Hi Jun, Just to close the loop on this... the KIP now mentions both ApiVersionResponse and BrokerRegistrationRequest.
best, Colin On Mon, Jul 8, 2024, at 14:57, Jun Rao wrote: > Hi, Colin, > > Thanks for the update. Since the PR also introduces a new version of > BrokerRegistrationRequest, could we include that change in the KIP update > too? > > Jun > > On Mon, Jul 8, 2024 at 11:08 AM Colin McCabe <cmcc...@apache.org> wrote: > >> Hi all, >> >> I've updated the approach in https://github.com/apache/kafka/pull/16421 >> so that we change the minVersion=0 to minVersion=1 in older >> ApiVersionsResponses. >> >> I hope we can get this in soon and unblock the features that are waiting >> for it! >> >> best, >> Colin >> >> On Wed, Jul 3, 2024, at 10:55, Jun Rao wrote: >> > Hi, David, >> > >> > Thanks for the reply. In the common case, there is no difference between >> > omitting just v0 of the feature or omitting the feature completely. It's >> > just when an old client is used, there is some difference. To me, >> > omitting just v0 of the feature seems slightly better for the old client. >> > >> > Jun >> > >> > On Wed, Jul 3, 2024 at 9:45 AM David Jacot <dja...@confluent.io.invalid> >> > wrote: >> > >> >> Hi Jun, Colin, >> >> >> >> Thanks for your replies. >> >> >> >> If the FeatureCommand relies on version 0 too, my suggestion does not >> work. >> >> Omitting the features for old clients as suggested by Colin seems fine >> for >> >> me. In practice, administrators will usually use a version of >> >> FeatureCommand matching the cluster version so the impact is not too bad >> >> knowing that the first features will be introduced from 3.9 on. >> >> >> >> Best, >> >> David >> >> >> >> On Tue, Jul 2, 2024 at 2:15 AM Colin McCabe <cmcc...@apache.org> wrote: >> >> >> >> > Hi David, >> >> > >> >> > In the ApiVersionsResponse, we really don't have an easy way of >> mapping >> >> > finalizedVersion = 1 to "off" in older releases such as 3.7.0. For >> >> example, >> >> > if a 3.9.0 broker advertises that it has finalized group.version = 1, >> >> that >> >> > will be treated by 3.7.0 as a brand new feature, not as "KIP-848 is >> off." >> >> > However, I suppose we could work around this by not setting a >> >> > finalizedVersion at all for group.version (or any other feature) if >> its >> >> > finalized level was 1. We could also work around the "deletion = set >> to >> >> 0" >> >> > issue on the server side. The server can translate requests to set the >> >> > finalized level to 0, into requests to set it to 1. >> >> > >> >> > So maybe this solution is worth considering, although it's >> unfortunate to >> >> > lose 0. I suppose we'd have to special case metadata.version being >> set to >> >> > 1, since that was NOT equivalent to it being "off" >> >> > >> >> > best, >> >> > Colin >> >> > >> >> > >> >> > On Mon, Jul 1, 2024, at 10:11, Jun Rao wrote: >> >> > > Hi, David, >> >> > > >> >> > > Yes, that's another option. It probably has its own challenges. For >> >> > > example, the FeatureCommand tool currently treats disabling a >> feature >> >> as >> >> > > setting the version to 0. It would be useful to get Jose's opinion >> on >> >> > this >> >> > > since he introduced version 0 in the kraft.version feature. >> >> > > >> >> > > Thanks, >> >> > > >> >> > > Jun >> >> > > >> >> > > On Sun, Jun 30, 2024 at 11:48 PM David Jacot >> >> <dja...