Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi all,

I wanted to let you know that I have made the following small change to the
`kafka-features` CLI tool description in the KIP-584 write up. The purpose
is to ensure the design is compatible with post KIP-500 world. I have
eliminated the facility in Admin#describeFeatures API to be able to
optionally send a describeFeatures request to the controller. This facility
was originally seen useful for (1) debugability and (2) slightly better
consistency guarantees in the CLI tool that reads features before updating
them. But in hindsight it now poses a hindrance to post KIP-500 world where
no client would be able to access the controller directly. So, when looking
at cost vs benefit, this facility does not feel useful enough and therefore
I've removed it. We can discuss if it becomes necessary in the future, and
implement a suitable solution.

The corresponding PR containing this change is
https://github.com/apache/kafka/pull/9536 .

Please let me know if you have any questions or concerns.


Cheers,
Kowshik


On Thu, Oct 15, 2020 at 10:17 AM Jun Rao  wrote:

> Hi, Kowshik,
>
> Thanks for the update. Those changes look good to me.
>
> Jun
>
> On Tue, Oct 13, 2020 at 4:50 PM Kowshik Prakasam 
> wrote:
>
> > Hi all,
> >
> > I wanted to let you know that I have made the following minor changes to
> > the `kafka-features` CLI tool description in the KIP-584 write up. The
> > purpose is to ensure the design is correct for a few things which came up
> > during implementation:
> >
> > 1. The CLI tool now produces a tab-formatted output instead of JSON. This
> > aligns with the type of format produced by other admin CLI tools of
> Kafka,
> > ex: `kafka-topics`.
> > 2. Whenever feature updates are performed, the output of the CLI tool
> shows
> > the result of each feature update that was applied.
> > 3. The CLI tool accepts an optional argument `--dry-run` which lets the
> > user preview the feature updates before applying them.
> >
> > The following section of the KIP has been updated with the above changes:
> >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Toolingsupport
> >
> > Please let me know if you have any questions.
> >
> >
> > Cheers,
> > Kowshik
> >
> >
> > On Thu, Oct 8, 2020 at 1:12 AM Kowshik Prakasam 
> > wrote:
> >
> > > Hi Jun,
> > >
> > > This is a very good point. I have updated the feature version
> deprecation
> > > section mentioning the same:
> > >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
> > > .
> > >
> > > Thank you for the suggestion.
> > >
> > >
> > > Cheers,
> > > Kowshik
> > >
> > >
> > > On Tue, Oct 6, 2020 at 5:30 PM Jun Rao  wrote:
> > >
> > >> Hi, Kowshik,
> > >>
> > >> Thanks for the follow up. Both look good to me.
> > >>
> > >> For 2, it would be useful to also add that an admin should make sure
> > that
> > >> no clients are using a deprecated feature version (e.g. using the
> client
> > >> version metric) before deploying a release that deprecates it.
> > >>
> > >> Thanks,
> > >>
> > >> Jun
> > >>
> > >> On Tue, Oct 6, 2020 at 3:46 PM Kowshik Prakasam <
> kpraka...@confluent.io
> > >
> > >> wrote:
> > >>
> > >> > Hi Jun,
> > >> >
> > >> > I have added the following details in the KIP-584 write up:
> > >> >
> > >> > 1. Deployment, IBP deprecation and avoidance of double rolls. This
> > >> section
> > >> > talks about the various phases of work that would be required to use
> > >> this
> > >> > KIP to eventually avoid Broker double rolls in the cluster (whenever
> > IBP
> > >> > values are advanced). Link to section:
> > >> >
> > >> >
> > >>
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Deployment,IBPdeprecationandavoidanceofdoublerolls
> > >> > .
> > >> >
> > >> > 2. Feature version deprecation. This section explains the idea for
> > >> feature
> > >> > version deprecation (using highest supported feature min version)
> > which
> > >> you
> > >> > had proposed during code review:
> > >> >
> > >> >
> > >>
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
> > >> > .
> > >> >
> > >> > Please let me know if you have any questions.
> > >> >
> > >> >
> > >> > Cheers,
> > >> > Kowshik
> > >> >
> > >> >
> > >> > On Tue, Sep 29, 2020 at 11:07 AM Jun Rao  wrote:
> > >> >
> > >> > > Hi, Kowshik,
> > >> > >
> > >> > > Thanks for the update. Regarding enabling a single rolling restart
> > in
> > >> the
> > >> > > future, could we sketch out a bit how this will work by treating
> IBP
> > >> as a
> > >> > > feature? For example, IBP currently uses the release version and
> > this
> > >> KIP
> > >> > > uses an integer for versions. How do we bridge the gap between the
> > >> two?
> > >> > > Does 

Re: [VOTE] KIP-584: Versioning scheme for features

[Jun Rao]

Hi, Kowshik,

Thanks for the update. Those changes look good to me.

Jun

On Tue, Oct 13, 2020 at 4:50 PM Kowshik Prakasam 
wrote:

> Hi all,
>
> I wanted to let you know that I have made the following minor changes to
> the `kafka-features` CLI tool description in the KIP-584 write up. The
> purpose is to ensure the design is correct for a few things which came up
> during implementation:
>
> 1. The CLI tool now produces a tab-formatted output instead of JSON. This
> aligns with the type of format produced by other admin CLI tools of Kafka,
> ex: `kafka-topics`.
> 2. Whenever feature updates are performed, the output of the CLI tool shows
> the result of each feature update that was applied.
> 3. The CLI tool accepts an optional argument `--dry-run` which lets the
> user preview the feature updates before applying them.
>
> The following section of the KIP has been updated with the above changes:
>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Toolingsupport
>
> Please let me know if you have any questions.
>
>
> Cheers,
> Kowshik
>
>
> On Thu, Oct 8, 2020 at 1:12 AM Kowshik Prakasam 
> wrote:
>
> > Hi Jun,
> >
> > This is a very good point. I have updated the feature version deprecation
> > section mentioning the same:
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
> > .
> >
> > Thank you for the suggestion.
> >
> >
> > Cheers,
> > Kowshik
> >
> >
> > On Tue, Oct 6, 2020 at 5:30 PM Jun Rao  wrote:
> >
> >> Hi, Kowshik,
> >>
> >> Thanks for the follow up. Both look good to me.
> >>
> >> For 2, it would be useful to also add that an admin should make sure
> that
> >> no clients are using a deprecated feature version (e.g. using the client
> >> version metric) before deploying a release that deprecates it.
> >>
> >> Thanks,
> >>
> >> Jun
> >>
> >> On Tue, Oct 6, 2020 at 3:46 PM Kowshik Prakasam  >
> >> wrote:
> >>
> >> > Hi Jun,
> >> >
> >> > I have added the following details in the KIP-584 write up:
> >> >
> >> > 1. Deployment, IBP deprecation and avoidance of double rolls. This
> >> section
> >> > talks about the various phases of work that would be required to use
> >> this
> >> > KIP to eventually avoid Broker double rolls in the cluster (whenever
> IBP
> >> > values are advanced). Link to section:
> >> >
> >> >
> >>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Deployment,IBPdeprecationandavoidanceofdoublerolls
> >> > .
> >> >
> >> > 2. Feature version deprecation. This section explains the idea for
> >> feature
> >> > version deprecation (using highest supported feature min version)
> which
> >> you
> >> > had proposed during code review:
> >> >
> >> >
> >>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
> >> > .
> >> >
> >> > Please let me know if you have any questions.
> >> >
> >> >
> >> > Cheers,
> >> > Kowshik
> >> >
> >> >
> >> > On Tue, Sep 29, 2020 at 11:07 AM Jun Rao  wrote:
> >> >
> >> > > Hi, Kowshik,
> >> > >
> >> > > Thanks for the update. Regarding enabling a single rolling restart
> in
> >> the
> >> > > future, could we sketch out a bit how this will work by treating IBP
> >> as a
> >> > > feature? For example, IBP currently uses the release version and
> this
> >> KIP
> >> > > uses an integer for versions. How do we bridge the gap between the
> >> two?
> >> > > Does min.version still make sense for IBP as a feature?
> >> > >
> >> > > Thanks,
> >> > >
> >> > > Jun
> >> > >
> >> > > On Fri, Sep 25, 2020 at 5:57 PM Kowshik Prakasam <
> >> kpraka...@confluent.io
> >> > >
> >> > > wrote:
> >> > >
> >> > > > Hi Colin,
> >> > > >
> >> > > > Thanks for the feedback. Those are very good points. I have made
> the
> >> > > > following changes to the KIP as you had suggested:
> >> > > > 1. Included the `timeoutMs` field in the `UpdateFeaturesRequest`
> >> > schema.
> >> > > > The initial implementation won't be making use of the field, but
> we
> >> can
> >> > > > always use it in the future as the need arises.
> >> > > > 2. Modified the `FinalizedFeaturesEpoch` field in
> >> `ApiVersionsResponse`
> >> > > to
> >> > > > use int64. This is to avoid overflow problems in the future once
> ZK
> >> is
> >> > > > gone.
> >> > > >
> >> > > > I have also incorporated these changes into the versioning write
> >> path
> >> > PR
> >> > > > that is currently under review:
> >> > > https://github.com/apache/kafka/pull/9001.
> >> > > >
> >> > > >
> >> > > > Cheers,
> >> > > > Kowshik
> >> > > >
> >> > > >
> >> > > >
> >> > > > On Fri, Sep 25, 2020 at 4:57 PM Kowshik Prakasam <
> >> > kpraka...@confluent.io
> >> > > >
> >> > > > wrote:
> >> > > >
> >> > > > > Hi Jun,
> >> > > > >
> >> > > > > Thanks for the feedback. It's a very 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi all,

I wanted to let you know that I have made the following minor changes to
the `kafka-features` CLI tool description in the KIP-584 write up. The
purpose is to ensure the design is correct for a few things which came up
during implementation:

1. The CLI tool now produces a tab-formatted output instead of JSON. This
aligns with the type of format produced by other admin CLI tools of Kafka,
ex: `kafka-topics`.
2. Whenever feature updates are performed, the output of the CLI tool shows
the result of each feature update that was applied.
3. The CLI tool accepts an optional argument `--dry-run` which lets the
user preview the feature updates before applying them.

The following section of the KIP has been updated with the above changes:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Toolingsupport

Please let me know if you have any questions.


