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 >> > >> > > >>> >> > >> > >> > > >>> >> >> > >> > > >>> >> > >> > > >> >> > >> > > >> > >> > >> > >> >> > >>