@confluent.io.invalid >> >> > > >> >> > > wrote: >> >> > > >> >> > >> Hi Jun, Colin, >> >> > >> >> >> > >> Have we considered sticking with the range going from version 1 to >> N >> >> > where >> >> > >> version 1 would be the equivalent of "disabled"? In the >> group.version >> >> > case, >> >> > >> we could introduce group.version=1 that does basically nothing and >> >> > >> group.version=2 that enables the new protocol. I suppose that we >> could >> >> > do >> >> > >> the same for the other features. I agree that it is less elegant >> but >> >> it >> >> > >> would avoid all the backward compatibility issues. >> >> > >> >> >> > >> Best, >> >> > >> David >> >> > >> >> >> > >> On Fri, Jun 28, 2024 at 6:02 PM Jun Rao <j...@confluent.io.invalid> >> >> > wrote: >> >> > >> >> >> > >> > Hi, Colin, >> >> > >> > >> >> > >> > Yes, #3 is the scenario that I was thinking about. >> >> > >> > >> >> > >> > In either approach, there will be some information missing in the >> >> old >> >> > >> > client. It seems that we should just pick the one that's less >> wrong. >> >> > In >> >> > >> the >> >> > >> > more common case when a feature is finalized on the server, >> >> > presenting a >> >> > >> > supported feature with a range of 1-1 seems less wrong than >> omitting >> >> > it >> >> > >> in >> >> > >> > the output of "kafka-features describe". >> >> > >> > >> >> > >> > Thanks, >> >> > >> > >> >> > >> > Jun >> >> > >> > >> >> > >> > On Thu, Jun 27, 2024 at 9:52 PM Colin McCabe <cmcc...@apache.org >> > >> >> > wrote: >> >> > >> > >> >> > >> > > Hi Jun, >> >> > >> > > >> >> > >> > > This is a fair question. I think there's a few different >> scenarios >> >> > to >> >> > >> > > consider: >> >> > >> > > >> >> > >> > > 1. mixed server software versions in a single cluster >> >> > >> > > >> >> > >> > > 2. new client software + old server software >> >> > >> > > >> >> > >> > > 3. old client software + new server software >> >> > >> > > >> >> > >> > > In scenario #1 and #2, we have old (pre-3.9) server software in >> >> the >> >> > >> mix. >> >> > >> > > This old software won't support features like group.version and >> >> > >> > > kraft.version. As we know, there are no features supported in >> 3.8 >> >> > and >> >> > >> > older >> >> > >> > > except metadata.version itself. So the fact that we leave out >> some >> >> > >> stuff >> >> > >> > > from the ApiVersionResponse isn't terribly significant. We >> weren't >> >> > >> going >> >> > >> > to >> >> > >> > > be able to enable those post-3.8 features anyway, since >> enabling a >> >> > >> > feature >> >> > >> > > requires ALL server nodes to support it. >> >> > >> > > >> >> > >> > > Scenario #3 is more interesting. With new server software, >> >> features >> >> > >> like >> >> > >> > > group.version and kraft.version may be enabled. But due to the >> >> > >> > KAFKA-17011 >> >> > >> > > bug, we cannot accurately communicate the supported feature >> range >> >> > back >> >> > >> to >> >> > >> > > the old client. >> >> > >> > > >> >> > >> > > What is the impact of this? It depends on what the client is. >> >> Today, >> >> > >> the >> >> > >> > > only client that cares about feature versions is admin client, >> >> which >> >> > >> can >> >> > >> > > surface them through the Admin.describeFeatures API. So if we >> omit >> >> > the >> >> > >> > > supported feature range, admi client won't report it. If we >> fudge >> >> > it by >> >> > >> > > reporting it as 1-1 instead of 0-1, admin client will report >> the >> >> > fudged >> >> > >> > > version. >> >> > >> > > >> >> > >> > > In