I'm definitely in favor of having such hooks in the produce/consume life-cycle. Not sure if people remember this but in Kafka 0.7 this was pretty much how it was: https://github.com/apache/kafka/blob/0.7/core/src/main/scala/kafka/producer/async/CallbackHandler.scala i.e., we had something similar to the interceptor proposal for various stages of the producer request. The producer provided call-backs for beforeEnqueue, afterEnqueue, afterDequeuing, beforeSending, etc. So at LinkedIn we in fact did auditing within these call-backs (and not explicitly in the wrapper). Over time and with 0.8 we moved that out to the wrapper libraries.
On a side-note while audit and other monitoring can be done internally in a convenient way I think it should be clarified that having a wrapper is in general not a bad idea and I would even consider it to be a best-practice. Even with 0.7 we still had a wrapper library and that API has largely stayed the same and has helped protect against (sometimes backwards incompatible) changes in open source. While we are on this topic I have one comment and Anna, you may have already considered this but I don't see mention of it in the KIP: Add a custom message interceptor/validator on the broker on message arrival. We decompress and do basic validation of messages on arrival. I think there is value in supporting custom validation and expand it to support custom on-arrival processing. Here is a specific use-case I have in mind. The blog that James referenced describes our auditing infrastructure. In order to audit the Kafka cluster itself we need to run a "console auditor" service that consumes everything and spits out audit events back to the cluster. I would prefer not having to run this service because: - Well, it is one more service that we have to run and monitor - Consuming everything takes up bandwidth which can be avoided - The console auditor consumer itself can lag and cause temporary audit discrepancies One way we can mitigate this is by having mirror-makers in between clusters emit audit events. The problem is that the very last cluster in the pipeline will not have any audit which is why we need to have something to audit the cluster. If we had a custom message validator then the audit can be done on-arrival and we won't need a console auditor. One potential issue in this approach and any elaborate on-arrival processing for that matter is that you may need to deserialize the message as well which can drive up produce request handling times. However I'm not terribly concerned about that especially if the audit header can be separated out easily or even deserialized partially as this Avro thread touches on http://search-hadoop.com/m/F2svI1HDLY12W8tnH1&subj=Re+any+optimization+in+reading+a+partial+schema+in+the+decoder+ Thanks, Joel On Mon, Jan 25, 2016 at 12:02 PM, Mayuresh Gharat < gharatmayures...@gmail.com> wrote: > Nice KIP. Excellent idea. > Was just thinking if we can add onDequed() to the ProducerIterceptor > interface. Since we have the onEnqueued(), it will help the client or the > tools to know how much time the message spent in the RecordAccumulator. > Also an API to check if there are any messages left for a particular topic > in the RecordAccumulator would help. > > Thanks, > > Mayuresh > > On Mon, Jan 25, 2016 at 11:29 AM, Todd Palino <tpal...@gmail.com> wrote: > > > Great idea. I’ve been talking about this for 2 years, and I’m glad > someone > > is finally picking it up. Will take a look at the KIP at some point > > shortly. > > > > -Todd > > > > > > On Mon, Jan 25, 2016 at 11:24 AM, Jay Kreps <j...@confluent.io> wrote: > > > > > Hey Becket, > > > > > > Yeah this is really similar to the callback. The difference is really > in > > > who sets the behavior. The idea of the interceptor is that it doesn't > > > require any code change in apps so you can globally add behavior to > your > > > Kafka usage without changing app code. Whereas the callback is added by > > the > > > app. The idea is to kind of obviate the need for the wrapper code that > > e.g. > > > LinkedIn maintains to hold this kind of stuff. > > > > > > -Jay > > > > > > On Sun, Jan 24, 2016 at 4:21 PM, Becket Qin <becket....@gmail.com> > > wrote: > > > > > > > This could be a useful feature. And I think there are some use cases > to > > > > mutate the data like rejected alternative one mentioned. > > > > > > > > I am wondering if there is functional overlapping between > > > > ProducerInterceptor.onAcknowledgement() and the producer callback? I > > can > > > > see that the Callback could be a per record setting while > > > > onAcknowledgement() is a producer level setting. Other than that, is > > > there > > > > any difference between them? > > > > > > > > Thanks, > > > > > > > > Jiangjie (Becket) Qin > > > > > > > > On Fri, Jan 22, 2016 at 6:21 PM, Neha Narkhede <n...@confluent.io> > > > wrote: > > > > > > > > > James, > > > > > > > > > > That is one of the many monitoring use cases for the interceptor > > > > interface. > > > > > > > > > > Thanks, > > > > > Neha > > > > > > > > > > On Fri, Jan 22, 2016 at 6:18 PM, James Cheng <jch...@tivo.com> > > wrote: > > > > > > > > > > > Anna, > > > > > > > > > > > > I'm trying to understand a concrete use case. It sounds like > > producer > > > > > > interceptors could be used to implement part of LinkedIn's Kafak > > > Audit > > > > > > tool? https://engineering.linkedin.com/kafka/running-kafka-scale > > > > > > > > > > > > Part of that is done by a wrapper library around the kafka > producer > > > > that > > > > > > keeps a count of the number of messages produced, and then sends > > that > > > > > count > > > > > > to a side-topic. It sounds like the producer interceptors could > > > > possibly > > > > > be > > > > > > used to implement that? > > > > > > > > > > > > -James > > > > > > > > > > > > > On Jan 22, 2016, at 4:33 PM, Anna Povzner <a...@confluent.io> > > > wrote: > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > I just created a KIP-42 for adding producer and consumer > > > interceptors > > > > > for > > > > > > > intercepting messages at different points on producer and > > consumer. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-42%3A+Add+Producer+and+Consumer+Interceptors > > > > > > > > > > > > > > Comments and suggestions are welcome! > > > > > > > > > > > > > > Thanks, > > > > > > > Anna > > > > > > > > > > > > > > > > > > ________________________________ > > > > > > > > > > > > This email and any attachments may contain confidential and > > > privileged > > > > > > material for the sole use of the intended recipient. Any review, > > > > copying, > > > > > > or distribution of this email (or any attachments) by others is > > > > > prohibited. > > > > > > If you are not the intended recipient, please contact the sender > > > > > > immediately and permanently delete this email and any > attachments. > > No > > > > > > employee or agent of TiVo Inc. is authorized to conclude any > > binding > > > > > > agreement on behalf of TiVo Inc. by email. Binding agreements > with > > > TiVo > > > > > > Inc. may only be made by a signed written agreement. > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > Thanks, > > > > > Neha > > > > > > > > > > > > > > > > > > > > -- > > *—-* > > *Todd Palino* > > Staff Site Reliability Engineer > > Data Infrastructure Streaming > > > > > > > > linkedin.com/in/toddpalino > > > > > > -- > -Regards, > Mayuresh R. Gharat > (862) 250-7125 >
