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From Tom Bentley <t.j.bent...@gmail.com>
Subject Re: [DISCUSS] KIP-201: Rationalising Policy interfaces
Date Wed, 04 Oct 2017 08:20:57 GMT
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 <ECOMAR@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.bentley@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 <ppatierno@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: ismaelj@gmail.com <ismaelj@gmail.com> on behalf of Ismael Juma <
> > ismael@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 <ppatierno@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: ismaelj@gmail.com <ismaelj@gmail.com> on behalf of Ismael Juma
<
> > > ismael@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 <ismael@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.bentley@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 <ECOMAR@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.bentley@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
>

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