Hi Mickael, Finally, I did it! As you can see at the PR <https://github.com/apache/kafka/pull/10244>, KIP-719 now uses log4j2's Kafka appender, and log4j-appender is not used by the other modules anymore. You can see how it will work with KIP-653 at this preview <http://home.apache.org/~dongjin/post/apache-kafka-log4j2-support/>, based on Apache Kafka 3.0.0. The proposal document <https://cwiki.apache.org/confluence/display/KAFKA/KIP-719%3A+Deprecate+Log4J+Appender> is also updated accordingly, with its title.
There is a minor issue on log4j2 <https://issues.apache.org/jira/browse/LOG4J2-3256>, but it seems like it will be resolved soon. Best, Dongjin On Wed, Dec 15, 2021 at 9:28 PM Dongjin Lee <dong...@apache.org> wrote: > Hi Mickael, > > > Can we do step 3 without breaking any compatibility? If so then that > sounds like a good idea. > > As far as I know, the answer is yes; I am now updating my PR, so I will > notify you as soon as I complete the work. > > Best, > Dongjin > > On Wed, Dec 15, 2021 at 2:00 AM Mickael Maison <mickael.mai...@gmail.com> > wrote: > >> Hi Dongjin, >> >> Sorry for the late reply. Can we do step 3 without breaking any >> compatibility? If so then that sounds like a good idea. >> >> Thanks, >> Mickael >> >> >> >> On Tue, Nov 23, 2021 at 2:08 PM Dongjin Lee <dong...@apache.org> wrote: >> > >> > Hi Mickael, >> > >> > I also thought over the issue thoroughly and would like to propose a >> minor >> > change to your proposal: >> > >> > 1. Deprecate log4j-appender now >> > 2. Document how to migrate into logging-log4j2 >> > 3. (Changed) Replace the log4j-appender (in turn log4j 1.x) >> dependencies in >> > tools, trogdor, and shell and upgrade to log4j2 in 3.x, removing log4j >> 1.x >> > dependencies. >> > 4. (Changed) Remove log4j-appender in Kafka 4.0 >> > >> > What we need to do for the log4j2 upgrade is just removing the log4j >> > dependencies only, for they can cause a classpath error. And actually, >> we >> > can do it without discontinuing publishing the log4j-appender artifact. >> So, >> > I suggest separating the upgrade to log4j2 and removing the >> log4j-appender >> > module. >> > >> > How do you think? If you agree, I will update the KIP and the PR >> > accordingly ASAP. >> > >> > Thanks, >> > Dongjin >> > >> > On Mon, Nov 15, 2021 at 8:06 PM Mickael Maison < >> mickael.mai...@gmail.com> >> > wrote: >> > >> > > Hi Dongjin, >> > > >> > > Thanks for the clarifications. >> > > >> > > I wonder if a simpler course of action could be: >> > > - Deprecate log4j-appender now >> > > - Document how to use logging-log4j2 >> > > - Remove log4j-appender and all the log4j dependencies in Kafka 4.0 >> > > >> > > This delays KIP-653 till Kafka 4.0 but (so far) Kafka is not directly >> > > affected by the log4j CVEs. At least this gives us a clear and simple >> > > roadmap to follow. >> > > >> > > What do you think? >> > > >> > > On Tue, Nov 9, 2021 at 12:12 PM Dongjin Lee <dong...@apache.org> >> wrote: >> > > > >> > > > Hi Mickael, >> > > > >> > > > I greatly appreciate you for reading the proposal so carefully! I >> wrote >> > > it >> > > > quite a while ago and rechecked it today. >> > > > >> > > > > Is the KIP proposing to replace the existing log4-appender or >> simply >> > > add >> > > > a new one for log4j2? Reading the KIP and with its current title, >> it's >> > > not >> > > > entirely explicit. >> > > > >> > > > Oh, After re-reading it, I realized that this is not clear. Let me >> > > clarify; >> > > > >> > > > 1. Provide a lo4j2 equivalent of traditional log4j-appender, >> > > > log4j2-appender. >> > > > 2. Migrate the modules depending on log4j-appender (i.e., tools, >> trogdor, >> > > > shell) into log4j2-appender, removing log4j-appender from >> dependencies. >> > > > 3. Entirely remove log4j-appender from the project dependencies, >> along >> > > with >> > > > log4j. >> > > > >> > > > I think log4j-appender may be published for every new release like >> > > before, >> > > > but the committee should make a decision on the policy. >> > > > >> > > > > Under Rejected Alternative, the KIP states: "the Kafka appender >> > > provided >> > > > by log4j2 community stores log message in the Record key". Looking >> at the >> > > > code, it looks like the log message is stored in the Record value: >> > > > >> > > >> https://github.com/apache/logging-log4j2/blob/master/log4j-kafka/src/main/java/org/apache/logging/log4j/kafka/appender/KafkaManager.java#L135 >> > > > Am I missing something? >> > > > >> > > > It's totally my fault; I confused it with another appender. The >> > > > compatibility problem in the logging-log4j2 Kafka appender is not >> the >> > > > format but the configuration. logging-log4j2 Kafka appender supports >> > > > `properties` configuration, which will be directly used to >> instantiate a >> > > > Kafka producer. However, log4j-appender has been using non-producer >> > > config >> > > > names like brokerList (=bootstrap.servers), requiredNumAcks (=acks). >> > > > Instead, logging-log4j2 Kafka appender supports retryCount, >> > > > sendEventTimestamp. >> > > > >> > > > On second thought, using logging-log4j2 Kafka appender internally >> and >> > > > making log4j2-appender to focus on compatibility facade only would >> be a >> > > > better approach; As I described above, the goal of this module is >> just >> > > > keeping the backward-compatibility, and (as you pointed out) the >> current >> > > > implementation has little value. Since >> > > org.apache.logging.log4j:log4j-core >> > > > already includes Kafka appender, we can make use of the 'proven >> wheel' >> > > > without adding more dependencies. I have not tried it yet, but I >> think it >> > > > is well worth it. (One additional advantage of this approach is >> > > providing a >> > > > bridge to the users who hope to move from/into logging-log4j2 Kafka >> > > > appender.) >> > > > >> > > > > As the current log4j-appender is not even deprecated yet, in >> theory we >> > > > can't remove it till Kafka 4. If we want to speed up the process, I >> > > wonder >> > > > if the lack of documentation and a migration guide could help us. >> What do >> > > > you think? >> > > > >> > > > In fact, this is what I am doing nowadays. While working with >> > > > log4j-appender, I found that despite a lack of documentation, >> > > considerable >> > > > users are already using it[^1][^2][^3][^4][^5]. So, I think >> providing a >> > > > documentation to those who are already using log4j-appender is >> > > > indispensable. It should include: >> > > > >> > > > - What is the difference between log4j-appender vs. log4j2-appender. >> > > > - Which options are supported and deprecated. >> > > > - Exemplar configurations that show how to migrate. >> > > > >> > > > Here is the summary: >> > > > >> > > > 1. The goal of this proposal is to replace the traditional >> log4j-appender >> > > > for compatibility concerns. But log4j-appender may be published >> after the >> > > > deprecation. >> > > > 2. As of present, the description about logging-log4j2 Kafka >> appender is >> > > > entirely wrong. The problem is interface compatibility, not record >> > > format. >> > > > Focusing on the compatibility facade is a good approach. >> > > > 3. A documentation focus on migration should be provided. >> > > > >> > > > If you have any questions or suggestions, don't hesitate to tell me. >> > > Thanks >> > > > again for your comments! >> > > > >> > > > Best, >> > > > Dongjin >> > > > >> > > > [^1]: >> > > > >> > > >> https://docs.cloudera.com/csa/1.2.0/monitoring/topics/csa-kafka-logging.html >> > > > [^2]: >> > > > >> > > >> https://stackoverflow.com/questions/22034895/how-to-use-kafka-0-8-log4j-appender >> > > > [^3]: >> > > > >> > > >> https://stackoverflow.com/questions/32402405/delay-in-kafka-log4j-appender >> > > > [^4]: >> > > > >> > > >> https://stackoverflow.com/questions/32301129/kafka-log4j-appender-not-sending-messages >> > > > [^5]: >> > > > >> > > >> https://stackoverflow.com/questions/35628706/kafka-log4j-appender-0-9-does-not-work >> > > > >> > > > On Mon, Nov 8, 2021 at 9:04 PM Mickael Maison < >> mickael.mai...@gmail.com> >> > > > wrote: >> > > > >> > > > > Hi Dongjin, >> > > > > >> > > > > Thanks for working on the update to log4j2, it's definitively >> > > > > something we should complete. >> > > > > I have a couple of comments: >> > > > > >> > > > > 1) Is the KIP proposing to replace the existing log4-appender or >> > > > > simply add a new one for log4j2? Reading the KIP and with its >> current >> > > > > title, it's not entirely explicit. For example I don't see a >> statement >> > > > > under the proposed changes section. The PR seems to only add a new >> > > > > appender but the KIP mentions we want to fully remove >> dependencies to >> > > > > log4j. >> > > > > >> > > > > 2) Under Rejected Alternative, the KIP states: "the Kafka appender >> > > > > provided by log4j2 community stores log message in the Record >> key". >> > > > > Looking at the code, it looks like the log message is stored in >> the >> > > > > Record value: >> > > > > >> > > >> https://github.com/apache/logging-log4j2/blob/master/log4j-kafka/src/main/java/org/apache/logging/log4j/kafka/appender/KafkaManager.java#L135 >> > > > > Am I missing something? >> > > > > Comparing it with the proposed new appender, apart from their >> > > > > configuration format (hence the backwards compatibility issues), >> they >> > > > > both work pretty much the same way, so it's not clear it would >> add a >> > > > > ton a value. >> > > > > >> > > > > At a glance, _I've not extensively looked at it_, it does not look >> > > > > very hard to migrate to the appender from the logging team. I was >> > > > > wondering if we should mention it in our documentation but I was >> not >> > > > > able to find any references to the log4j-appender in the Kafka >> docs: >> > > > > https://github.com/apache/kafka-site/search?q=KafkaLog4jAppender >> > > > > >> > > > > As the current log4j-appender is not even deprecated yet, in >> theory we >> > > > > can't remove it till Kafka 4. If we want to speed up the process, >> I >> > > > > wonder if the lack of documentation and a migration guide could >> help >> > > > > us. What do you think? >> > > > > >> > > > > Thanks, >> > > > > Mickael >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > On Fri, Jun 11, 2021 at 4:57 PM Boojapho O <booja...@gmail.com> >> wrote: >> > > > > > >> > > > > > Continuing to use log4j would leave several known security >> > > > > vulnerabilities in Apache Kafka, including >> > > > > https://nvd.nist.gov/vuln/detail/CVE-2019-17571. The Apache >> log4j >> > > team >> > > > > will not fix this vulnerability and is urging an upgrade to >> log4j2. >> > > See >> > > > > https://logging.apache.org/log4j/1.2/ for further information. >> > > > > > >> > > > > > This is desperately needed in Apache 3.0 to keep the software >> secure. >> > > > > > >> > > > > > On 2021/05/26 12:31:20, Dongjin Lee <dong...