Thanks Edoardo, I've added that motivation to the KIP.
KIP-201 doesn't address two points raised in KIP-170: Adding a validationOnly flag to DeleteTopicRequest and adding an error message to DeleteTopicResponse. Since those are not policy-related I think they're best left out of KIP-201. I suppose it is up to you and Mickael whether to narrow the scope of KIP-170 to address those points. Thanks again, Tom On 4 October 2017 at 08:20, Edoardo Comar <eco...@uk.ibm.com> wrote: > Thanks Tom, > looks got to me and KIP-201 could supersede KIP-170 > but could you please add a missing motivation bullet that was behind > KIP-170: > > introducing ClusterState to allow validation of create/alter topic request > > not just against the request metadata but also > against the current amount of resources already used in the cluster (eg > number of partitions). > > thanks > Edo > -------------------------------------------------- > > Edoardo Comar > > IBM Message Hub > > IBM UK Ltd, Hursley Park, SO21 2JN > > > > From: Tom Bentley <t.j.bent...@gmail.com> > To: dev@kafka.apache.org > Date: 02/10/2017 15:15 > Subject: Re: [DISCUSS] KIP-201: Rationalising Policy interfaces > > > > Hi All, > > I've updated KIP-201 again so there is now a single policy interface (and > thus a single key by which to configure it) for topic creation, > modification, deletion and record deletion, which each have their own > validation method. > > There are still a few loose ends: > > 1. I currently propose validateAlterTopic(), but it would be possible to > be > more fine grained about this: validateAlterConfig(), validAddPartitions() > and validateReassignPartitions(), for example. Obviously this results in a > policy method per operation, and makes it more clear what is being > changed. > I guess the down side is its more work for implementer, and potentially > makes it harder to change the interface in the future. > > 2. A couple of TODOs about what the TopicState interface should return > when > a topic's partitions are being reassigned. > > Your thoughts on these or any other points are welcome. > > Thanks, > > Tom > > On 27 September 2017 at 11:45, Paolo Patierno <ppatie...@live.com> wrote: > > > Hi Ismael, > > > > > > 1. I don't have a real requirement now but "deleting" is an operation > > that could be really dangerous so it's always better having a way for > > having more control on that. I know that we have the authorizer used for > > that (delete on topic) but fine grained control could be better (even > > already happens for topic deletion). > > 2. I know about the problem of restarting broker due to changes on > > policies but what do you mean by doing that on the clients ? > > > > > > Paolo Patierno > > Senior Software Engineer (IoT) @ Red Hat > > Microsoft MVP on Azure & IoT > > Microsoft Azure Advisor > > > > Twitter : @ppatierno< > https://urldefense.proofpoint.com/v2/url?u=http-3A__twitter. > com_ppatierno&d=DwIBaQ&c=jf_iaSHvJObTbx-siA1ZOg&r= > EzRhmSah4IHsUZVekRUIINhltZK7U0OaeRo7hgW4_tQ&m=h-D-nA7uiy1Z-jta5y- > yh7dKgV77XtsUnJ9Rab1gheY&s=43hzTLEDKw2v5Vh0zwkMTaaKD-HdJD8d_F4-Bsw25-Y&e= > > > > Linkedin : paolopatierno< > https://urldefense.proofpoint.com/v2/url?u=http-3A__it. > linkedin.com_in_paolopatierno&d=DwIBaQ&c=jf_iaSHvJObTbx-siA1ZOg&r= > EzRhmSah4IHsUZVekRUIINhltZK7U0OaeRo7hgW4_tQ&m=h-D-nA7uiy1Z-jta5y- > yh7dKgV77XtsUnJ9Rab1gheY&s=Ig0N7Nwf9EHfTJ2pH3jRM1JIdlzXw6R5Drocu0TMRLk&e= > > > > Blog : DevExperience< > https://urldefense.proofpoint.com/v2/url?u=http-3A__ > paolopatierno.wordpress.com_&d=DwIBaQ&c=jf_iaSHvJObTbx-siA1ZOg&r= > EzRhmSah4IHsUZVekRUIINhltZK7U0OaeRo7hgW4_tQ&m=h-D-nA7uiy1Z-jta5y- > yh7dKgV77XtsUnJ9Rab1gheY&s=Tc9NrTtG2GP7-zRjOHkXHfYI0rncO8_jKpedna692z4&e= > > > > > > > > ________________________________ > > From: isma...@gmail.com <isma...@gmail.com> on behalf of Ismael Juma < > > ism...