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<http://twitter.com/ppatierno> > Linkedin : paolopatierno<http://it.linkedin.com/in/paolopatierno> > Blog : DevExperience<http://paolopatierno.wordpress.com/> > > > ________________________________ > 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<http://twitter.com/ppatierno> > > Linkedin : paolopatierno<http://it.linkedin.com/in/paolopatierno> > > Blog : DevExperience<http://paolopatierno.wordpress.com/> > > > > > > ________________________________ > > 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 > > >> > > > >> > > > > > > > > >
