Hi Chris,
Thanks again for the feedback! I've updated the KIP based on our last
discussions. I've decided to include the new endpoint for worker
plugins.
1. Yes I agree, it's best to gate the new behavior.
2. Yes, it was a remnant from the original proposal. I've now removed
the location field.
Thanks,
Mickael
On Tue, Nov 30, 2021 at 3:22 AM Chris Egerton
<chr...@confluent.io.invalid> wrote:
>
> Hi Mickael,
>
> I think that's a great idea! I especially like how we can establish the
> expectation that any plugin type that appears in the response from the GET
> /connector-plugins endpoint will have a corresponding GET
> /connector-plugins/<type>/config endpoint, but (if we decide to add them in
> the future), worker plugins won't be expected to expose this kind of
> information and the different root path helps give a decent hint about this.
>
> I also like the choice to return an empty ConfigDef from Converter::config
> instead of null.
>
> Two things come to mind:
>
> 1. We may want to gate this behind a URL query parameter (maybe something
> like "connectorsOnly") that defaults to the old behavior in order to avoid
> breaking existing tools such as programmatic UIs that use the endpoint
> today to discover the connectors that can be created by the user. We can
> even plan to change the default for that parameter to the newly-proposed
> behavior in the next major release, which should give people enough time to
> either adapt to the expanded response format or add the query parameter to
> their tooling.
>
> 2. The existing GET /connector-plugins endpoint doesn't contain information
> on the location of the plugin on the worker's file system. Do you think we
> should still include this info in the new response format? Correct me if
> I'm wrong but it seems it may have been proposed originally to help prevent
> already-addressed bugs in Connect classloading from striking; all else
> equal, I'd personally err on the side of leaving this info out or at least
> reducing permitted values for it to just "classpath" or "plugin path" in
> order to avoid leaking worker file paths into the REST API, which might
> bother super security-conscious users.
>
> Cheers,
>
> Chris
>
> On Mon, Nov 29, 2021 at 5:52 AM Mickael Maison <mickael.mai...@gmail.com>
> wrote:
>
> > Hi Chris,
> >
> > Yes to keep compatibility we want a default implementation for
> > Converter.configs(), I've updated the KIP.
> >
> > Regarding worker plugins, the use case you described seems valuable.
> > I'd prefer not mixing worker and connector plugins on the same
> > endpoint but I agree using /plugins and /worker-plugins could be
> > confusing.
> >
> > One alternative is to expose all connector-level plugins via the
> > existing /connector-plugins endpoint. In that case, we'd need to keep
> > the current JSON schema and not group plugins by type. As the current
> > schema already has a type field for each entry, we'll still be able to
> > tell them apart. Then we can have /worker-plugins and a relatively
> > clean API. What do you think?
> >
> > Thanks,
> > Mickael
> >
> > On Sun, Nov 28, 2021 at 8:21 PM Chris Egerton
> > <chr...@confluent.io.invalid> wrote:
> > >
> > > 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
> > > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > >
> > > >
> >