Cheers,
Kowshik


On Thu, Oct 8, 2020 at 1:12 AM Kowshik Prakasam 
wrote:

> Hi Jun,
>
> This is a very good point. I have updated the feature version deprecation
> section mentioning the same:
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
> .
>
> Thank you for the suggestion.
>
>
> Cheers,
> Kowshik
>
>
> On Tue, Oct 6, 2020 at 5:30 PM Jun Rao  wrote:
>
>> Hi, Kowshik,
>>
>> Thanks for the follow up. Both look good to me.
>>
>> For 2, it would be useful to also add that an admin should make sure that
>> no clients are using a deprecated feature version (e.g. using the client
>> version metric) before deploying a release that deprecates it.
>>
>> Thanks,
>>
>> Jun
>>
>> On Tue, Oct 6, 2020 at 3:46 PM Kowshik Prakasam 
>> wrote:
>>
>> > Hi Jun,
>> >
>> > I have added the following details in the KIP-584 write up:
>> >
>> > 1. Deployment, IBP deprecation and avoidance of double rolls. This
>> section
>> > talks about the various phases of work that would be required to use
>> this
>> > KIP to eventually avoid Broker double rolls in the cluster (whenever IBP
>> > values are advanced). Link to section:
>> >
>> >
>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Deployment,IBPdeprecationandavoidanceofdoublerolls
>> > .
>> >
>> > 2. Feature version deprecation. This section explains the idea for
>> feature
>> > version deprecation (using highest supported feature min version) which
>> you
>> > had proposed during code review:
>> >
>> >
>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
>> > .
>> >
>> > Please let me know if you have any questions.
>> >
>> >
>> > Cheers,
>> > Kowshik
>> >
>> >
>> > On Tue, Sep 29, 2020 at 11:07 AM Jun Rao  wrote:
>> >
>> > > Hi, Kowshik,
>> > >
>> > > Thanks for the update. Regarding enabling a single rolling restart in
>> the
>> > > future, could we sketch out a bit how this will work by treating IBP
>> as a
>> > > feature? For example, IBP currently uses the release version and this
>> KIP
>> > > uses an integer for versions. How do we bridge the gap between the
>> two?
>> > > Does min.version still make sense for IBP as a feature?
>> > >
>> > > Thanks,
>> > >
>> > > Jun
>> > >
>> > > On Fri, Sep 25, 2020 at 5:57 PM Kowshik Prakasam <
>> kpraka...@confluent.io
>> > >
>> > > wrote:
>> > >
>> > > > Hi Colin,
>> > > >
>> > > > Thanks for the feedback. Those are very good points. I have made the
>> > > > following changes to the KIP as you had suggested:
>> > > > 1. Included the `timeoutMs` field in the `UpdateFeaturesRequest`
>> > schema.
>> > > > The initial implementation won't be making use of the field, but we
>> can
>> > > > always use it in the future as the need arises.
>> > > > 2. Modified the `FinalizedFeaturesEpoch` field in
>> `ApiVersionsResponse`
>> > > to
>> > > > use int64. This is to avoid overflow problems in the future once ZK
>> is
>> > > > gone.
>> > > >
>> > > > I have also incorporated these changes into the versioning write
>> path
>> > PR
>> > > > that is currently under review:
>> > > https://github.com/apache/kafka/pull/9001.
>> > > >
>> > > >
>> > > > Cheers,
>> > > > Kowshik
>> > > >
>> > > >
>> > > >
>> > > > On Fri, Sep 25, 2020 at 4:57 PM Kowshik Prakasam <
>> > kpraka...@confluent.io
>> > > >
>> > > > wrote:
>> > > >
>> > > > > Hi Jun,
>> > > > >
>> > > > > Thanks for the feedback. It's a very good point. I have now
>> modified
>> > > the
>> > > > > KIP-584 write-up "goals" section a bit. It now mentions one of the
>> > > goals
>> > > > as
>> > > > > enabling rolling upgrades using a single restart (instead of 2).
>> > Also I
>> > > > > have removed the text explicitly aiming for deprecation of IBP.
>> Note
>> > > that
>> > > > > previously under "Potential features in Kafka" the IBP was
>> mentioned
>> > > > under
>> > > > > point (4) 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi Jun,

This is a very good point. I have updated the feature version deprecation
section mentioning the same:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
.

Thank you for the suggestion.


Cheers,
Kowshik


On Tue, Oct 6, 2020 at 5:30 PM Jun Rao  wrote:

> Hi, Kowshik,
>
> Thanks for the follow up. Both look good to me.
>
> For 2, it would be useful to also add that an admin should make sure that
> no clients are using a deprecated feature version (e.g. using the client
> version metric) before deploying a release that deprecates it.
>
> Thanks,
>
> Jun
>
> On Tue, Oct 6, 2020 at 3:46 PM Kowshik Prakasam 
> wrote:
>
> > Hi Jun,
> >
> > I have added the following details in the KIP-584 write up:
> >
> > 1. Deployment, IBP deprecation and avoidance of double rolls. This
> section
> > talks about the various phases of work that would be required to use this
> > KIP to eventually avoid Broker double rolls in the cluster (whenever IBP
> > values are advanced). Link to section:
> >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Deployment,IBPdeprecationandavoidanceofdoublerolls
> > .
> >
> > 2. Feature version deprecation. This section explains the idea for
> feature
> > version deprecation (using highest supported feature min version) which
> you
> > had proposed during code review:
> >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
> > .
> >
> > Please let me know if you have any questions.
> >
> >
> > Cheers,
> > Kowshik
> >
> >
> > On Tue, Sep 29, 2020 at 11:07 AM Jun Rao  wrote:
> >
> > > Hi, Kowshik,
> > >
> > > Thanks for the update. Regarding enabling a single rolling restart in
> the
> > > future, could we sketch out a bit how this will work by treating IBP
> as a
> > > feature? For example, IBP currently uses the release version and this
> KIP
> > > uses an integer for versions. How do we bridge the gap between the two?
> > > Does min.version still make sense for IBP as a feature?
> > >
> > > Thanks,
> > >
> > > Jun
> > >
> > > On Fri, Sep 25, 2020 at 5:57 PM Kowshik Prakasam <
> kpraka...@confluent.io
> > >
> > > wrote:
> > >
> > > > Hi Colin,
> > > >
> > > > Thanks for the feedback. Those are very good points. I have made the
> > > > following changes to the KIP as you had suggested:
> > > > 1. Included the `timeoutMs` field in the `UpdateFeaturesRequest`
> > schema.
> > > > The initial implementation won't be making use of the field, but we
> can
> > > > always use it in the future as the need arises.
> > > > 2. Modified the `FinalizedFeaturesEpoch` field in
> `ApiVersionsResponse`
> > > to
> > > > use int64. This is to avoid overflow problems in the future once ZK
> is
> > > > gone.
> > > >
> > > > I have also incorporated these changes into the versioning write path
> > PR
> > > > that is currently under review:
> > > https://github.com/apache/kafka/pull/9001.
> > > >
> > > >
> > > > Cheers,
> > > > Kowshik
> > > >
> > > >
> > > >
> > > > On Fri, Sep 25, 2020 at 4:57 PM Kowshik Prakasam <
> > kpraka...@confluent.io
> > > >
> > > > wrote:
> > > >
> > > > > Hi Jun,
> > > > >
> > > > > Thanks for the feedback. It's a very good point. I have now
> modified
> > > the
> > > > > KIP-584 write-up "goals" section a bit. It now mentions one of the
> > > goals
> > > > as
> > > > > enabling rolling upgrades using a single restart (instead of 2).
> > Also I
> > > > > have removed the text explicitly aiming for deprecation of IBP.
> Note
> > > that
> > > > > previously under "Potential features in Kafka" the IBP was
> mentioned
> > > > under
> > > > > point (4) as a possible coarse-grained feature. Hopefully, now the
> 2
> > > > > sections of the KIP align with each other well.
> > > > >
> > > > >
> > > > > Cheers,
> > > > > Kowshik
> > > > >
> > > > >
> > > > > On Fri, Sep 25, 2020 at 2:03 PM Colin McCabe 
> > > wrote:
> > > > >
> > > > >> On Tue, Sep 22, 2020, at 00:43, Kowshik Prakasam wrote:
> > > > >> > Hi all,
> > > > >> >
> > > > >> > I wanted to let you know that I have made the following changes
> to
> > > the
> > > > >> > KIP-584 write up. The purpose is to ensure the design is correct
> > > for a
> > > > >> few
> > > > >> > things which came up during implementation:
> > > > >> >
> > > > >>
> > > > >> Hi Kowshik,
> > > > >>
> > > > >> Thanks for the updates.
> > > > >>
> > > > >> >
> > > > >> > 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller
> > API
> > > is
> > > > >> no
> > > > >> > longer transactional. Going forward, we allow for individual
> > > > >> FeatureUpdate
> > > > >> > to succeed/fail in the request. As a result, the response schema
> > now
> > > > >> > contains an error code per FeatureUpdate as well as a top-level
> > > error
> > > > >> code.
> > > > >> > Overall 

Re: [VOTE] KIP-584: Versioning scheme for features

[Jun Rao]

Hi, Kowshik,

Thanks for the follow up. Both look good to me.

For 2, it would be useful to also add that an admin should make sure that
no clients are using a deprecated feature version (e.g. using the client
version metric) before deploying a release that deprecates it.

Thanks,

Jun

On Tue, Oct 6, 2020 at 3:46 PM Kowshik Prakasam 
wrote:

> Hi Jun,
>
> I have added the following details in the KIP-584 write up:
>
> 1. Deployment, IBP deprecation and avoidance of double rolls. This section
> talks about the various phases of work that would be required to use this
> KIP to eventually avoid Broker double rolls in the cluster (whenever IBP
> values are advanced). Link to section:
>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Deployment,IBPdeprecationandavoidanceofdoublerolls
> .
>
> 2. Feature version deprecation. This section explains the idea for feature
> version deprecation (using highest supported feature min version) which you
> had proposed during code review:
>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
> .
>
> Please let me know if you have any questions.
>
>
> Cheers,
> Kowshik
>
>
> On Tue, Sep 29, 2020 at 11:07 AM Jun Rao  wrote:
>
> > Hi, Kowshik,
> >
> > Thanks for the update. Regarding enabling a single rolling restart in the
> > future, could we sketch out a bit how this will work by treating IBP as a
> > feature? For example, IBP currently uses the release version and this KIP
> > uses an integer for versions. How do we bridge the gap between the two?
> > Does min.version still make sense for IBP as a feature?
> >
> > Thanks,
> >
> > Jun
> >
> > On Fri, Sep 25, 2020 at 5:57 PM Kowshik Prakasam  >
> > wrote:
> >
> > > Hi Colin,
> > >
> > > Thanks for the feedback. Those are very good points. I have made the
> > > following changes to the KIP as you had suggested:
> > > 1. Included the `timeoutMs` field in the `UpdateFeaturesRequest`
> schema.
> > > The initial implementation won't be making use of the field, but we can
> > > always use it in the future as the need arises.
> > > 2. Modified the `FinalizedFeaturesEpoch` field in `ApiVersionsResponse`
> > to
> > > use int64. This is to avoid overflow problems in the future once ZK is
> > > gone.
> > >
> > > I have also incorporated these changes into the versioning write path
> PR
> > > that is currently under review:
> > https://github.com/apache/kafka/pull/9001.
> > >
> > >
> > > Cheers,
> > > Kowshik
> > >
> > >
> > >
> > > On Fri, Sep 25, 2020 at 4:57 PM Kowshik Prakasam <
> kpraka...@confluent.io
> > >
> > > wrote:
> > >
> > > > Hi Jun,
> > > >
> > > > Thanks for the feedback. It's a very good point. I have now modified
> > the
> > > > KIP-584 write-up "goals" section a bit. It now mentions one of the
> > goals
> > > as
> > > > enabling rolling upgrades using a single restart (instead of 2).
> Also I
> > > > have removed the text explicitly aiming for deprecation of IBP. Note
> > that
> > > > previously under "Potential features in Kafka" the IBP was mentioned
> > > under
> > > > point (4) as a possible coarse-grained feature. Hopefully, now the 2
> > > > sections of the KIP align with each other well.
> > > >
> > > >
> > > > Cheers,
> > > > Kowshik
> > > >
> > > >
> > > > On Fri, Sep 25, 2020 at 2:03 PM Colin McCabe 
> > wrote:
> > > >
> > > >> On Tue, Sep 22, 2020, at 00:43, Kowshik Prakasam wrote:
> > > >> > Hi all,
> > > >> >
> > > >> > I wanted to let you know that I have made the following changes to
> > the
> > > >> > KIP-584 write up. The purpose is to ensure the design is correct
> > for a
> > > >> few
> > > >> > things which came up during implementation:
> > > >> >
> > > >>
> > > >> Hi Kowshik,
> > > >>
> > > >> Thanks for the updates.
> > > >>
> > > >> >
> > > >> > 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller
> API
> > is
> > > >> no
> > > >> > longer transactional. Going forward, we allow for individual
> > > >> FeatureUpdate
> > > >> > to succeed/fail in the request. As a result, the response schema
> now
> > > >> > contains an error code per FeatureUpdate as well as a top-level
> > error
> > > >> code.
> > > >> > Overall this is a better design because it better represents the
> > > nature
> > > >> of
> > > >> > the API: each FeatureUpdate in the request is independent of the
> > other
> > > >> > updates, and the controller can process/apply these independently
> to
> > > ZK.
> > > >> > When an UPDATE_FEATURES request fails, this new design provides
> > better
> > > >> > clarity to the caller on which FeatureUpdate could not be applied
> > (via
> > > >> the
> > > >> > individual error codes). In the previous design, we were unable to
> > > >> achieve
> > > >> > such an increased level of clarity in communicating the error
> codes.
> > > >> >
> > > >>
> > > >> OK
> > > >>
> > > >> >
> > > >> > 2. Due to #1, 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi Jun,