@apache.org> wrote: >> > > > > > > CC'd the +1ers of KIP-653 with detailed context: >> > > > > > > >> > > > > > > When I submitted and got the approval of KIP-653: Upgrade >> log4j to >> > > > > log4j2 >> > > > > > > < >> > > > > >> > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-653%3A+Upgrade+log4j+to+log4j2 >> > > > > >, >> > > > > > > I thought the log4j2-appender should not be the scope of the >> work. >> > > But >> > > > > it >> > > > > > > was wrong. >> > > > > > > >> > > > > > > Since the VerifiableLog4jAppender tool is built upon >> > > log4j-appender, >> > > > > log4j >> > > > > > > 1.x artifact will co-exist with log4j2 artifact in the >> classpath >> > > within >> > > > > > > this scheme. Since the log4j 1.x code is not called anymore, I >> > > thought >> > > > > it >> > > > > > > is not problematic but actually, it was not - when I started >> to >> > > > > provide a >> > > > > > > preview of KIP-653 >> > > > > > > < >> http://home.apache.org/~dongjin/post/apache-kafka-log4j2-support/ >> > > >, >> > > > > some >> > > > > > > users reported that sometimes slf4j fails to find the >> appropriate >> > > > > binding >> > > > > > > within the classpath, resulting fail to append the log >> message. >> > > > > > > >> > > > > > > To resolve this problem, I subtly adjusted the scope of the >> work; I >> > > > > > > excluded Tools and Trogdor from KIP-653 and extended KIP-719 >> to >> > > take >> > > > > care >> > > > > > > of them instead, along with providing log4j2-appender. It is >> why >> > > the >> > > > > > > current WIP implementations include some classpath logic in >> the >> > > shell >> > > > > > > script and *why KIP-653 only can't complete the log4j2 >> migration*. >> > > > > > > >> > > > > > > I hope you will check this proposal out. >> > > > > > > >> > > > > > > Best, >> > > > > > > Dongjin >> > > > > > > >> > > > > > > On Tue, May 25, 2021 at 10:43 PM Dongjin Lee < >> dong...@apache.org> >> > > > > wrote: >> > > > > > > >> > > > > > > > Bumping up the discussion thread. >> > > > > > > > >> > > > > > > > Recently, I updated the document of KIP-653: Upgrade log4j >> to >> > > log4j2 >> > > > > > > > < >> > > > > >> > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-653%3A+Upgrade+log4j+to+log4j2 >> > > > >> > > > > (accepted) >> > > > > > > > and KIP-719: Add Log4J2 Appender >> > > > > > > > < >> > > > > >> > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-719%3A+Add+Log4J2+Appender >> > > > >> > > > > (under >> > > > > > > > discussion) reflecting the recent changes to our codebase. >> > > > > Especially: >> > > > > > > > >> > > > > > > > 1. KIP-653 document >> > > > > > > > < >> > > > > >> > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-653%3A+Upgrade+log4j+to+log4j2 >> > > > >> > > > > now >> > > > > > > > explains which modules will be migrated and why. >> > > > > > > > 2. KIP-719 document >> > > > > > > > < >> > > > > >> > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-719%3A+Add+Log4J2+Appender >> > > > >> > > > > now >> > > > > > > > explains not only the log4j2-appender plan but also >> upgrading the >> > > > > omitted >> > > > > > > > modules in KIP-653 into log4j2. >> > > > > > > > >> > > > > > > > As you can see here, those two KIPs are the different parts >> of >> > > the >> > > > > same >> > > > > > > > problem. I believe the community will have a good grasp on >> why >> > > both >> > > > > KIPs >> > > > > > > > are best if released altogether. >> > > > > > > > >> > > > > > > > I will open the voting thread now, and please leave a vote >> if >> > > you are >> > > > > > > > interested in this issue. >> > > > > > > > >> > > > > > > > Best, >> > > > > > > > Dongjin >> > > > > > > > >> > > > > > > > On Tue, Mar 2, 2021 at 5:00 PM Dongjin Lee < >> dong...@apache.org> >> > > > > wrote: >> > > > > > > > >> > > > > > > >> Hi Kafka dev, >> > > > > > > >> >> > > > > > > >> I would like to start the discussion of KIP-719: Add Log4J2 >> > > > > Appender. >> > > > > > > >> >> > > > > > > >> >> > > > > > > >> >> > > > > >> > > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-719%3A+Add+Log4J2+Appender >> > > > > > > >> >> > > > > > > >> All kinds of feedbacks are greatly appreciated! >> > > > > > > >> >> > > > > > > >> Best, >> > > > > > > >> Dongjin >> > > > > > > >> >> > > > > > > >> -- >> > > > > > > >> *Dongjin Lee* >> > > > > > > >> >> > > > > > > >> *A hitchhiker in the mathematical world.