrieve+connector+configuration+definitions
> > > > > > > > > >
> > > > > > > > > > Please take a look and let me know if you have any
> feedback.
> > > > > > > > > >
> > > > > > > > > > Thanks
> > > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > >
>