I have added the following details in the KIP-584 write up:

1. Deployment, IBP deprecation and avoidance of double rolls. This section
talks about the various phases of work that would be required to use this
KIP to eventually avoid Broker double rolls in the cluster (whenever IBP
values are advanced). Link to section:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Deployment,IBPdeprecationandavoidanceofdoublerolls
.

2. Feature version deprecation. This section explains the idea for feature
version deprecation (using highest supported feature min version) which you
had proposed during code review:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-Featureversiondeprecation
.

Please let me know if you have any questions.


Cheers,
Kowshik


On Tue, Sep 29, 2020 at 11:07 AM Jun Rao  wrote:

> Hi, Kowshik,
>
> Thanks for the update. Regarding enabling a single rolling restart in the
> future, could we sketch out a bit how this will work by treating IBP as a
> feature? For example, IBP currently uses the release version and this KIP
> uses an integer for versions. How do we bridge the gap between the two?
> Does min.version still make sense for IBP as a feature?
>
> Thanks,
>
> Jun
>
> On Fri, Sep 25, 2020 at 5:57 PM Kowshik Prakasam 
> wrote:
>
> > Hi Colin,
> >
> > Thanks for the feedback. Those are very good points. I have made the
> > following changes to the KIP as you had suggested:
> > 1. Included the `timeoutMs` field in the `UpdateFeaturesRequest` schema.
> > The initial implementation won't be making use of the field, but we can
> > always use it in the future as the need arises.
> > 2. Modified the `FinalizedFeaturesEpoch` field in `ApiVersionsResponse`
> to
> > use int64. This is to avoid overflow problems in the future once ZK is
> > gone.
> >
> > I have also incorporated these changes into the versioning write path PR
> > that is currently under review:
> https://github.com/apache/kafka/pull/9001.
> >
> >
> > Cheers,
> > Kowshik
> >
> >
> >
> > On Fri, Sep 25, 2020 at 4:57 PM Kowshik Prakasam  >
> > wrote:
> >
> > > Hi Jun,
> > >
> > > Thanks for the feedback. It's a very good point. I have now modified
> the
> > > KIP-584 write-up "goals" section a bit. It now mentions one of the
> goals
> > as
> > > enabling rolling upgrades using a single restart (instead of 2). Also I
> > > have removed the text explicitly aiming for deprecation of IBP. Note
> that
> > > previously under "Potential features in Kafka" the IBP was mentioned
> > under
> > > point (4) as a possible coarse-grained feature. Hopefully, now the 2
> > > sections of the KIP align with each other well.
> > >
> > >
> > > Cheers,
> > > Kowshik
> > >
> > >
> > > On Fri, Sep 25, 2020 at 2:03 PM Colin McCabe 
> wrote:
> > >
> > >> On Tue, Sep 22, 2020, at 00:43, Kowshik Prakasam wrote:
> > >> > Hi all,
> > >> >
> > >> > I wanted to let you know that I have made the following changes to
> the
> > >> > KIP-584 write up. The purpose is to ensure the design is correct
> for a
> > >> few
> > >> > things which came up during implementation:
> > >> >
> > >>
> > >> Hi Kowshik,
> > >>
> > >> Thanks for the updates.
> > >>
> > >> >
> > >> > 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller API
> is
> > >> no
> > >> > longer transactional. Going forward, we allow for individual
> > >> FeatureUpdate
> > >> > to succeed/fail in the request. As a result, the response schema now
> > >> > contains an error code per FeatureUpdate as well as a top-level
> error
> > >> code.
> > >> > Overall this is a better design because it better represents the
> > nature
> > >> of
> > >> > the API: each FeatureUpdate in the request is independent of the
> other
> > >> > updates, and the controller can process/apply these independently to
> > ZK.
> > >> > When an UPDATE_FEATURES request fails, this new design provides
> better
> > >> > clarity to the caller on which FeatureUpdate could not be applied
> (via
> > >> the
> > >> > individual error codes). In the previous design, we were unable to
> > >> achieve
> > >> > such an increased level of clarity in communicating the error codes.
> > >> >
> > >>
> > >> OK
> > >>
> > >> >
> > >> > 2. Due to #1, there were some minor changes required to the proposed
> > >> Admin
> > >> > APIs (describeFeatures and updateFeatures). A few unnecessary public
> > >> APIs
> > >> > have been removed, and couple essential ones have been added. The
> > latest
> > >> > changes now represent the latest design.
> > >> >
> > >> > 3. The timeoutMs field has been removed from the the UPDATE_FEATURES
> > API
> > >> > request, since it was not found to be required during
> implementation.
> > >> >
> > >>
> > >> Please don't get rid of timeoutMs.  timeoutMs is required if you want
> to
> > >> implement the ability to timeout the call if the controller can't get
> > to it
> > 

Re: [VOTE] KIP-584: Versioning scheme for features

[Jun Rao]

Hi, Kowshik,

Thanks for the update. Regarding enabling a single rolling restart in the
future, could we sketch out a bit how this will work by treating IBP as a
feature? For example, IBP currently uses the release version and this KIP
uses an integer for versions. How do we bridge the gap between the two?
Does min.version still make sense for IBP as a feature?

Thanks,

Jun

On Fri, Sep 25, 2020 at 5:57 PM Kowshik Prakasam 
wrote:

> Hi Colin,
>
> Thanks for the feedback. Those are very good points. I have made the
> following changes to the KIP as you had suggested:
> 1. Included the `timeoutMs` field in the `UpdateFeaturesRequest` schema.
> The initial implementation won't be making use of the field, but we can
> always use it in the future as the need arises.
> 2. Modified the `FinalizedFeaturesEpoch` field in `ApiVersionsResponse` to
> use int64. This is to avoid overflow problems in the future once ZK is
> gone.
>
> I have also incorporated these changes into the versioning write path PR
> that is currently under review: https://github.com/apache/kafka/pull/9001.
>
>
> Cheers,
> Kowshik
>
>
>
> On Fri, Sep 25, 2020 at 4:57 PM Kowshik Prakasam 
> wrote:
>
> > Hi Jun,
> >
> > Thanks for the feedback. It's a very good point. I have now modified the
> > KIP-584 write-up "goals" section a bit. It now mentions one of the goals
> as
> > enabling rolling upgrades using a single restart (instead of 2). Also I
> > have removed the text explicitly aiming for deprecation of IBP. Note that
> > previously under "Potential features in Kafka" the IBP was mentioned
> under
> > point (4) as a possible coarse-grained feature. Hopefully, now the 2
> > sections of the KIP align with each other well.
> >
> >
> > Cheers,
> > Kowshik
> >
> >
> > On Fri, Sep 25, 2020 at 2:03 PM Colin McCabe  wrote:
> >
> >> On Tue, Sep 22, 2020, at 00:43, Kowshik Prakasam wrote:
> >> > Hi all,
> >> >
> >> > I wanted to let you know that I have made the following changes to the
> >> > KIP-584 write up. The purpose is to ensure the design is correct for a
> >> few
> >> > things which came up during implementation:
> >> >
> >>
> >> Hi Kowshik,
> >>
> >> Thanks for the updates.
> >>
> >> >
> >> > 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller API is
> >> no
> >> > longer transactional. Going forward, we allow for individual
> >> FeatureUpdate
> >> > to succeed/fail in the request. As a result, the response schema now
> >> > contains an error code per FeatureUpdate as well as a top-level error
> >> code.
> >> > Overall this is a better design because it better represents the
> nature
> >> of
> >> > the API: each FeatureUpdate in the request is independent of the other
> >> > updates, and the controller can process/apply these independently to
> ZK.
> >> > When an UPDATE_FEATURES request fails, this new design provides better
> >> > clarity to the caller on which FeatureUpdate could not be applied (via
> >> the
> >> > individual error codes). In the previous design, we were unable to
> >> achieve
> >> > such an increased level of clarity in communicating the error codes.
> >> >
> >>
> >> OK
> >>
> >> >
> >> > 2. Due to #1, there were some minor changes required to the proposed
> >> Admin
> >> > APIs (describeFeatures and updateFeatures). A few unnecessary public
> >> APIs
> >> > have been removed, and couple essential ones have been added. The
> latest
> >> > changes now represent the latest design.
> >> >
> >> > 3. The timeoutMs field has been removed from the the UPDATE_FEATURES
> API
> >> > request, since it was not found to be required during implementation.
> >> >
> >>
> >> Please don't get rid of timeoutMs.  timeoutMs is required if you want to
> >> implement the ability to timeout the call if the controller can't get
> to it
> >> in time.  This is important for avoiding congestion collapse where the
> >> controller collapses under the weight of lots of retries of the same
> set of
> >> calls.
> >>
> >> We may not be able to do it in the initial implementation, but we will
> >> eventually implement this for all the controller-bound RPCs.
> >>
> >> > >
> >> > > 2. Finalized feature version epoch data type has been made to be
> int32
> >> > > (instead of int64). The reason is that the epoch value is the value
> >> of ZK
> >> > > node version, whose data type is int32.
> >> > >
> >>
> >> Sorry, I missed this earlier.  Using 16 bit feature levels seems fine.
> >> However, please don't use a 32-bit epoch here.  We deliberately made the
> >> epoch 64 bits to avoid overflow problems in the future once ZK is gone.
> >>
> >> best,
> >> Colin
> >>
> >> > > 3. Introduced a new 'status' field in the '/features' ZK node
> schema.
> >> The
> >> > > purpose is to implement Colin's earlier point for the strategy for
> >> > > transitioning from not having a /features znode to having one. An
> >> > > explanation has been provided in the following section of the KIP
> >> detailing
> >> > > the different cases:
> >> > >
> >>
> 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi Colin,

Thanks for the feedback. Those are very good points. I have made the
following changes to the KIP as you had suggested:
1. Included the `timeoutMs` field in the `UpdateFeaturesRequest` schema.
The initial implementation won't be making use of the field, but we can
always use it in the future as the need arises.
2. Modified the `FinalizedFeaturesEpoch` field in `ApiVersionsResponse` to
use int64. This is to avoid overflow problems in the future once ZK is gone.

