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https://issues.apache.org/jira/browse/SAMZA-416?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14140927#comment-14140927
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Jay Kreps commented on SAMZA-416:
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>From my point of view the primary problem with the config is that the error
>messages are very hard to understand. I think this is a really important
>usability problem.
Philosophically I think doing config in a programming language is usually not
the right thing to do. I think the goal of configuration is to limit power so
that there can be a set of knobs you can turn that are known to be safe.
Basically I see the goal of configuration to provide simple intuitive knobs so
that later on (say in the middle of the night) you don't have to think very
hard. Usually engineers like to do config in code because it limits the number
of syntaxes they need to remember, but I think invariably this leads to leaking
complexity into the config. I also think if we did the config in something
other than java we would then actually be requiring people to know both java
and python which is a bit of a burden.
I think we could move the config to JSON and that would probably be better, but
in terms of things that would really move the project forward I actually think
the real critical problem is just fixing the error messages whatever the syntax.
I would be a little suspicious of pluggability. I think you really just need
one way to do this that doesn't totally suck. Making it pluggable doesn't
necessarily get you closer to that and makes documentation really hard.
> Samza Configuration DSL
> -----------------------
>
> Key: SAMZA-416
> URL: https://issues.apache.org/jira/browse/SAMZA-416
> Project: Samza
> Issue Type: New Feature
> Reporter: David Chen
>
> The user-facing language for Samza configurations is currently Java
> Properties. While this works for the time being and simple to implement, it
> is verbose and cumbersome for the end user.
> Since SAMZA-40 is opened to refactor the way Samza configuration is wired and
> SAMZA-348 is opened to allow Samza jobs to be configured through a stream, it
> is thus natural to consider a scripting model for configuring Samza jobs.
> One approach would be to implement a DSL in a scripting language like Python.
> Implementing a Python DSL is actually very easy to do, and there are many
> examples of Python DSLs in non-trivial use cases, most notably, [Google's
> build system,
> Blaze|http://google-engtools.blogspot.com/2011/08/build-in-cloud-how-build-system-works.html].
> I found [a GitHub Gist containing a more detailed example of a Blaze BUILD
> file|https://gist.github.com/wiseman/3834928]. Blaze also inspired a number
> of open source clones, most notably [Twitter
> Pants|http://pantsbuild.github.io/].
> Another idea, by [~jonbringhurst] from SAMZA-348:
> {quote}
> Regarding the client commands to create and modify Samza jobs (such as
> configure-job and run-job), it may be useful to review existing commands that
> perform a similar role:
> My personal favorite is Slurm's set of client commands, of which sbatch is
> probably the most relevant (http://www.schedmd.com/slurmdocs/sbatch.html).
> To go back a bit further in history, it might be a good idea to take a look
> at the POSIX qsub style command from PBS/Torque
> (http://docs.adaptivecomputing.com/torque/4-1-4/Content/topics/commands/qsub.htm).
> Moab's msub also follows this design.
> Regarding a possible DSL for building configuration, it may be useful to look
> at Slurm's lua callback for job configuration (warning, GPLv2 code)
> https://github.com/SchedMD/slurm/blob/master/contribs/lua/job_submit.lua
> {quote}
> We could, of course, have both a command line tool and a DSL, and I am sure
> once Samza takes off, there will be people implementing DSLs for other
> language clients as well. The key would be to implement a standard interface
> for these different implementations to talk to.
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