theory, there could be other clients looking at the >> supported >> >> > >> feature >> >> > >> > > ranges later, but I guess those will be post-3.8, if they ever >> >> > exist, >> >> > >> and >> >> > >> > > so not subject to this problem. >> >> > >> > > >> >> > >> > > AdminClient returns a separate map for "supported features" and >> >> > >> > "finalized >> >> > >> > > features." So leaving out the supported versions for >> group.version >> >> > and >> >> > >> > > kraft.version will not prevent the client from returning the >> >> > finalized >> >> > >> > > versions of those features to the old client. >> >> > >> > > >> >> > >> > > So basically we have a choice between missing information in >> >> > >> > > Admin.describeFeatures and wrong information. I would lean >> towards >> >> > the >> >> > >> > > missing information path, but I guess we should try out an old >> >> > build of >> >> > >> > > kafka-features.sh against a server with one of the new features >> >> > >> enabled, >> >> > >> > to >> >> > >> > > make sure it looks the way we want. >> >> > >> > > >> >> > >> > > best, >> >> > >> > > Colin >> >> > >> > > >> >> > >> > > >> >> > >> > > On Thu, Jun 27, 2024, at 14:01, Jun Rao wrote: >> >> > >> > > > Hi, Colin, >> >> > >> > > > >> >> > >> > > > ApiVersionResponse includes both supported and finalized >> >> > features. If >> >> > >> > we >> >> > >> > > > only suppress features in the supported field, but not in the >> >> > >> finalized >> >> > >> > > > field, it can potentially lead to inconsistency in the older >> >> > client. >> >> > >> > For >> >> > >> > > > example, if a future feature supporting V0 is finalized in >> the >> >> > >> broker, >> >> > >> > an >> >> > >> > > > old client issuing V3 of ApiVersionRequest will see the >> feature >> >> in >> >> > >> the >> >> > >> > > > finalized field, but not in the supported field. >> >> > >> > > > >> >> > >> > > > An alternative approach is to still include all features in >> the >> >> > >> > supported >> >> > >> > > > field, but replace minVersion of 0 with 1. This may still >> lead >> >> to >> >> > >> > > > inconsistency if a future feature is finalized at version 0. >> >> > However, >> >> > >> > > since >> >> > >> > > > downgrading is less frequent than upgrading, this approach >> seems >> >> > >> > slightly >> >> > >> > > > more consistent. >> >> > >> > > > >> >> > >> > > > No matter what approach we take, it would be useful to >> document >> >> > this >> >> > >> > > > inconsistency to the old client. >> >> > >> > > > >> >> > >> > > > Thanks, >> >> > >> > > > >> >> > >> > > > Jun >> >> > >> > > > >> >> > >> > > > On Wed, Jun 26, 2024 at 1:18 PM Jun Rao <j...@confluent.io> >> >> wrote: >> >> > >> > > > >> >> > >> > > >> Thanks for the reply, Justine and Colin. Sounds good to me. >> >> > >> > > >> >> >> > >> > > >> Jun >> >> > >> > > >> >> >> > >> > > >> On Wed, Jun 26, 2024 at 12:54 PM Colin McCabe < >> >> > cmcc...@apache.org> >> >> > >> > > wrote: >> >> > >> > > >> >> >> > >> > > >>> Hi Justine, >> >> > >> > > >>> >> >> > >> > > >>> Yes, that was what I was thinking. >> >> > >> > > >>> >> >> > >> > > >>> best, >> >> > >> > > >>> Colin >> >> > >> > > >>> >> >> > >> > > >>> On Mon, Jun 24, 2024, at 11:11, Justine Olshan wrote: >> >> > >> > > >>> > My understanding is that the tools that don't rely on >> >> > ApiVersions >> >> > >> > > should >> >> > >> > > >>> > still return 0s when it is the correct value. I believe >> >> these >> >> > >> > > commands >> >> > >> > > >>> do >> >> > >> > > >>> > not require this API and thus can show 0 as versions. >> >> > >> > > >>> > >> >> > >> > > >>> > Likewise, when the old ApiVersionsRequest is used to >> >> describe >> >> > >> > > features, >> >> > >> > > >>> we >> >> > >> > > >>> > can't return 0 versions and we won't be able to see group >> >> > version >> >> > >> > > set. >> >> > >> > > >>> > However, the new api will return 0 and the group version >> >> > >> correctly. >> >> > >> > > >>> > >> >> > >> > > >>> > Let me know if this is consistent with your thoughts, >> Colin. >> >> > >> > > >>> > >> >> > >> > > >>> > Justine >> >> > >> > > >>> > >> >> > >> > > >>> > On Mon, Jun 24, 2024 at 10:44 AM Jun Rao >> >> > >> <j...@confluent.io.invalid >> >> > >> > > >> >> > >> > > >>> wrote: >> >> > >> > > >>> > >> >> > >> > > >>> >> Hi, Colin, >> >> > >> > > >>> >> >> >> > >> > > >>> >> Thanks for the update. The proposed change seems >> reasonable >> >> > to >> >> > >> me. >> >> > >> > > >>> Just one >> >> > >> > > >>> >> clarification. >> >> > >> > > >>> >> >> >> > >> > > >>> >> The KIP can show version 0 of certain features with >> >> > >> > version-mapping >> >> > >> > > >>> >> and feature-dependencies. Will that part change? For >> >> example, >> >> > >> will >> >> > >> > > the >> >> > >> > > >>> tool >> >> > >> > > >>> >> show version 0 features with --release-version 3.8 or >> do we >> >> > >> > exclude >> >> > >> > > >>> them. >> >> > >> > > >>> >> >> >> > >> > > >>> >> bin/kafka-storage.sh version-mapping --release-version >> >> > 3.6-IV1 >> >> > >> > > >>> >> metadata.version=13 (3.6-IV1) transaction.version=0 >> >> > >> > > >>> group.version=0 >> >> > >> > > >>> >> kraft.version=0 >> >> > >> > > >>> >> >> >> > >> > > >>> >> Jun >> >> > >> > > >>> >> >> >> > >> > > >>> >> On Sat, Jun 22, 2024 at 2:19 PM José Armando García >> Sancio >> >> > >> > > >>> >> <jsan...@confluent.io.invalid> wrote: >> >> > >> > > >>> >> >> >> > >> > > >>> >> > Thanks for the update Colin. The changes make sense to >> >> me. >> >> > >> > > >>> >> > >> >> > >> > > >>> >> > Are you planning to update the KIP to reflect this new >> >> RPC >> >> > >> > > version? >> >> > >> > > >>> It >> >> > >> > > >>> >> > would be good to document the semantics explained >> above >> >> in >> >> > the >> >> > >> > > KIP. >> >> > >> > > >>> >> > >> >> > >> > > >>> >> > Thanks! >> >> > >> > > >>> >> > >> >> > >> > > >>> >> > On Fri, Jun 21, 2024 at 8:22 PM Justine Olshan >> >> > >> > > >>> >> > <jols...@confluent.io.invalid> wrote: >> >> > >> > > >>> >> > > >> >> > >> > > >>> >> > > Ok makes sense. I will update my PR. >> >> > >> > > >>> >> > > >> >> > >> > > >>> >> > > On Fri, Jun 21, 2024 at 5:09 PM Colin McCabe < >> >> > >> > > cmcc...@apache.org> >> >> > >> > > >>> >> wrote: >> >> > >> > > >>> >> > > >> >> > >> > > >>> >> > > > I think it's better to suppress the response in >> v3. >> >> The >> >> > >> > issue >> >> > >> > > >>> with >> >> > >> > > >>> >> > > > modifying it is that there may be scenarios where >> [1, >> >> > 1] >> >> > >> is >> >> > >> > > the >> >> > >> > > >>> >> actual >> >> > >> > > >>> >> > > > supported range, and we'd want to know that. But >> >> > leaving >> >> > >> out >> >> > >> > > the >> >> > >> > > >>> >> > feature >> >> > >> > > >>> >> > > > should be OK for older clients (it will be the >> case >> >> > with >> >> > >> > > clients >> >> > >> > > >>> old >> >> > >> > > >>> >> > enough >> >> > >> > > >>> >> > > > to send a v0, v1, or