I have also incorporated these changes into the versioning write path PR
that is currently under review: https://github.com/apache/kafka/pull/9001.


Cheers,
Kowshik



On Fri, Sep 25, 2020 at 4:57 PM Kowshik Prakasam 
wrote:

> Hi Jun,
>
> Thanks for the feedback. It's a very good point. I have now modified the
> KIP-584 write-up "goals" section a bit. It now mentions one of the goals as
> enabling rolling upgrades using a single restart (instead of 2). Also I
> have removed the text explicitly aiming for deprecation of IBP. Note that
> previously under "Potential features in Kafka" the IBP was mentioned under
> point (4) as a possible coarse-grained feature. Hopefully, now the 2
> sections of the KIP align with each other well.
>
>
> Cheers,
> Kowshik
>
>
> On Fri, Sep 25, 2020 at 2:03 PM Colin McCabe  wrote:
>
>> On Tue, Sep 22, 2020, at 00:43, Kowshik Prakasam wrote:
>> > Hi all,
>> >
>> > I wanted to let you know that I have made the following changes to the
>> > KIP-584 write up. The purpose is to ensure the design is correct for a
>> few
>> > things which came up during implementation:
>> >
>>
>> Hi Kowshik,
>>
>> Thanks for the updates.
>>
>> >
>> > 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller API is
>> no
>> > longer transactional. Going forward, we allow for individual
>> FeatureUpdate
>> > to succeed/fail in the request. As a result, the response schema now
>> > contains an error code per FeatureUpdate as well as a top-level error
>> code.
>> > Overall this is a better design because it better represents the nature
>> of
>> > the API: each FeatureUpdate in the request is independent of the other
>> > updates, and the controller can process/apply these independently to ZK.
>> > When an UPDATE_FEATURES request fails, this new design provides better
>> > clarity to the caller on which FeatureUpdate could not be applied (via
>> the
>> > individual error codes). In the previous design, we were unable to
>> achieve
>> > such an increased level of clarity in communicating the error codes.
>> >
>>
>> OK
>>
>> >
>> > 2. Due to #1, there were some minor changes required to the proposed
>> Admin
>> > APIs (describeFeatures and updateFeatures). A few unnecessary public
>> APIs
>> > have been removed, and couple essential ones have been added. The latest
>> > changes now represent the latest design.
>> >
>> > 3. The timeoutMs field has been removed from the the UPDATE_FEATURES API
>> > request, since it was not found to be required during implementation.
>> >
>>
>> Please don't get rid of timeoutMs.  timeoutMs is required if you want to
>> implement the ability to timeout the call if the controller can't get to it
>> in time.  This is important for avoiding congestion collapse where the
>> controller collapses under the weight of lots of retries of the same set of
>> calls.
>>
>> We may not be able to do it in the initial implementation, but we will
>> eventually implement this for all the controller-bound RPCs.
>>
>> > >
>> > > 2. Finalized feature version epoch data type has been made to be int32
>> > > (instead of int64). The reason is that the epoch value is the value
>> of ZK
>> > > node version, whose data type is int32.
>> > >
>>
>> Sorry, I missed this earlier.  Using 16 bit feature levels seems fine.
>> However, please don't use a 32-bit epoch here.  We deliberately made the
>> epoch 64 bits to avoid overflow problems in the future once ZK is gone.
>>
>> best,
>> Colin
>>
>> > > 3. Introduced a new 'status' field in the '/features' ZK node schema.
>> The
>> > > purpose is to implement Colin's earlier point for the strategy for
>> > > transitioning from not having a /features znode to having one. An
>> > > explanation has been provided in the following section of the KIP
>> detailing
>> > > the different cases:
>> > >
>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-FeatureZKnodestatus
>> > > .
>> > >
>> > > Please let me know if you have any questions or concerns.
>> > >
>> > >
>> > > Cheers,
>> > > Kowshik
>> > >
>> > >
>> > >
>> > > Cheers,
>> > > Kowshik
>> > >
>> > > On Tue, Apr 28, 2020 at 11:24 PM Kowshik Prakasam <
>> kpraka...@confluent.io>
>> > > wrote:
>> > >
>> > >> Hi all,
>> > >>
>> > >> This KIP vote has been open for ~12 days. The summary of the votes is
>> > >> that we have 3 binding votes (Colin, Guozhang, Jun), and 3
>> non-binding
>> > >> votes (David, Dhruvil, Boyang). Therefore, the KIP vote passes. I'll
>> mark

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi Jun,

Thanks for the feedback. It's a very good point. I have now modified the
KIP-584 write-up "goals" section a bit. It now mentions one of the goals as
enabling rolling upgrades using a single restart (instead of 2). Also I
have removed the text explicitly aiming for deprecation of IBP. Note that
previously under "Potential features in Kafka" the IBP was mentioned under
point (4) as a possible coarse-grained feature. Hopefully, now the 2
sections of the KIP align with each other well.


Cheers,
Kowshik


On Fri, Sep 25, 2020 at 2:03 PM Colin McCabe  wrote:

> On Tue, Sep 22, 2020, at 00:43, Kowshik Prakasam wrote:
> > Hi all,
> >
> > I wanted to let you know that I have made the following changes to the
> > KIP-584 write up. The purpose is to ensure the design is correct for a
> few
> > things which came up during implementation:
> >
>
> Hi Kowshik,
>
> Thanks for the updates.
>
> >
> > 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller API is no
> > longer transactional. Going forward, we allow for individual
> FeatureUpdate
> > to succeed/fail in the request. As a result, the response schema now
> > contains an error code per FeatureUpdate as well as a top-level error
> code.
> > Overall this is a better design because it better represents the nature
> of
> > the API: each FeatureUpdate in the request is independent of the other
> > updates, and the controller can process/apply these independently to ZK.
> > When an UPDATE_FEATURES request fails, this new design provides better
> > clarity to the caller on which FeatureUpdate could not be applied (via
> the
> > individual error codes). In the previous design, we were unable to
> achieve
> > such an increased level of clarity in communicating the error codes.
> >
>
> OK
>
> >
> > 2. Due to #1, there were some minor changes required to the proposed
> Admin
> > APIs (describeFeatures and updateFeatures). A few unnecessary public APIs
> > have been removed, and couple essential ones have been added. The latest
> > changes now represent the latest design.
> >
> > 3. The timeoutMs field has been removed from the the UPDATE_FEATURES API
> > request, since it was not found to be required during implementation.
> >
>
> Please don't get rid of timeoutMs.  timeoutMs is required if you want to
> implement the ability to timeout the call if the controller can't get to it
> in time.  This is important for avoiding congestion collapse where the
> controller collapses under the weight of lots of retries of the same set of
> calls.
>
> We may not be able to do it in the initial implementation, but we will
> eventually implement this for all the controller-bound RPCs.
>
> > >
> > > 2. Finalized feature version epoch data type has been made to be int32
> > > (instead of int64). The reason is that the epoch value is the value of
> ZK
> > > node version, whose data type is int32.
> > >
>
> Sorry, I missed this earlier.  Using 16 bit feature levels seems fine.
> However, please don't use a 32-bit epoch here.  We deliberately made the
> epoch 64 bits to avoid overflow problems in the future once ZK is gone.
>
> best,
> Colin
>
> > > 3. Introduced a new 'status' field in the '/features' ZK node schema.
> The
> > > purpose is to implement Colin's earlier point for the strategy for
> > > transitioning from not having a /features znode to having one. An
> > > explanation has been provided in the following section of the KIP
> detailing
> > > the different cases:
> > >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-FeatureZKnodestatus
> > > .
> > >
> > > Please let me know if you have any questions or concerns.
> > >
> > >
> > > Cheers,
> > > Kowshik
> > >
> > >
> > >
> > > Cheers,
> > > Kowshik
> > >
> > > On Tue, Apr 28, 2020 at 11:24 PM Kowshik Prakasam <
> kpraka...@confluent.io>
> > > wrote:
> > >
> > >> Hi all,
> > >>
> > >> This KIP vote has been open for ~12 days. The summary of the votes is
> > >> that we have 3 binding votes (Colin, Guozhang, Jun), and 3 non-binding
> > >> votes (David, Dhruvil, Boyang). Therefore, the KIP vote passes. I'll
> mark
> > >> KIP as accepted and start working on the implementation.
> > >>
> > >> Thanks a lot!
> > >>
> > >>
> > >> Cheers,
> > >> Kowshik
> > >>
> > >> On Mon, Apr 27, 2020 at 12:15 PM Colin McCabe 
> wrote:
> > >>
> > >>> Thanks, Kowshik.  +1 (binding)
> > >>>
> > >>> best,
> > >>> Colin
> > >>>
> > >>> On Sat, Apr 25, 2020, at 13:20, Kowshik Prakasam wrote:
> > >>> > Hi Colin,
> > >>> >
> > >>> > Thanks for the explanation! I agree with you, and I have updated
> the
> > >>> > KIP.
> > >>> > Here is a link to relevant section:
> > >>> >
> > >>>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP-584:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues
> > >>> >
> > >>> >
> > >>> > Cheers,
> > >>> > Kowshik
> > >>> >
> > >>> > On Fri, Apr 24, 2020 at 8:50 PM Colin 

Re: [VOTE] KIP-584: Versioning scheme for features

[Colin McCabe]

On Tue, Sep 22, 2020, at 00:43, Kowshik Prakasam wrote:
> Hi all,
> 
> I wanted to let you know that I have made the following changes to the
> KIP-584 write up. The purpose is to ensure the design is correct for a few
> things which came up during implementation:
>

Hi Kowshik,

Thanks for the updates.

> 
> 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller API is no
> longer transactional. Going forward, we allow for individual FeatureUpdate
> to succeed/fail in the request. As a result, the response schema now
> contains an error code per FeatureUpdate as well as a top-level error code.
> Overall this is a better design because it better represents the nature of
> the API: each FeatureUpdate in the request is independent of the other
> updates, and the controller can process/apply these independently to ZK.
> When an UPDATE_FEATURES request fails, this new design provides better
> clarity to the caller on which FeatureUpdate could not be applied (via the
> individual error codes). In the previous design, we were unable to achieve
> such an increased level of clarity in communicating the error codes.
> 

OK

>
> 2. Due to #1, there were some minor changes required to the proposed Admin
> APIs (describeFeatures and updateFeatures). A few unnecessary public APIs
> have been removed, and couple essential ones have been added. The latest
> changes now represent the latest design.
> 
> 3. The timeoutMs field has been removed from the the UPDATE_FEATURES API
> request, since it was not found to be required during implementation.
> 

Please don't get rid of timeoutMs.  timeoutMs is required if you want to 
implement the ability to timeout the call if the controller can't get to it in 
time.  This is important for avoiding congestion collapse where the controller 
collapses under the weight of lots of retries of the same set of calls.

We may not be able to do it in the initial implementation, but we will 
eventually implement this for all the controller-bound RPCs.

> >
> > 2. Finalized feature version epoch data type has been made to be int32
> > (instead of int64). The reason is that the epoch value is the value of ZK
> > node version, whose data type is int32.
> >

Sorry, I missed this earlier.  Using 16 bit feature levels seems fine.  
However, please don't use a 32-bit epoch here.  We deliberately made the epoch 
64 bits to avoid overflow problems in the future once ZK is gone.

best,
Colin

> > 3. Introduced a new 'status' field in the '/features' ZK node schema. The
> > purpose is to implement Colin's earlier point for the strategy for
> > transitioning from not having a /features znode to having one. An
> > explanation has been provided in the following section of the KIP detailing
> > the different cases:
> > https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-FeatureZKnodestatus
> > .
> >
> > Please let me know if you have any questions or concerns.
> >
> >
> > Cheers,
> > Kowshik
> >
> >
> >
> > Cheers,
> > Kowshik
> >
> > On Tue, Apr 28, 2020 at 11:24 PM Kowshik Prakasam 
> > wrote:
> >
> >> Hi all,
> >>
> >> This KIP vote has been open for ~12 days. The summary of the votes is
> >> that we have 3 binding votes (Colin, Guozhang, Jun), and 3 non-binding
> >> votes (David, Dhruvil, Boyang). Therefore, the KIP vote passes. I'll mark
> >> KIP as accepted and start working on the implementation.
> >>
> >> Thanks a lot!
> >>
> >>
> >> Cheers,
> >> Kowshik
> >>
> >> On Mon, Apr 27, 2020 at 12:15 PM Colin McCabe  wrote:
> >>
> >>> Thanks, Kowshik.  +1 (binding)
> >>>
> >>> best,
> >>> Colin
> >>>
> >>> On Sat, Apr 25, 2020, at 13:20, Kowshik Prakasam wrote:
> >>> > Hi Colin,
> >>> >
> >>> > Thanks for the explanation! I agree with you, and I have updated the
> >>> > KIP.
> >>> > Here is a link to relevant section:
> >>> >
> >>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP-584:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues
> >>> >
> >>> >
> >>> > Cheers,
> >>> > Kowshik
> >>> >
> >>> > On Fri, Apr 24, 2020 at 8:50 PM Colin McCabe 
> >>> wrote:
> >>> >
> >>> > > On Fri, Apr 24, 2020, at 00:01, Kowshik Prakasam wrote:
> >>> > > > (Kowshik): Great point! However for case #1, I'm not sure why we
> >>> need to
> >>> > > > create a '/features' ZK node with disabled features. Instead, do
> >>> you see
> >>> > > > any drawback if we just do not create it? i.e. if IBP is less than
> >>> 2.6,
> >>> > > the
> >>> > > > controller treats the case as though the versioning system is
> >>> completely
> >>> > > > disabled, and would not create a non-existing '/features' node.
> >>> > >
> >>> > > Hi Kowshik,
> >>> > >
> >>> > > When the IBP is less than 2.6, but the software has been upgraded to
> >>> a
> >>> > > state where it supports this KIP, that
> >>> > >  means the user is upgrading from an earlier version of the
> >>> software.  In
> >>> > > this case, 

Re: [VOTE] KIP-584: Versioning scheme for features

[Jun Rao]

Hi, Kowshik,

Thanks for the update. Those changes seem fine to me.

One of the goals listed in this KIP is the removal of IBP in the future.
Recent discussion in KIP-590 intends to expand the scope of IBP for
forwarding requests to the controller. In light of this, is the goal of
removing IBP still valid?

Thanks,

Jun

On Tue, Sep 22, 2020 at 12:43 AM Kowshik Prakasam 
wrote:

> Hi all,
>
> I wanted to let you know that I have made the following changes to the
> KIP-584 write up. The purpose is to ensure the design is correct for a few
> things which came up during implementation:
>
> 1. Per FeatureUpdate error code: The UPDATE_FEATURES controller API is no
> longer transactional. Going forward, we allow for individual FeatureUpdate
> to succeed/fail in the request. As a result, the response schema now
> contains an error code per FeatureUpdate as well as a top-level error code.
> Overall this is a better design because it better represents the nature of
> the API: each FeatureUpdate in the request is independent of the other
> updates, and the controller can process/apply these independently to ZK.
> When an UPDATE_FEATURES request fails, this new design provides better
> clarity to the caller on which FeatureUpdate could not be applied (via the
> individual error codes). In the previous design, we were unable to achieve
> such an increased level of clarity in communicating the error codes.
>
> 2. Due to #1, there were some minor changes required to the proposed Admin
> APIs (describeFeatures and updateFeatures). A few unnecessary public APIs
> have been removed, and couple essential ones have been added. The latest
> changes now represent the latest design.
>
> 3. The timeoutMs field has been removed from the the UPDATE_FEATURES API
> request, since it was not found to be required during implementation.
>
> 4. Previously we handled the incompatible broker lifetime race condition in
> the controller by skipping sending of UpdateMetadataRequest to the
> incompatible broker. But this had a few edge cases. Instead, now we handle
> it by refusing to register the incompatible broker in the controller. This
> is a better design because if we already acted on an incompatible broker
> registration, then some damage may already be done to the cluster. This is
> because the UpdatateMetadataRequest will still be sent to other brokers and
> its metadata will be available to the clients. Therefore we would like to
> avoid this problem with the new design where the controller would not keep
> track of an incompatible broker because the broker will eventually shutdown
> automatically (when reacting to the incompatibility).
>
> Please let me know if you have any questions.
>
>
> Cheers,
> Kowshik
>
>
> On Mon, Jun 8, 2020 at 3:32 AM Kowshik Prakasam 
> wrote:
>
> > Hi all,
> >
> > I wanted to let you know that I have made the following minor changes to
> > the KIP-584  write up.
> The
> > purpose is to ensure the design is correct for a few things which came up
> > during implementation:
> >
> > 1. Feature version data type has been made to be int16 (instead of
> int64).
> > The reason is two fold:
> > a. Usage of int64 felt overkill. Feature version bumps are infrequent
> > (since these bumps represent breaking changes that are generally
> > infrequent). Therefore int16 is big enough to support version bumps of a
> > particular feature.
> > b. The int16 data type aligns well with existing API versions data
> > type. Please see the file
> >
> '/clients/src/main/resources/common/message/ApiVersionsResponse.json'.
> >
> > 2. Finalized feature version epoch data type has been made to be int32
> > (instead of int64). The reason is that the epoch value is the value of ZK
> > node version, whose data type is int32.
> >
> > 3. Introduced a new 'status' field in the '/features' ZK node schema. The
> > purpose is to implement Colin's earlier point for the strategy for
> > transitioning from not having a /features znode to having one. An
> > explanation has been provided in the following section of the KIP
> detailing
> > the different cases:
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-FeatureZKnodestatus
> > .
> >
> > Please let me know if you have any questions or concerns.
> >
> >
> > Cheers,
> > Kowshik
> >
> >
> >
> > Cheers,
> > Kowshik
> >
> > On Tue, Apr 28, 2020 at 11:24 PM Kowshik Prakasam <
> kpraka...@confluent.io>
> > wrote:
> >
> >> Hi all,
> >>
> >> This KIP vote has been open for ~12 days. The summary of the votes is
> >> that we have 3 binding votes (Colin, Guozhang, Jun), and 3 non-binding
> >> votes (David, Dhruvil, Boyang). Therefore, the KIP vote passes. I'll
> mark
> >> KIP as accepted and start working on the implementation.
> >>
> >> Thanks a lot!
> >>
> >>
> >> Cheers,
> >> Kowshik
> >>
> >> On Mon, Apr 27, 2020 at 12:15 PM Colin McCabe 
> wrote:
> >>
> >>> 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi all,

I wanted to let you know that I have made the following changes to the
KIP-584 write up. The purpose is to ensure the design is correct for a few
things which came up during implementation:

1. Per FeatureUpdate error code: The UPDATE_FEATURES controller API is no
longer transactional. Going forward, we allow for individual FeatureUpdate
to succeed/fail in the request. As a result, the response schema now
contains an error code per FeatureUpdate as well as a top-level error code.
Overall this is a better design because it better represents the nature of
the API: each FeatureUpdate in the request is independent of the other
updates, and the controller can process/apply these independently to ZK.
When an UPDATE_FEATURES request fails, this new design provides better
clarity to the caller on which FeatureUpdate could not be applied (via the
individual error codes). In the previous design, we were unable to achieve
such an increased level of clarity in communicating the error codes.

2. Due to #1, there were some minor changes required to the proposed Admin
APIs (describeFeatures and updateFeatures). A few unnecessary public APIs
have been removed, and couple essential ones have been added. The latest
changes now represent the latest design.

3. The timeoutMs field has been removed from the the UPDATE_FEATURES API
request, since it was not found to be required during implementation.

4. Previously we handled the incompatible broker lifetime race condition in
the controller by skipping sending of UpdateMetadataRequest to the
incompatible broker. But this had a few edge cases. Instead, now we handle
it by refusing to register the incompatible broker in the controller. This
is a better design because if we already acted on an incompatible broker
registration, then some damage may already be done to the cluster. This is
because the UpdatateMetadataRequest will still be sent to other brokers and
its metadata will be available to the clients. Therefore we would like to
avoid this problem with the new design where the controller would not keep
track of an incompatible broker because the broker will eventually shutdown
automatically (when reacting to the incompatibility).

Please let me know if you have any questions.


Cheers,
Kowshik


On Mon, Jun 8, 2020 at 3:32 AM Kowshik Prakasam 
wrote:

> Hi all,
>
> I wanted to let you know that I have made the following minor changes to
> the KIP-584  write up. The
> purpose is to ensure the design is correct for a few things which came up
> during implementation:
>
> 1. Feature version data type has been made to be int16 (instead of int64).
> The reason is two fold:
> a. Usage of int64 felt overkill. Feature version bumps are infrequent
> (since these bumps represent breaking changes that are generally
> infrequent). Therefore int16 is big enough to support version bumps of a
> particular feature.
> b. The int16 data type aligns well with existing API versions data
> type. Please see the file
> '/clients/src/main/resources/common/message/ApiVersionsResponse.json'.
>
> 2. Finalized feature version epoch data type has been made to be int32
> (instead of int64). The reason is that the epoch value is the value of ZK
> node version, whose data type is int32.
>
> 3. Introduced a new 'status' field in the '/features' ZK node schema. The
> purpose is to implement Colin's earlier point for the strategy for
> transitioning from not having a /features znode to having one. An
> explanation has been provided in the following section of the KIP detailing
> the different cases:
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-FeatureZKnodestatus
> .
>
> Please let me know if you have any questions or concerns.
>
>
> Cheers,
> Kowshik
>
>
>
> Cheers,
> Kowshik
>
> On Tue, Apr 28, 2020 at 11:24 PM Kowshik Prakasam 
> wrote:
>
>> Hi all,
>>
>> This KIP vote has been open for ~12 days. The summary of the votes is
>> that we have 3 binding votes (Colin, Guozhang, Jun), and 3 non-binding
>> votes (David, Dhruvil, Boyang). Therefore, the KIP vote passes. I'll mark
>> KIP as accepted and start working on the implementation.
>>
>> Thanks a lot!
>>
>>
>> Cheers,
>> Kowshik
>>
>> On Mon, Apr 27, 2020 at 12:15 PM Colin McCabe  wrote:
>>
>>> Thanks, Kowshik.  +1 (binding)
>>>
>>> best,
>>> Colin
>>>
>>> On Sat, Apr 25, 2020, at 13:20, Kowshik Prakasam wrote:
>>> > Hi Colin,
>>> >
>>> > Thanks for the explanation! I agree with you, and I have updated the
>>> > KIP.
>>> > Here is a link to relevant section:
>>> >
>>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP-584:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues
>>> >
>>> >
>>> > Cheers,
>>> > Kowshik
>>> >
>>> > On Fri, Apr 24, 2020 at 8:50 PM Colin McCabe 
>>> wrote:
>>> >
>>> > > On Fri, Apr 24, 2020, at 00:01, Kowshik Prakasam wrote:

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi all,

I wanted to let you know that I have made the following minor changes to
the KIP-584 write up. The purpose is to ensure the design is correct for a
few things which came up during implementation:

1. Feature version data type has been made to be int16 (instead of int64).
The reason is two fold:
a. Usage of int64 felt overkill. Feature version bumps are infrequent
(since these bumps represent breaking changes that are generally
infrequent). Therefore int16 is big enough to support version bumps of a
particular feature.
b. The int16 data type aligns well with existing API versions data
type. Please see the file
'/clients/src/main/resources/common/message/ApiVersionsResponse.json'.