@juma.me.uk> > > Sent: Wednesday, September 27, 2017 10:30 AM > > To: dev@kafka.apache.org > > Subject: Re: [DISCUSS] KIP-201: Rationalising Policy interfaces > > > > A couple of questions: > > > > 1. Is this a concrete requirement from a user or is it hypothetical? > > 2. You sure you would want to do this in the broker instead of the > clients? > > It's worth remembering that updating broker policies involves a rolling > > restart of the cluster, so it's not the right place for things that > change > > frequently. > > > > Ismael > > > > On Wed, Sep 27, 2017 at 11:26 AM, Paolo Patierno <ppatie...@live.com> > > wrote: > > > > > Hi Ismael, > > > > > > regarding motivations for delete records, as I said during the > discussion > > > on KIP-204, it gives the possibility to avoid deleting messages for > > > specific partitions (inside the topic) and starting from a specific > > offset. > > > I could think on some users solutions where they know exactly what the > > > partitions means in a specific topic (because they are using a custom > > > partitioner on the producer side) so they know what kind of messages > are > > > inside a partition allowing to delete them but not the others. In > such a > > > policy a user could also check the timestamp related to the offset for > > > allowing or not deletion on time base. > > > > > > > > > Paolo Patierno > > > Senior Software Engineer (IoT) @ Red Hat > > > Microsoft MVP on Azure & IoT > > > Microsoft Azure Advisor > > > > > > Twitter : @ppatierno< > https://urldefense.proofpoint.com/v2/url?u=http-3A__twitter. > com_ppatierno&d=DwIBaQ&c=jf_iaSHvJObTbx-siA1ZOg&r= > EzRhmSah4IHsUZVekRUIINhltZK7U0OaeRo7hgW4_tQ&m=h-D-nA7uiy1Z-jta5y- > yh7dKgV77XtsUnJ9Rab1gheY&s=43hzTLEDKw2v5Vh0zwkMTaaKD-HdJD8d_F4-Bsw25-Y&e= > > > > > Linkedin : paolopatierno< > https://urldefense.proofpoint.com/v2/url?u=http-3A__it. > linkedin.com_in_paolopatierno&d=DwIBaQ&c=jf_iaSHvJObTbx-siA1ZOg&r= > EzRhmSah4IHsUZVekRUIINhltZK7U0OaeRo7hgW4_tQ&m=h-D-nA7uiy1Z-jta5y- > yh7dKgV77XtsUnJ9Rab1gheY&s=Ig0N7Nwf9EHfTJ2pH3jRM1JIdlzXw6R5Drocu0TMRLk&e= > > > > > Blog : DevExperience< > https://urldefense.proofpoint.com/v2/url?u=http-3A__ > paolopatierno.wordpress.com_&d=DwIBaQ&c=jf_iaSHvJObTbx-siA1ZOg&r= > EzRhmSah4IHsUZVekRUIINhltZK7U0OaeRo7hgW4_tQ&m=h-D-nA7uiy1Z-jta5y- > yh7dKgV77XtsUnJ9Rab1gheY&s=Tc9NrTtG2GP7-zRjOHkXHfYI0rncO8_jKpedna692z4&e= > > > > > > > > > > > ________________________________ > > > From: isma...@gmail.com <isma...@gmail.com> on behalf of Ismael Juma < > > > ism...@juma.me.uk> > > > Sent: Wednesday, September 27, 2017 10:18 AM > > > To: dev@kafka.apache.org > > > Subject: Re: [DISCUSS] KIP-201: Rationalising Policy interfaces > > > > > > A couple more comments: > > > > > > 1. "If this KIP is accepted for Kafka 1.1.0 this removal could happen > in > > > Kafka 1.2.0 or a later release." -> we only remove code in major > > releases. > > > So, if it's deprecated in 1.1.0, it would be removed in 2.0.0. > > > > > > 2. Deleting all messages in a topic is not really the same as deleting > a > > > topic. The latter will cause consumers and producers to error out > while > > the > > > former will not. It would be good to motivate the need for the delete > > > records policy more. > > > > > > Ismael > > > > > > On Wed, Sep 27, 2017 at 11:12 AM, Ismael Juma <ism...