v2 ApiVersionsRequest anyway) >> >> > >> > > >>> >> > > > >> >> > >> > > >>> >> > > > best, >> >> > >> > > >>> >> > > > Colin >> >> > >> > > >>> >> > > > >> >> > >> > > >>> >> > > > On Fri, Jun 21, 2024, at 16:46, Justine Olshan >> wrote: >> >> > >> > > >>> >> > > > > Thanks Colin, >> >> > >> > > >>> >> > > > > >> >> > >> > > >>> >> > > > > This makes sense to me. Namely in the case >> where we >> >> > >> > perhaps >> >> > >> > > >>> don't >> >> > >> > > >>> >> > want to >> >> > >> > > >>> >> > > > > support version 0 anymore, we need the range to >> be >> >> > able >> >> > >> to >> >> > >> > > not >> >> > >> > > >>> >> > include 0. >> >> > >> > > >>> >> > > > > (In other words, we can't assume 0 is supported) >> >> > >> > > >>> >> > > > > It is unfortunate that this change is a bit >> tricky, >> >> > but >> >> > >> I >> >> > >> > > think >> >> > >> > > >>> >> it's >> >> > >> > > >>> >> > the >> >> > >> > > >>> >> > > > > best option. >> >> > >> > > >>> >> > > > > >> >> > >> > > >>> >> > > > > Can you clarify >> >> > >> > > >>> >> > > > >> The server will simply leave out the features >> >> whose >> >> > >> > minimum >> >> > >> > > >>> >> > supported >> >> > >> > > >>> >> > > > > value is 0 for clients that send v3 >> >> > >> > > >>> >> > > > > >> >> > >> > > >>> >> > > > > For 3.8, I planned to set the 0s in the >> response to >> >> > 1. >> >> > >> Is >> >> > >> > it >> >> > >> > > >>> better >> >> > >> > > >>> >> > to >> >> > >> > > >>> >> > > > > suppress the zero version features in the >> response >> >> > so we >> >> > >> > are >> >> > >> > > >>> >> > consistent >> >> > >> > > >>> >> > > > > between trunk and 3.8? >> >> > >> > > >>> >> > > > > >> >> > >> > > >>> >> > > > > Thanks, >> >> > >> > > >>> >> > > > > Justine >> >> > >> > > >>> >> > > > > >> >> > >> > > >>> >> > > > > On Fri, Jun 21, 2024 at 4:34 PM Colin McCabe < >> >> > >> > > >>> cmcc...@apache.org> >> >> > >> > > >>> >> > wrote: >> >> > >> > > >>> >> > > > > >> >> > >> > > >>> >> > > > >> Hi all, >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> It seems that there was a bug in older >> versions of >> >> > >> Kafka >> >> > >> > > which >> >> > >> > > >>> >> > caused >> >> > >> > > >>> >> > > > >> deserialization problems when a supported >> feature >> >> > range >> >> > >> > > >>> included >> >> > >> > > >>> >> 0. >> >> > >> > > >>> >> > For >> >> > >> > > >>> >> > > > >> example, the range for group.version of [0, 1] >> >> would >> >> > >> be a >> >> > >> > > >>> problem >> >> > >> > > >>> >> in >> >> > >> > > >>> >> > > > this >> >> > >> > > >>> >> > > > >> situation. >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> This obviously makes supportedVersions kind of >> >> > useless. >> >> > >> > Any >> >> > >> > > >>> >> feature >> >> > >> > > >>> >> > that >> >> > >> > > >>> >> > > > >> doesn't exist today is effectively at v0 today >> (v0 >> >> > is >> >> > >> > > >>> equivalent >> >> > >> > > >>> >> to >> >> > >> > > >>> >> > > > "off"). >> >> > >> > > >>> >> > > > >> But if we can't declare that the server >> supports >> >> > [0, 1] >> >> > >> > or >> >> > >> > > >>> >> similar, >> >> > >> > > >>> >> > we >> >> > >> > > >>> >> > > > >> can't declare that it supports the feature >> being >> >> > off. >> >> > >> > > >>> Therefore, >> >> > >> > > >>> >> no >> >> > >> > > >>> >> > > > rolling >> >> > >> > > >>> >> > > > >> upgrades are possible. >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> We noticed this bug during the 