2. Finalized feature version epoch data type has been made to be int32
(instead of int64). The reason is that the epoch value is the value of ZK
node version, whose data type is int32.

3. Introduced a new 'status' field in the '/features' ZK node schema. The
purpose is to implement Colin's earlier point for the strategy for
transitioning from not having a /features znode to having one. An
explanation has been provided in the following section of the KIP detailing
the different cases:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP584:Versioningschemeforfeatures-FeatureZKnodestatus
.

Please let me know if you have any questions or concerns.


Cheers,
Kowshik



Cheers,
Kowshik

On Tue, Apr 28, 2020 at 11:24 PM Kowshik Prakasam 
wrote:

> Hi all,
>
> This KIP vote has been open for ~12 days. The summary of the votes is that
> we have 3 binding votes (Colin, Guozhang, Jun), and 3 non-binding votes
> (David, Dhruvil, Boyang). Therefore, the KIP vote passes. I'll mark KIP as
> accepted and start working on the implementation.
>
> Thanks a lot!
>
>
> Cheers,
> Kowshik
>
> On Mon, Apr 27, 2020 at 12:15 PM Colin McCabe  wrote:
>
>> Thanks, Kowshik.  +1 (binding)
>>
>> best,
>> Colin
>>
>> On Sat, Apr 25, 2020, at 13:20, Kowshik Prakasam wrote:
>> > Hi Colin,
>> >
>> > Thanks for the explanation! I agree with you, and I have updated the
>> > KIP.
>> > Here is a link to relevant section:
>> >
>> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP-584:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues
>> >
>> >
>> > Cheers,
>> > Kowshik
>> >
>> > On Fri, Apr 24, 2020 at 8:50 PM Colin McCabe 
>> wrote:
>> >
>> > > On Fri, Apr 24, 2020, at 00:01, Kowshik Prakasam wrote:
>> > > > (Kowshik): Great point! However for case #1, I'm not sure why we
>> need to
>> > > > create a '/features' ZK node with disabled features. Instead, do
>> you see
>> > > > any drawback if we just do not create it? i.e. if IBP is less than
>> 2.6,
>> > > the
>> > > > controller treats the case as though the versioning system is
>> completely
>> > > > disabled, and would not create a non-existing '/features' node.
>> > >
>> > > Hi Kowshik,
>> > >
>> > > When the IBP is less than 2.6, but the software has been upgraded to a
>> > > state where it supports this KIP, that
>> > >  means the user is upgrading from an earlier version of the
>> software.  In
>> > > this case, we want to start with all the features disabled and allow
>> the
>> > > user to enable them when they are ready.
>> > >
>> > > Enabling all the possible features immediately after an upgrade could
>> be
>> > > harmful to the cluster.  On the other hand, for a new cluster, we do
>> want
>> > > to enable all the possible features immediately . I was proposing
>> this as a
>> > > way to distinguish the two cases (since the new cluster will never be
>> > > started with an old IBP).
>> > >
>> > > > Colin MccCabe wrote:
>> > > > > And now, something a little bit bigger (sorry).  For finalized
>> > > features,
>> > > > > why do we need both min_version_level and max_version_level?
>> Assuming
>> > > that
>> > > > > we want all the brokers to be on the same feature version level,
>> we
>> > > really only care
>> > > > > about three numbers for each feature, right?  The minimum
>> supported
>> > > version
>> > > > > level, the maximum supported version level, and the current active
>> > > version level.
>> > > >
>> > > > > We don't actually want different brokers to be on different
>> versions of
>> > > > > the same feature, right?  So we can just have one number for
>> current
>> > > > > version level, rather than two.  At least that's what I was
>> thinking
>> > > -- let
>> > > > > me know if I missed something.
>> > > >
>> > > > (Kowshik): It is my understanding that the "current active version
>> level"
>> > > > that you have mentioned, is the "max_version_level". But we still
>> > > > maintain/publish both min and max version levels, because, the
>> detail
>> > > about
>> > > > min level is useful to external clients. This is described below.
>> > > >
>> > > > For any feature F, think of the closed range: [min_version_level,
>> > > > max_version_level] as the range of finalized 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi all,

This KIP vote has been open for ~12 days. The summary of the votes is that
we have 3 binding votes (Colin, Guozhang, Jun), and 3 non-binding votes
(David, Dhruvil, Boyang). Therefore, the KIP vote passes. I'll mark KIP as
accepted and start working on the implementation.

Thanks a lot!


Cheers,
Kowshik

On Mon, Apr 27, 2020 at 12:15 PM Colin McCabe  wrote:

> Thanks, Kowshik.  +1 (binding)
>
> best,
> Colin
>
> On Sat, Apr 25, 2020, at 13:20, Kowshik Prakasam wrote:
> > Hi Colin,
> >
> > Thanks for the explanation! I agree with you, and I have updated the
> > KIP.
> > Here is a link to relevant section:
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP-584:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues
> >
> >
> > Cheers,
> > Kowshik
> >
> > On Fri, Apr 24, 2020 at 8:50 PM Colin McCabe  wrote:
> >
> > > On Fri, Apr 24, 2020, at 00:01, Kowshik Prakasam wrote:
> > > > (Kowshik): Great point! However for case #1, I'm not sure why we
> need to
> > > > create a '/features' ZK node with disabled features. Instead, do you
> see
> > > > any drawback if we just do not create it? i.e. if IBP is less than
> 2.6,
> > > the
> > > > controller treats the case as though the versioning system is
> completely
> > > > disabled, and would not create a non-existing '/features' node.
> > >
> > > Hi Kowshik,
> > >
> > > When the IBP is less than 2.6, but the software has been upgraded to a
> > > state where it supports this KIP, that
> > >  means the user is upgrading from an earlier version of the software.
> In
> > > this case, we want to start with all the features disabled and allow
> the
> > > user to enable them when they are ready.
> > >
> > > Enabling all the possible features immediately after an upgrade could
> be
> > > harmful to the cluster.  On the other hand, for a new cluster, we do
> want
> > > to enable all the possible features immediately . I was proposing this
> as a
> > > way to distinguish the two cases (since the new cluster will never be
> > > started with an old IBP).
> > >
> > > > Colin MccCabe wrote:
> > > > > And now, something a little bit bigger (sorry).  For finalized
> > > features,
> > > > > why do we need both min_version_level and max_version_level?
> Assuming
> > > that
> > > > > we want all the brokers to be on the same feature version level, we
> > > really only care
> > > > > about three numbers for each feature, right?  The minimum supported
> > > version
> > > > > level, the maximum supported version level, and the current active
> > > version level.
> > > >
> > > > > We don't actually want different brokers to be on different
> versions of
> > > > > the same feature, right?  So we can just have one number for
> current
> > > > > version level, rather than two.  At least that's what I was
> thinking
> > > -- let
> > > > > me know if I missed something.
> > > >
> > > > (Kowshik): It is my understanding that the "current active version
> level"
> > > > that you have mentioned, is the "max_version_level". But we still
> > > > maintain/publish both min and max version levels, because, the detail
> > > about
> > > > min level is useful to external clients. This is described below.
> > > >
> > > > For any feature F, think of the closed range: [min_version_level,
> > > > max_version_level] as the range of finalized versions, that's
> guaranteed
> > > to
> > > > be supported by all brokers in the cluster.
> > > >  - "max_version_level" is the finalized highest common version among
> all
> > > > brokers,
> > > >  - "min_version_level" is the finalized lowest common version among
> all
> > > > brokers.
> > > >
> > > > Next, think of "client" here as the "user of the new feature versions
> > > > system". Imagine that such a client learns about finalized feature
> > > > versions, and exercises some logic based on the version. These
> clients
> > > can
> > > > be of 2 types:
> > > > 1. Some part of the broker code itself could behave like a client
> trying
> > > to
> > > > use some feature that's "internal" to the broker cluster. Such a
> client
> > > > would learn the latest finalized features via ZK.
> > > > 2. An external system (ex: Streams) could behave like a client,
> trying to
> > > > use some "external" facing feature. Such a client would learn latest
> > > > finalized features via ApiVersionsRequest. Ex: group_coordinator
> feature
> > > > described in the KIP.
> > > >
> > > > Next, imagine that for F, the max_version_level is successfully
> bumped by
> > > > +1 (via Controller API). Now it is guaranteed that all brokers (i.e.
> > > > internal clients) understand max_version_level + 1. However, it is
> still
> > > > not guaranteed that all external clients have support for (or have
> > > > activated) the logic for the newer version. Why? Because, this is
> > > > subjective as explained next:
> > > >
> > > > 1. On one hand, imagine F as an internal feature only relevant to
> > > Brokers.
> > > > The 

Re: [VOTE] KIP-584: Versioning scheme for features

[Colin McCabe]

Thanks, Kowshik.  +1 (binding)

best,
Colin

On Sat, Apr 25, 2020, at 13:20, Kowshik Prakasam wrote:
> Hi Colin,
> 
> Thanks for the explanation! I agree with you, and I have updated the 
> KIP.
> Here is a link to relevant section:
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP-584:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues
> 
> 
> Cheers,
> Kowshik
> 
> On Fri, Apr 24, 2020 at 8:50 PM Colin McCabe  wrote:
> 
> > On Fri, Apr 24, 2020, at 00:01, Kowshik Prakasam wrote:
> > > (Kowshik): Great point! However for case #1, I'm not sure why we need to
> > > create a '/features' ZK node with disabled features. Instead, do you see
> > > any drawback if we just do not create it? i.e. if IBP is less than 2.6,
> > the
> > > controller treats the case as though the versioning system is completely
> > > disabled, and would not create a non-existing '/features' node.
> >
> > Hi Kowshik,
> >
> > When the IBP is less than 2.6, but the software has been upgraded to a
> > state where it supports this KIP, that
> >  means the user is upgrading from an earlier version of the software.  In
> > this case, we want to start with all the features disabled and allow the
> > user to enable them when they are ready.
> >
> > Enabling all the possible features immediately after an upgrade could be
> > harmful to the cluster.  On the other hand, for a new cluster, we do want
> > to enable all the possible features immediately . I was proposing this as a
> > way to distinguish the two cases (since the new cluster will never be
> > started with an old IBP).
> >
> > > Colin MccCabe wrote:
> > > > And now, something a little bit bigger (sorry).  For finalized
> > features,
> > > > why do we need both min_version_level and max_version_level?  Assuming
> > that
> > > > we want all the brokers to be on the same feature version level, we
> > really only care
> > > > about three numbers for each feature, right?  The minimum supported
> > version
> > > > level, the maximum supported version level, and the current active
> > version level.
> > >
> > > > We don't actually want different brokers to be on different versions of
> > > > the same feature, right?  So we can just have one number for current
> > > > version level, rather than two.  At least that's what I was thinking
> > -- let
> > > > me know if I missed something.
> > >
> > > (Kowshik): It is my understanding that the "current active version level"
> > > that you have mentioned, is the "max_version_level". But we still
> > > maintain/publish both min and max version levels, because, the detail
> > about
> > > min level is useful to external clients. This is described below.
> > >
> > > For any feature F, think of the closed range: [min_version_level,
> > > max_version_level] as the range of finalized versions, that's guaranteed
> > to
> > > be supported by all brokers in the cluster.
> > >  - "max_version_level" is the finalized highest common version among all
> > > brokers,
> > >  - "min_version_level" is the finalized lowest common version among all
> > > brokers.
> > >
> > > Next, think of "client" here as the "user of the new feature versions
> > > system". Imagine that such a client learns about finalized feature
> > > versions, and exercises some logic based on the version. These clients
> > can
> > > be of 2 types:
> > > 1. Some part of the broker code itself could behave like a client trying
> > to
> > > use some feature that's "internal" to the broker cluster. Such a client
> > > would learn the latest finalized features via ZK.
> > > 2. An external system (ex: Streams) could behave like a client, trying to
> > > use some "external" facing feature. Such a client would learn latest
> > > finalized features via ApiVersionsRequest. Ex: group_coordinator feature
> > > described in the KIP.
> > >
> > > Next, imagine that for F, the max_version_level is successfully bumped by
> > > +1 (via Controller API). Now it is guaranteed that all brokers (i.e.
> > > internal clients) understand max_version_level + 1. However, it is still
> > > not guaranteed that all external clients have support for (or have
> > > activated) the logic for the newer version. Why? Because, this is
> > > subjective as explained next:
> > >
> > > 1. On one hand, imagine F as an internal feature only relevant to
> > Brokers.
> > > The binary for the internal client logic is controlled by Broker cluster
> > > deployments. When shipping a new Broker release, we wouldn't bump max
> > > "supported" feature version for F by 1, unless we have introduced some
> > new
> > > logic (with a potentially breaking change) in the Broker. Furthermore,
> > such
> > > feature logic in the broker should/will not be implemented in a way that
> > it
> > > would activate logic for an older feature version after it has migrated
> > to
> > > using the logic for a newer feature version (because this could break the
> > > cluster!). For these cases, 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi Colin,

Thanks for the explanation! I agree with you, and I have updated the KIP.
Here is a link to relevant section:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features#KIP-584:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues


Cheers,
Kowshik

On Fri, Apr 24, 2020 at 8:50 PM Colin McCabe  wrote:

> On Fri, Apr 24, 2020, at 00:01, Kowshik Prakasam wrote:
> > (Kowshik): Great point! However for case #1, I'm not sure why we need to
> > create a '/features' ZK node with disabled features. Instead, do you see
> > any drawback if we just do not create it? i.e. if IBP is less than 2.6,
> the
> > controller treats the case as though the versioning system is completely
> > disabled, and would not create a non-existing '/features' node.
>
> Hi Kowshik,
>
> When the IBP is less than 2.6, but the software has been upgraded to a
> state where it supports this KIP, that
>  means the user is upgrading from an earlier version of the software.  In
> this case, we want to start with all the features disabled and allow the
> user to enable them when they are ready.
>
> Enabling all the possible features immediately after an upgrade could be
> harmful to the cluster.  On the other hand, for a new cluster, we do want
> to enable all the possible features immediately . I was proposing this as a
> way to distinguish the two cases (since the new cluster will never be
> started with an old IBP).
>
> > Colin MccCabe wrote:
> > > And now, something a little bit bigger (sorry).  For finalized
> features,
> > > why do we need both min_version_level and max_version_level?  Assuming
> that
> > > we want all the brokers to be on the same feature version level, we
> really only care
> > > about three numbers for each feature, right?  The minimum supported
> version
> > > level, the maximum supported version level, and the current active
> version level.
> >
> > > We don't actually want different brokers to be on different versions of
> > > the same feature, right?  So we can just have one number for current
> > > version level, rather than two.  At least that's what I was thinking
> -- let
> > > me know if I missed something.
> >
> > (Kowshik): It is my understanding that the "current active version level"
> > that you have mentioned, is the "max_version_level". But we still
> > maintain/publish both min and max version levels, because, the detail
> about
> > min level is useful to external clients. This is described below.
> >
> > For any feature F, think of the closed range: [min_version_level,
> > max_version_level] as the range of finalized versions, that's guaranteed
> to
> > be supported by all brokers in the cluster.
> >  - "max_version_level" is the finalized highest common version among all
> > brokers,
> >  - "min_version_level" is the finalized lowest common version among all
> > brokers.
> >
> > Next, think of "client" here as the "user of the new feature versions
> > system". Imagine that such a client learns about finalized feature
> > versions, and exercises some logic based on the version. These clients
> can
> > be of 2 types:
> > 1. Some part of the broker code itself could behave like a client trying
> to
> > use some feature that's "internal" to the broker cluster. Such a client
> > would learn the latest finalized features via ZK.
> > 2. An external system (ex: Streams) could behave like a client, trying to
> > use some "external" facing feature. Such a client would learn latest
> > finalized features via ApiVersionsRequest. Ex: group_coordinator feature
> > described in the KIP.
> >
> > Next, imagine that for F, the max_version_level is successfully bumped by
> > +1 (via Controller API). Now it is guaranteed that all brokers (i.e.
> > internal clients) understand max_version_level + 1. However, it is still
> > not guaranteed that all external clients have support for (or have
> > activated) the logic for the newer version. Why? Because, this is
> > subjective as explained next:
> >
> > 1. On one hand, imagine F as an internal feature only relevant to
> Brokers.
> > The binary for the internal client logic is controlled by Broker cluster
> > deployments. When shipping a new Broker release, we wouldn't bump max
> > "supported" feature version for F by 1, unless we have introduced some
> new
> > logic (with a potentially breaking change) in the Broker. Furthermore,
> such
> > feature logic in the broker should/will not be implemented in a way that
> it
> > would activate logic for an older feature version after it has migrated
> to
> > using the logic for a newer feature version (because this could break the
> > cluster!). For these cases, max_version_level will be very useful for
> > decision making.
> >
> > 2. On the other hand, imagine F as an external facing feature. External
> > clients are not within the control of Broker cluster. An external client
> > may not have upgraded it's code (yet) to use 'max_version_level + 1'.
> But,
> > the Kafka 

Re: [VOTE] KIP-584: Versioning scheme for features

[Colin McCabe]

On Fri, Apr 24, 2020, at 00:01, Kowshik Prakasam wrote:
> (Kowshik): Great point! However for case #1, I'm not sure why we need to
> create a '/features' ZK node with disabled features. Instead, do you see
> any drawback if we just do not create it? i.e. if IBP is less than 2.6, the
> controller treats the case as though the versioning system is completely
> disabled, and would not create a non-existing '/features' node.

Hi Kowshik,

When the IBP is less than 2.6, but the software has been upgraded to a state 
where it supports this KIP, that 
 means the user is upgrading from an earlier version of the software.  In this 
case, we want to start with all the features disabled and allow the user to 
enable them when they are ready.

Enabling all the possible features immediately after an upgrade could be 
harmful to the cluster.  On the other hand, for a new cluster, we do want to 
enable all the possible features immediately . I was proposing this as a way to 
distinguish the two cases (since the new cluster will never be started with an 
old IBP).

> Colin MccCabe wrote:
> > And now, something a little bit bigger (sorry).  For finalized features,
> > why do we need both min_version_level and max_version_level?  Assuming that
> > we want all the brokers to be on the same feature version level, we really 
> > only care
> > about three numbers for each feature, right?  The minimum supported version
> > level, the maximum supported version level, and the current active version 
> > level.
> 
> > We don't actually want different brokers to be on different versions of
> > the same feature, right?  So we can just have one number for current
> > version level, rather than two.  At least that's what I was thinking -- let
> > me know if I missed something.
> 
> (Kowshik): It is my understanding that the "current active version level"
> that you have mentioned, is the "max_version_level". But we still
> maintain/publish both min and max version levels, because, the detail about
> min level is useful to external clients. This is described below.
> 
> For any feature F, think of the closed range: [min_version_level,
> max_version_level] as the range of finalized versions, that's guaranteed to
> be supported by all brokers in the cluster.
>  - "max_version_level" is the finalized highest common version among all
> brokers,
>  - "min_version_level" is the finalized lowest common version among all
> brokers.
> 
> Next, think of "client" here as the "user of the new feature versions
> system". Imagine that such a client learns about finalized feature
> versions, and exercises some logic based on the version. These clients can
> be of 2 types:
> 1. Some part of the broker code itself could behave like a client trying to
> use some feature that's "internal" to the broker cluster. Such a client
> would learn the latest finalized features via ZK.
> 2. An external system (ex: Streams) could behave like a client, trying to
> use some "external" facing feature. Such a client would learn latest
> finalized features via ApiVersionsRequest. Ex: group_coordinator feature
> described in the KIP.
> 
> Next, imagine that for F, the max_version_level is successfully bumped by
> +1 (via Controller API). Now it is guaranteed that all brokers (i.e.
> internal clients) understand max_version_level + 1. However, it is still
> not guaranteed that all external clients have support for (or have
> activated) the logic for the newer version. Why? Because, this is
> subjective as explained next:
> 
> 1. On one hand, imagine F as an internal feature only relevant to Brokers.
> The binary for the internal client logic is controlled by Broker cluster
> deployments. When shipping a new Broker release, we wouldn't bump max
> "supported" feature version for F by 1, unless we have introduced some new
> logic (with a potentially breaking change) in the Broker. Furthermore, such
> feature logic in the broker should/will not be implemented in a way that it
> would activate logic for an older feature version after it has migrated to
> using the logic for a newer feature version (because this could break the
> cluster!). For these cases, max_version_level will be very useful for
> decision making.
> 
> 2. On the other hand, imagine F as an external facing feature. External
> clients are not within the control of Broker cluster. An external client
> may not have upgraded it's code (yet) to use 'max_version_level + 1'. But,
> the Kafka cluster could have been deployed with support for
> 'max_version_level + 1' of an external facing feature. Now, these external
> clients (until an upgrade) are benefitted in learning "what is the lowest
> common version for F among all brokers?". This is where the
> "min_version_level" becomes useful. Using this, a client could learn the
> specific supported versions that's lower than max_version_level (instead of
> assuming that all brokers support the range: [1, max_version_level]). For
> example, if the cluster deprecates 

Re: [VOTE] KIP-584: Versioning scheme for features

[Kowshik Prakasam]

Hi Colin,

Thanks a lot for the excellent feedback and great
ideas/questions/suggestions. I have updated the KIP based on the feedback.
Please find my response below to the comments.

> It would be good to note that deprecating a feature version (in other
words, increasing minVersionLevel on the broker) is an incompatible
> change, which requires a major release of Kafka.

(Kowshik): Great point! Done. I have updated the KIP mentioning this in
'Non-goals' as well as 'Feature version deprecation' sections.

===

> I think the strategy for transitioning from not having a /features znode
to having one could use some work. The current proposal is to wait for all
the
> brokers to fill in their feature znodes and then pick the highest common
versions.  But that requires blocking in the controller startup code until
the
> whole cluster is active (technically, a point in time which we never
really know that we have reached...)

> Instead, I think it would be better to have a strategy like this:
> 1. If the controller comes up and there is no /features znode AND the IBP
is less than 2.6, create a /features znode where all the features are
disabled.
> 2. If the controller comes up and there is no /features znode AND the IBP
is greater than or equal to 2.6, create a /features znode where all the
> features are enabled at the highest versions supported by the controller.

> People upgrading from the pre-KIP-584
 world will end up in case
#1 because they have to do a double roll to upgrade, and during the first
roll, the IBP
> is unchanged.  People creating new clusters from scratch will end up in
case #2, which is what we want since we don't want a brand new cluster to be
> using old feature flag versions.

(Kowshik): Great point! However for case #1, I'm not sure why we need to
create a '/features' ZK node with disabled features. Instead, do you see
any drawback if we just do not create it? i.e. if IBP is less than 2.6, the
controller treats the case as though the versioning system is completely
disabled, and would not create a non-existing '/features' node.

I have updated the KIP with your suggestions, please refer to this section:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-584

%3A+Versioning+scheme+for+features#KIP-584

:Versioningschemeforfeatures-Controller:ZKnodebootstrapwithdefaultvalues


===

> UpdateFeaturesResponse#ErrorMessage should specify nullableVersions since
null is a valid value here
> Also, in the message format, the tags we use need to start at 0.

(Kowshik): Great point! Done.

===

> I don't think we need the FEATURE_UPDATE_IN_PROGRESS error code.  The
controller is basically single-threaded and will only do one of these
operations at once.  Even
> if it weren't, though, we could simply block the second operation behind
the first one.

(Kowshik): Great point! Done, eliminated now.

===

> For updateFeatures, it would be good to specify that if a single feature
version update in the batch can't be done, none of them are done.  I think
this was the
>intention, but I wasn't able to find it spelled out (maybe i missed it).

(Kowshik): Done. I have changed the wording a bit in the KIP to bring
emphasis to this point, although it was mentioned previously. Please refer
to this section: https://cwiki.apache.org/confluence/display/KAFKA/KIP-584

%3A+Versioning+scheme+for+features#KIP-584

:Versioningschemeforfeatures-ChangestoKafkaController.

===

> And now, something a little bit bigger (sorry).  For finalized features,
why do we need both min_version_level and max_version_level?  Assuming that
we want all the
>  brokers to be on the same feature version level, we really only care
about three numbers for each feature, right?  The minimum supported version
level, the maximum
>  supported version level, and the current active version level.

> We don't actually want different brokers to be on different versions of
the same feature, right?  So we can just have one number for current
version level, rather
>  than two.  At least that's what I was thinking -- let me know if I
missed something.

(Kowshik): It is my understanding that the "current active version level"
that you have mentioned, is the "max_version_level". But we still
maintain/publish both min and max version levels, because, the detail about
min level is useful to external clients. This is described below.

For any feature F, think of the closed range: [min_version_level,
max_version_level] as the range of finalized versions, that's guaranteed to
be supported by all brokers in the cluster.
 - "max_version_level" is the finalized highest common version among all
brokers,
 - "min_version_level" is the finalized lowest common version among all
brokers.

Next, think of "client" here as the "user of the 

Re: [VOTE] KIP-584: Versioning scheme for features

[Colin McCabe]

Hi Kowshik,

Thanks again for working on this-- it looks great.  I went over the KIP again 
and have a few more comments.

===

It would be good to note that deprecating a feature version (in other words, 
increasing minVersionLevel on the broker) is an incompatible change, which 
requires a major release of Kafka.  

===

I think the strategy for transitioning from not having a /features znode to 
having one could use some work. The current proposal is to wait for all the 
brokers to fill in their feature znodes and then pick the highest common 
versions.  But that requires blocking in the controller startup code until the 
whole cluster is active (technically, a point in time which we never really 
know that we have reached...)

Instead, I think it would be better to have a strategy like this:
1. If the controller comes up and there is no /features znode AND the IBP is 
less than 2.6, create a /features znode where all the features are disabled.
2. If the controller comes up and there is no /features znode AND the IBP is 
greater than or equal to 2.6, create a /features znode where all the features 
are enabled at the highest versions supported by the controller.

People upgrading from the pre-KIP-584 world will end up in case #1 because they 
have to do a double roll to upgrade, and during the first roll, the IBP is 
unchanged.  People creating new clusters from scratch will end up in case #2, 
which is what we want since we don't want a brand new cluster to be using old 
feature flag versions.

===

UpdateFeaturesResponse#ErrorMessage should specify nullableVersions since null 
is a valid value here

Also, in the message format, the tags we use need to start at 0.

===

I don't think we need the FEATURE_UPDATE_IN_PROGRESS error code.  The 
controller is basically single-threaded and will only do one of these 
operations at once.  Even if it weren't, though, we could simply block the 
second operation behind the first one.

===

For updateFeatures, it would be good to specify that if a single feature 
version update in the batch can't be done, none of them are done.  I think this 
was the intention, but I wasn't able to find it spelled out (maybe i missed it).

===

And now, something a little bit bigger (sorry).  For finalized features, why do 
we need both min_version_level and max_version_level?  Assuming that we want 
all the brokers to be on the same feature version level, we really only care 
about three numbers for each feature, right?  The minimum supported version 
level, the maximum supported version level, and the current active version 
level.

We don't actually want different brokers to be on different versions of the 
same feature, right?  So we can just have one number for current version level, 
rather than two.  At least that's what I was thinking -- let me know if I 
missed something.

best,
Colin


On Tue, Apr 21, 2020, at 13:01, Dhruvil Shah wrote:
> Thanks for the KIP! +1 (non-binding)
> 
> On Tue, Apr 21, 2020 at 6:09 AM David Jacot  wrote:
> 
> > Great KIP, thanks! +1 (non-binding)
> >
> > On Fri, Apr 17, 2020 at 8:56 PM Guozhang Wang  wrote:
> >
> > > Thanks for the great KIP Kowshik, +1 (binding).
> > >
> > > On Fri, Apr 17, 2020 at 11:22 AM Jun Rao  wrote:
> > >
> > > > Hi, Kowshik,
> > > >
> > > > Thanks for the KIP. +1
> > > >
> > > > Jun
> > > >
> > > > On Thu, Apr 16, 2020 at 11:14 AM Kowshik Prakasam <
> > > kpraka...@confluent.io>
> > > > wrote:
> > > >
> > > > > Hi all,
> > > > >
> > > > > I'd like to start a vote for KIP-584. The link to the KIP can be
> > found
> > > > > here:
> > > > >
> > > > >
> > > >
> > >
> > https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features
> > > > > .
> > > > >
> > > > > Thanks!
> > > > >
> > > > >
> > > > > Cheers,
> > > > > Kowshik
> > > > >
> > > >
> > >
> > >
> > > --
> > > -- Guozhang
> > >
> >
>

Re: [VOTE] KIP-584: Versioning scheme for features

[Dhruvil Shah]

Thanks for the KIP! +1 (non-binding)

On Tue, Apr 21, 2020 at 6:09 AM David Jacot  wrote:

> Great KIP, thanks! +1 (non-binding)
>
> On Fri, Apr 17, 2020 at 8:56 PM Guozhang Wang  wrote:
>
> > Thanks for the great KIP Kowshik, +1 (binding).
> >
> > On Fri, Apr 17, 2020 at 11:22 AM Jun Rao  wrote:
> >
> > > Hi, Kowshik,
> > >
> > > Thanks for the KIP. +1
> > >
> > > Jun
> > >
> > > On Thu, Apr 16, 2020 at 11:14 AM Kowshik Prakasam <
> > kpraka...@confluent.io>
> > > wrote:
> > >
> > > > Hi all,
> > > >
> > > > I'd like to start a vote for KIP-584. The link to the KIP can be
> found
> > > > here:
> > > >
> > > >
> > >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features
> > > > .
> > > >
> > > > Thanks!
> > > >
> > > >
> > > > Cheers,
> > > > Kowshik
> > > >
> > >
> >
> >
> > --
> > -- Guozhang
> >
>

Re: [VOTE] KIP-584: Versioning scheme for features

[David Jacot]

Great KIP, thanks! +1 (non-binding)

On Fri, Apr 17, 2020 at 8:56 PM Guozhang Wang  wrote:

> Thanks for the great KIP Kowshik, +1 (binding).
>
> On Fri, Apr 17, 2020 at 11:22 AM Jun Rao  wrote:
>
> > Hi, Kowshik,
> >
> > Thanks for the KIP. +1
> >
> > Jun
> >
> > On Thu, Apr 16, 2020 at 11:14 AM Kowshik Prakasam <
> kpraka...@confluent.io>
> > wrote:
> >
> > > Hi all,
> > >
> > > I'd like to start a vote for KIP-584. The link to the KIP can be found
> > > here:
> > >
> > >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features
> > > .
> > >
> > > Thanks!
> > >
> > >
> > > Cheers,
> > > Kowshik
> > >
> >
>
>
> --
> -- Guozhang
>

Re: [VOTE] KIP-584: Versioning scheme for features

[Guozhang Wang]

Thanks for the great KIP Kowshik, +1 (binding).

On Fri, Apr 17, 2020 at 11:22 AM Jun Rao  wrote:

> Hi, Kowshik,
>
> Thanks for the KIP. +1
>
> Jun
>
> On Thu, Apr 16, 2020 at 11:14 AM Kowshik Prakasam 
> wrote:
>
> > Hi all,
> >
> > I'd like to start a vote for KIP-584. The link to the KIP can be found
> > here:
> >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features
> > .
> >
> > Thanks!
> >
> >
> > Cheers,
> > Kowshik
> >
>


-- 
-- Guozhang

Re: [VOTE] KIP-584: Versioning scheme for features

[Jun Rao]

Hi, Kowshik,

Thanks for the KIP. +1

Jun

On Thu, Apr 16, 2020 at 11:14 AM Kowshik Prakasam 
wrote:

> Hi all,
>
> I'd like to start a vote for KIP-584. The link to the KIP can be found
> here:
>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features
> .
>
> Thanks!
>
>
> Cheers,
> Kowshik
>

Re: [VOTE] KIP-584: Versioning scheme for features

[Boyang Chen]

Thanks Kowshik for driving this effort, I'm +1 (non-binding).

On Thu, Apr 16, 2020 at 11:14 AM Kowshik Prakasam 
wrote:

> Hi all,
>
> I'd like to start a vote for KIP-584. The link to the KIP can be found
> here:
>
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-584%3A+Versioning+scheme+for+features
> .
>
> Thanks!
>
>
> Cheers,
> Kowshik
>