* >> > > > > > > >> >> > > > > > > >> >> > > > > > > >> >> > > > > > > >> *github: <http://goog_969573159/>github.com/dongjinleekr >> > > > > > > >> <https://github.com/dongjinleekr>keybase: >> > > > > https://keybase.io/dongjinleekr >> > > > > > > >> <https://keybase.io/dongjinleekr>linkedin: >> > > > > kr.linkedin.com/in/dongjinleekr >> > > > > > > >> <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: >> > > > > speakerdeck.com/dongjin >> > > > > > > >> <https://speakerdeck.com/dongjin>* >> > > > > > > >> >> > > > > > > > >> > > > > > > > >> > > > > > > > -- >> > > > > > > > *Dongjin Lee* >> > > > > > > > >> > > > > > > > *A hitchhiker in the mathematical world.* >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > *github: <http://goog_969573159/>github.com/dongjinleekr >> > > > > > > > <https://github.com/dongjinleekr>keybase: >> > > > > https://keybase.io/dongjinleekr >> > > > > > > > <https://keybase.io/dongjinleekr>linkedin: >> > > > > kr.linkedin.com/in/dongjinleekr >> > > > > > > > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: >> > > > > speakerdeck.com/dongjin >> > > > > > > > <https://speakerdeck.com/dongjin>* >> > > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > -- >> > > > > > > *Dongjin Lee* >> > > > > > > >> > > > > > > *A hitchhiker in the mathematical world.* >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > *github: <http://goog_969573159/>github.com/dongjinleekr >> > > > > > > <https://github.com/dongjinleekr>keybase: >> > > > > https://keybase.io/dongjinleekr >> > > > > > > <https://keybase.io/dongjinleekr>linkedin: >> > > > > kr.linkedin.com/in/dongjinleekr >> > > > > > > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: >> > > > > speakerdeck.com/dongjin >> > > > > > > <https://speakerdeck.com/dongjin>* >> > > > > > > >> > > > > >> > > > >> > > > >> > > > -- >> > > > *Dongjin Lee* >> > > > >> > > > *A hitchhiker in the mathematical world.* >> > > > >> > > > >> > > > >> > > > *github: <http://goog_969573159/>github.com/dongjinleekr >> > > > <https://github.com/dongjinleekr>keybase: >> > > https://keybase.io/dongjinleekr >> > > > <https://keybase.io/dongjinleekr>linkedin: >> > > kr.linkedin.com/in/dongjinleekr >> > > > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: >> > > speakerdeck.com/dongjin >> > > > <https://speakerdeck.com/dongjin>* >> > > >> > >> > >> > -- >> > *Dongjin Lee* >> > >> > *A hitchhiker in the mathematical world.* >> > >> > >> > >> > *github: <http://goog_969573159/>github.com/dongjinleekr >> > <https://github.com/dongjinleekr>keybase: >> https://keybase.io/dongjinleekr >> > <https://keybase.io/dongjinleekr>linkedin: >> kr.linkedin.com/in/dongjinleekr >> > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: >> speakerdeck.com/dongjin >> > <https://speakerdeck.com/dongjin>* >> > > > -- > *Dongjin Lee* > > *A hitchhiker in the mathematical world.* > > > > *github: <http://goog_969573159/>github.com/dongjinleekr > <https://github.com/dongjinleekr>keybase: https://keybase.io/dongjinleekr > <https://keybase.io/dongjinleekr>linkedin: kr.linkedin.com/in/dongjinleekr > <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: speakerdeck.com/dongjin > <https://speakerdeck.com/dongjin>* > -- *Dongjin Lee* *A hitchhiker in the mathematical world.* *github: <http://goog_969573159/>github.com/dongjinleekr <https://github.com/dongjinleekr>keybase: https://keybase.io/dongjinleekr <https://keybase.io/dongjinleekr>linkedin: kr.linkedin.com/in/dongjinleekr <https://kr.linkedin.com/in/dongjinleekr>speakerdeck: speakerdeck.com/dongjin <https://speakerdeck.com/dongjin>*