3.8 release >> when we >> >> > >> > noticed >> >> > >> > > >>> >> problems >> >> > >> > > >>> >> > in >> >> > >> > > >>> >> > > > >> upgrade tests. As an addendum to KIP-1022, >> we're >> >> > adding >> >> > >> > the >> >> > >> > > >>> >> > following >> >> > >> > > >>> >> > > > >> solution: >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> - There will be a new v4 for ApiVersionsRequest >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> - Clients that sent v4 will promise to >> correctly >> >> > handle >> >> > >> > > ranges >> >> > >> > > >>> >> that >> >> > >> > > >>> >> > > > start >> >> > >> > > >>> >> > > > >> with 0, such as [0, 1] >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> - The server will simply leave out the features >> >> > whose >> >> > >> > > minimum >> >> > >> > > >>> >> > supported >> >> > >> > > >>> >> > > > >> value is 0 for clients that send v3 >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> - ApiVersionsRequest v4 will be supported in AK >> >> 3.9 >> >> > and >> >> > >> > > >>> above. AK >> >> > >> > > >>> >> > 3.8 >> >> > >> > > >>> >> > > > will >> >> > >> > > >>> >> > > > >> ship with ApiVersionsRequest v3 just as today. >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> thanks, >> >> > >> > > >>> >> > > > >> Colin >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> On Mon, Apr 15, 2024, at 11:01, Justine Olshan >> >> > wrote: >> >> > >> > > >>> >> > > > >> > Hey folks, >> >> > >> > > >>> >> > > > >> > >> >> > >> > > >>> >> > > > >> > Thanks everyone! I will go ahead and call it. >> >> > >> > > >>> >> > > > >> > The KIP passes with the following +1 votes: >> >> > >> > > >>> >> > > > >> > >> >> > >> > > >>> >> > > > >> > - Andrew Schofield (non-binding) >> >> > >> > > >>> >> > > > >> > - David Jacot (binding) >> >> > >> > > >>> >> > > > >> > - José Armando García Sancio (binding) >> >> > >> > > >>> >> > > > >> > - Jun Rao (binding) >> >> > >> > > >>> >> > > > >> > >> >> > >> > > >>> >> > > > >> > Thanks again, >> >> > >> > > >>> >> > > > >> > Justine >> >> > >> > > >>> >> > > > >> > >> >> > >> > > >>> >> > > > >> > On Fri, Apr 12, 2024 at 11:16 AM Jun Rao >> >> > >> > > >>> >> <j...@confluent.io.invalid >> >> > >> > > >>> >> > > >> >> > >> > > >>> >> > > > >> wrote: >> >> > >> > > >>> >> > > > >> > >> >> > >> > > >>> >> > > > >> >> Hi, Justine, >> >> > >> > > >>> >> > > > >> >> >> >> > >> > > >>> >> > > > >> >> Thanks for the KIP. +1 >> >> > >> > > >>> >> > > > >> >> >> >> > >> > > >>> >> > > > >> >> Jun >> >> > >> > > >>> >> > > > >> >> >> >> > >> > > >>> >> > > > >> >> On Wed, Apr 10, 2024 at 9:13 AM José Armando >> >> > García >> >> > >> > > Sancio >> >> > >> > > >>> >> > > > >> >> <jsan...@confluent.io.invalid> wrote: >> >> > >> > > >>> >> > > > >> >> >> >> > >> > > >>> >> > > > >> >> > Hi Justine, >> >> > >> > > >>> >> > > > >> >> > >> >> > >> > > >>> >> > > > >> >> > +1 (binding) >> >> > >> > > >>> >> > > > >> >> > >> >> > >> > > >>> >> > > > >> >> > Thanks for the improvement. >> >> > >> > > >>> >> > > > >> >> > -- >> >> > >> > > >>> >> > > > >> >> > -José >> >> > >> > > >>> >> > > > >> >> > >> >> > >> > > >>> >> > > > >> >> >> >> > >> > > >>> >> > > > >> >> >> > >> > > >>> >> > > > >> >> > >> > > >>> >> > >> >> > >> > > >>> >> > >> >> > >> > > >>> >> > >> >> > >> > > >>> >> > -- >> >> > >> > > >>> >> > -José >> >> > >> > > >>> >> > >> >> > >> > > >>> >> >> >> > >> > > >>> >> >> > >> > > >> >> >> > >> > > >> >> > >> > >> >> > >> >> >> > >> >> >>