@juma.me.uk> > wrote: > > > > > > > Another quick comment: the KIP states that having multiple > interfaces > > > > imply that the logic must be in 2 places. That is not true because > the > > > same > > > > class can implement multiple interfaces (this aspect was considered > > when > > > we > > > > decided to introduce policies incrementally). > > > > > > > > The main reason why I think the original approach doesn't work well > is > > > > that there is no direct mapping between an operation and the policy. > > That > > > > is, we initially thought we would have create/alter/delete topics, > but > > > that > > > > didn't work out as the alter case is better served by multiple > request > > > > types. Given that, it's a bit awkward to maintain the original > approach > > > and > > > > a policy for topic management seemed easier to understand. On that > > note, > > > > would `TopicManagementPolicy` be a better name? > > > > > > > > Looking at the updated KIP, I notice that we actually have a > > > > TopicDeletionPolicy with a separate config. That seems to be a > halfway > > > > house. Not sure about that. > > > > > > > > Ismael > > > > > > > > On Wed, Sep 27, 2017 at 10:47 AM, Tom Bentley > <t.j.bent...@gmail.com> > > > > wrote: > > > > > > > >> I have updated the KIP to add a common policy interface for topic > and > > > >> message deletion. This included pulling ClusterState and TopicState > > > >> interfaces up to the top level so that they can be shared between > the > > > two > > > >> policies. > > > >> > > > >> Cheers, > > > >> > > > >> Tom > > > >> > > > >> On 26 September 2017 at 18:09, Edoardo Comar <eco...@uk.ibm.com> > > wrote: > > > >> > > > >> > Thanks Tom, > > > >> > In my original KIP-170 I mentioned that the method > > > >> > > > > >> > public Map<String, Integer> topicsPartitionCount(); > > > >> > > > > >> > was just a starting point for a general purpose ClusterState > > > >> > as it happened to be exactly the info we needed for our policy > > > >> > implementation :-) > > > >> > it definitely doesn't feel general purpose enough. > > > >> > > > > >> > what about > > > >> > > > > >> > interface ClusterState { > > > >> > public TopicState topicState(String topicName); > > > >> > public Set<String> topics(); > > > >> > } > > > >> > > > > >> > I think that the implementation of ClusterState that the server > will > > > >> pass > > > >> > to the policy.validate method > > > >> > would just lazily tap into MetadataCache. No need for big upfront > > > >> > allocations. > > > >> > > > > >> > ciao, > > > >> > Edo > > > >> > -------------------------------------------------- > > > >> > > > > >> > Edoardo Comar > > > >> > > > > >> > IBM Message Hub > > > >> > > > > >> > IBM UK Ltd, Hursley Park, SO21 2JN > > > >> > > > > >> > > > > >> > > > > >> > From: Tom Bentley <t.j.bent...@gmail.com> > > > >> > To: dev@kafka.apache.org > > > >> > Date: 26/09/2017 17:39 > > > >> > Subject: Re: [DISCUSS] KIP-201: Rationalising Policy > > interfaces > > > >> > > > > >> > > > > >> > > > > >> > Hi Edoardo, > > > >> > > > > >> > > > > >> > what about a single method in ClusterState > > > >> > > > > > >> > > interface ClusterState { > > > >> > > public Map<String,TopicState> topicsState(); > > > >> > > > > > >> > > } > > > >> > > > > > >> > > which could return a read-only snapshot of the cluster metadata > ? > > > >> > > > > > >> > > > > >> > Sure that would work too. A concern with that is that we end up > > > >> allocating > > > >> > a potentially rather large amount for the Map and the collections > > > >> present > > > >> > in the TopicStates in order to provide the snapshot. The caller > > might > > > >> only > > > >> > be interested in one item from the TopicState for one topic in > the > > > map. > > > >> > Accessing this information via methods means the caller only pays > > for > > > >> what > > > >> > they use. > > > >> > > > > >> > Cheers, > > > >> > > > > >> > Tom > > > >> > > > > >> > > > > >> > > > > >> > Unless stated otherwise above: > > > >> > IBM United Kingdom Limited - Registered in England and Wales with > > > number > > > >> > 741598. > > > >> > Registered office: PO Box 41, North Harbour, Portsmouth, > Hampshire > > PO6 > > > >> 3AU > > > >> > > > > >> > > > > > > > > > > > > > > > > > Unless stated otherwise above: > IBM United Kingdom Limited - Registered in England and Wales with number > 741598. > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU >
