Hi Mickael and Viktor,

Recently, I also had research on pluggable logging dependencies. As far as
I experienced in KIP-653, the issues related to the logging dependency are
organized into like the following:

1. Append the desired logging messages.
2. Testing the logging messages. (especially Kafka Streams)
3. Support dynamic logging level change feature in Kafka and Kafka Connect.

As Viktor pointed out, 1 is easy. It seems like 2 is also (relatively)
easy, but the real problem is 3; Presently, we need to use slf4j to make
Kafka and Kafka Connect to be the logging implementation-neutral (like
Kafka Streams currently does). But there is no way to change the logging
level dynamically only with slf4j API yet; All cases I found were making
use of the actual implementation's API, like the following:

-
https://prateep.info/2015/12/12/dynamically-change-log-level-in-slf4j-log4j-with-standalone-java-class/
- https://gist.github.com/nkcoder/cd74919fd80594c56e09b448a2d1ba31

However, this limitation may change in the future - slf4j will support
dynamic logging levels in 2.0:

-
https://stackoverflow.com/questions/2621701/setting-log-level-of-message-at-runtime-in-slf4j
- https://jira.qos.ch/browse/SLF4J-124

So, how about this? *I will keep my eyes on slf4j's update progress, and as
soon as they stabilize their 2.0 implementation, I will file another KIP
for the logger implementation neutrality.* Since there is no precise timing
of slf4j 2.0's stabilization, I think this plan would be more reasonable.

I am looking forward to your valuable opinions.

Thanks,
Dongjin

On Mon, Jan 17, 2022 at 9:28 PM Mickael Maison <mickael.mai...@gmail.com>
wrote:

> Hi Viktor,
>
> a) I think this makes sense. But I think this shouldn't block this
> KIP, it can be done after moving to log4j2.
>
> b) Yes, tests dependencies are for tests only and shouldn't prevent us
> from making other changes.
>
> c) This is what the KIP is now proposing
>
> Thanks,
> Mickael
>
> On Wed, Jan 12, 2022 at 11:37 AM Viktor Somogyi-Vass
> <viktor.somo...@cloudera.com.invalid> wrote:
> >
> > Hi Dongjin,
> >
> > We're also looking into this matter as our stack was also affected by all
> > the log4j hell and users increasingly pushing us to upgrade to log4j2 or
> > logback because of the existing vulnerabilities in log4j1.
> > Regarding the points raised by Haruki:
> >
> > a) In my opinion the best would be to make the dynamic logger support
> > (Log4jController and LoggingResource) pluggable for log4j2 and logback
> (so
> > an interface could be used to define the dynamic logging control methods
> > and a config to specify the implementation). That way we're not bound to
> > either logback or log4j and seems like a low-effort thing to do.
> > Additionally this could be used in Connect too in LoggingResource.
> >
> > b) I think testing dependencies aren't that important from the user
> > perspective, it's fine to either use log4j2 or logback, whichever is
> > easier. Kafka is either used from the distribution (tgz) or pulled in
> > through maven, but test dependencies shouldn't be exposed to the world.
> >
> > c) I would support deprecating the appender in favor of the log4j2 Kafka
> > appender. VerifiableLog4jAppender is intended as a testing tool anyway,
> so
> > I think it's less important to change this to logback.
> >
> > Future vulnerabilities will always be found in either logback or log4j2
> or
> > any other logging framework, so I think the safest approach is to allow
> > users to choose their implementation, while in tests I think we're free
> to
> > use whatever we want as that shouldn't be constrained by vulnerabilities.
> >
> > Viktor
> >
> > On Thu, Dec 23, 2021 at 9:37 AM Haruki Okada <ocadar...@gmail.com>
> wrote:
> >
> > > Thanks for the clarification.
> > >
> > > About 2, I wan't aware of those concerns.
> > > Let me check them first.
> > >
> > >
> > > Thanks,
> > >
> > > 2021年12月23日(木) 13:37 Dongjin Lee <dong...@apache.org>:
> > >
> > > > Hi Haruki,
> > > >
> > > >
> > > > Thanks for organizing the issue.
> > > >
> > > >
> > > > If the community prefers logback, I will gladly change the
> dependency and
> > > > update the PR. However, it has the following issues:
> > > >
> > > >
> > > > 1. The log4j2 vulnerabilities seem mostly fixed, and KIP-653 +
> KIP-719
> > > are
> > > > not released yet. So, using log4j2 (whose recent update pace is so
> high)
> > > > will not affect the users.
> > > >
> > > >
> > > > 2. To switch to logback, the following features should be reworked:
> > > >
> > > >
> > > >   a. Dynamic logger level configuration (core, connect)
> > > >
> > > >   b. Logging tests (streams)
> > > >
> > > >   c. Kafka Appender (tools)
> > > >
> > > >
> > > > a and b are the most challenging ones since there is little
> documentation
> > > > on how to do this, so it requires analyzing the implementation
> itself.
> > > > (what I actually did with log4j2) About c, logback does not provide a
> > > Kafka
> > > > Appender so we have to provide an equivalent.
> > > >
> > > >
> > > > It is why I prefer to use log4j2. How do you think?
> > > >
> > > >
> > > > Thanks,
> > > >
> > > > Dongjin
> > > >
> > > >
> > > > On Thu, Dec 23, 2021 at 9:01 AM Haruki Okada <ocadar...@gmail.com>
> > > wrote:
> > > >
> > > > > Hi, Dongjin,
> > > > >
> > > > > Sorry for interrupting the discussion.
> > > > > And thank you for your hard work about KIP-653, KIP-719.
> > > > >
> > > > > I understand that KIP-653 is already accepted so log4j2 is the
> choice
> > > of
> > > > > the Kafka community though, I'm now feeling that logback is a
> better
> > > > choice
> > > > > here.
> > > > >
> > > > > Reasons:
> > > > >
> > > > > - even after "log4shell", several vulnerabilities found on log4j2
> so
> > > new
> > > > > versions are released and users have to update in high-pace
> > > > >     * actually, a CVE was also reported for logback
> (CVE-2021-42550)
> > > but
> > > > it
> > > > > requires edit-permission of the config file for an attacker so it's
> > > much
> > > > > less threatening
> > > > > - log4j1.x and logback are made by same developer (ceki), so
> > > > substantially
> > > > > the successor of log4j1 is logback rather than log4j2
> > > > > - in Hadoop project, seems similar suggestion was made from a PMC
> > > > >     * https://issues.apache.org/jira/browse/HADOOP-12956
> > > > >
> > > > >
> > > > > What do you think about adopting logback instead?
> > > > >
> > > > >
> > > > > Thanks,
> > > > >
> > > > > 2021年12月21日(火) 18:02 Dongjin Lee <dong...@apache.org>:
> > > > >
> > > > > > Hi Mickael,
> > > > > >
> > > > > > > In the meantime, you may want to bump the VOTE thread too.
> > > > > >
> > > > > > Sure, I just reset the voting thread with a brief context.
> > > > > >
> > > > > > Thanks,
> > > > > > Dongjin
> > > > > >
> > > > > > On Tue, Dec 21, 2021 at 2:13 AM Mickael Maison <
> > > > mickael.mai...@gmail.com
> > > > > >
> > > > > > wrote:
> > > > > >
> > > > > > > Thanks Dongjin!
> > > > > > >
> > > > > > > I'll take a look soon.
> > > > > > > In the meantime, you may want to bump the VOTE thread too.
> > > > > > >
> > > > > > > Best,
> > > > > > > Mickael
> > > > > > >
> > > > > > >
> > > > > > > On Sat, Dec 18, 2021 at 10:00 AM Dongjin Lee <
> dong...@apache.org>
> > > > > wrote:
> > > > > > > >
> > > > > > > > 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>*
> > > > > > >
> > > > > >
> > > > > >
> > > > > > --
> > > > > > *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>*
> > > > > >
> > > > >
> > > > >
> > > > > --
> > > > > ========================
> > > > > Okada Haruki
> > > > > ocadar...@gmail.com
> > > > > ========================
> > > > >
> > > >
> > > >
> > > > --
> > > > *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>*
> > > >
> > >
> > >
> > > --
> > > ========================
> > > Okada Haruki
> > > ocadar...@gmail.com
> > > ========================
> > >
>
>

-- 
*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>*

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