Re: Review Request 30403: Patch for KAFKA-1906

[Jeff Holoman <jh...@cloudera.com>]

Yep I totally get that. But...you already have to modify the configs
anyway. The primary goals of default values are basically two-fold

1) Get started quickly
2) Provide reasonable values for stuff people don't really know about.

I guess I would just rather see people take the time (30s to 1min maybe?)
to consider where they want their storage location for Kafka to be. I don't
think that's an unreasonable expectation and will save people like me from
having to help people move stuff when they realize "/" has filled up.

At any rate, I think what's been suggested here is better than /tmp

Thanks

Jeff

On Sat, Jan 31, 2015 at 10:27 AM, Jaikiran Pai <ja...@gmail.com>
wrote:

>  Hi Jeff,
>
> I guess you are :)
>
> Personally, whenever I download and try a new project *in development
> environment* I always just want to get it up and running without having to
> fiddle with configurations. Of course, I do a bit of reading the docs,
> before trying it out, but I like to have the install and run to be
> straightforward without having to change/add configurations. Having
> sensible defaults helps in development environments and in getting started.
> IMO, this param belongs to that category.
>
> -Jaikiran
>
>
> On Thursday 29 January 2015 08:00 PM, Jeff Holoman wrote:
>
> Maybe I'm in the minority here, but I actually don't think there should be
> a default for this param and you should be required to explicitly set this.
>
> On Thu, Jan 29, 2015 at 5:43 AM, Jay Kreps <bo...@gmail.com> wrote:
>
>>
>>
>> > On Jan. 29, 2015, 6:50 a.m., Gwen Shapira wrote:
>> > > We added --override option to KafkaServer that allows overriding
>> default configuration from commandline.
>> > > I believe that just changing the shell script to include --override
>> log.dir=${KAFKA_HOME}/data
>> > > may be enough?
>> > >
>> > > overriding configuration from server.properties in code can be very
>> unintuitive.
>> >
>> > Jaikiran Pai wrote:
>> >     That sounds a good idea. I wasn't aware of the --override option.
>> I'll give that a try and if it works then the change will be limited to
>> just the scripts.
>> >
>> > Jaikiran Pai wrote:
>> >     Hi Gwen,
>> >
>> >     I had a look at the JIRA
>> https://issues.apache.org/jira/browse/KAFKA-1654 which added support for
>> --override and also the purpose of that option. From what I see it won't be
>> useful in this case, because in this current task, we don't want to
>> override a value that has been explicitly set (via server.properties for
>> example). Instead we want to handle a case where no explicit value is
>> specified for the data log directory and in such cases default it to a path
>> which resides under the Kafka install directory.
>> >
>> >     If we use the --override option in our (startup) scripts to set
>> log.dir=${KAFKA_HOME}/data, we will end up forcing this value as the
>> log.dir even when the user has intentionally specified a different path for
>> the data logs.
>> >
>> >     Let me know if I misunderstood your suggestion.
>> >
>> > Jay Kreps wrote:
>> >     I think you are right that --override won't work but maybe this is
>> still a good suggestion?
>> >
>> >     Something seems odd about force overriding the working directory of
>> the process just to set the log directory.
>> >
>> >     Another option might be to add --default. This would work like
>> --override but would provide a default value only if none is specified. I
>> think this might be possible because the java.util.Properties we use for
>> config supports a hierarchy of defaults. E.g. you can say new
>> Properties(defaultProperties). Not sure if this is better or worse.
>> >
>> >     Thoughts?
>> >
>> > Jaikiran Pai wrote:
>> >     Hi Jay,
>> >
>> >     > Another option might be to add --default. This would work like
>> --override but would provide a default value only if none is specified. I
>> think this might be possible because the java.util.Properties we use for
>> config supports a hierarchy of defaults. E.g. you can say new
>> Properties(defaultProperties). Not sure if this is better or worse.
>> >
>> >     I think --default sounds like a good idea which could help us use
>> it for other properties too (if we need to). It does look better than the
>> current change that I have done, because the Java code then doesn't have to
>> worry about how that default value is sourced. We can then just update the
>> scripts to set up the default for the log.dir appropriately.
>> >
>> >     I can work towards adding support for it and will update this patch
>> once it's ready.
>> >
>> >     As for:
>> >
>> >     > Something seems odd about force overriding the working directory
>> of the process just to set the log directory.
>> >
>> >     Sorry, I don't understand what you meant there. Is it something
>> about the change that was done to the scripts?
>>
>> I guess what I mean is: is there any other reason you might care about
>> the working directory of the process? If so we probably don't want to force
>> it to be the Kafka directory. If not it may actually be fine and in that
>> case I think having relative paths work is nice. I don't personally know
>> the answer to this, what is "good practice" for a server process?
>>
>>
>> - Jay
>>
>>
>> -----------------------------------------------------------
>> This is an automatically generated e-mail. To reply, visit:
>> https://reviews.apache.org/r/30403/#review70168
>> -----------------------------------------------------------
>>
>>
>>  On Jan. 29, 2015, 6:24 a.m., Jaikiran Pai wrote:
>> >
>> > -----------------------------------------------------------
>> > This is an automatically generated e-mail. To reply, visit:
>> > https://reviews.apache.org/r/30403/
>> > -----------------------------------------------------------
>> >
>> > (Updated Jan. 29, 2015, 6:24 a.m.)
>> >
>> >
>> > Review request for kafka.
>> >
>> >
>> > Bugs: KAFKA-1906
>> >     https://issues.apache.org/jira/browse/KAFKA-1906
>> >
>> >
>> > Repository: kafka
>> >
>> >
>> > Description
>> > -------
>> >
>> > KAFKA-1906 Default the Kafka data log directory to
>> $KAFKA_HOME/data/kafka-logs directory, where KAFKA_HOME is the Kafka
>> installation directory
>> >
>> >
>> > Diffs
>> > -----
>> >
>> >   bin/kafka-run-class.sh 881f578a8f5c796fe23415b978c1ad35869af76e
>> >   bin/windows/kafka-run-class.bat
>> 9df3d2b45236b4f06d55a89c84afcf0ab9f5d0f2
>> >   config/server.properties 1614260b71a658b405bb24157c8f12b1f1031aa5
>> >   core/src/main/scala/kafka/server/KafkaConfig.scala
>> 6d74983472249eac808d361344c58cc2858ec971
>> >   core/src/test/scala/unit/kafka/server/KafkaConfigTest.scala
>> 82dce80d553957d8b5776a9e140c346d4e07f766
>> >
>> > Diff: https://reviews.apache.org/r/30403/diff/
>> >
>> >
>> > Testing
>> > -------
>> >
>> > The change here involves updating the Kafka scripts (for Windows and *
>> nix) to infer and setup KAFKA_HOME environment variable. This value is then
>> used by the KafkaConfig to decide what path to default to for the Kafka
>> data logs, in the absence of any explicitly set log.dirs (or log.dir)
>> properties.
>> >
>> > Care has been taken to ensure that other mechanism which might
>> presently be bypassing the Kafka scripts, will still continue to function,
>> since in the absence of KAFKA_HOME environment property value, we fall back
>> to /tmp/kafka-logs (the present default) as the default data log directory
>> >
>> > Existing tests have been run to ensure that this change maintains
>> backward compatibility (i.e. doesn't fail when KAFKA_HOME isn't
>> available/set) and 2 new test methods have been added to the
>> KafkaConfigTest to ensure that this change works.
>> >
>> > Although the change has been made to both .sh and .bat files, to
>> support this, I haven't actually tested this change on a Windows OS and
>> would appreciate if someone can test this there and let me know if they run
>> into any issues.
>> >
>> >
>> > Thanks,
>> >
>> > Jaikiran Pai
>> >
>> >
>>
>>
>
>
>  --
>  Jeff Holoman
> Systems Engineer
> 678-612-9519
>
>
>
>
>


-- 
Jeff Holoman
Systems Engineer