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On Wed, 2014-01-29 at 14:35 +0400, Alexander Ignatov wrote:
> Thank you for bringing this up, Trevor.
> 
> EDP gets more diverse and it's time to change its model.
> I totally agree with your proposal, but one minor comment.
> Instead of "savanna." prefix in job_configs wouldn't it be better to make it
> as "edp."? I think "savanna." is too more wide word for this.

+1, brilliant. EDP is perfect.  I was worried about the scope of
"savanna." too.

> And one more bureaucratic thing... I see you already started implementing it [1], 
> and it is named and goes as new EDP workflow [2]. I think new bluprint should be 
> created for this feature to track all code changes as well as docs updates. 
> Docs I mean public Savanna docs about EDP, rest api docs and samples.

Absolutely, I can make it new blueprint.  Thanks.

> [1] https://review.openstack.org/#/c/69712
> [2] https://blueprints.launchpad.net/openstack/?searchtext=edp-oozie-streaming-mapreduce
> 
> Regards,
> Alexander Ignatov
> 
> 
> 
> On 28 Jan 2014, at 20:47, Trevor McKay <tmckay at redhat.com> wrote:
> 
> > Hello all,
> > 
> > In our first pass at EDP, the model for job settings was very consistent
> > across all of our job types. The execution-time settings fit into this
> > (superset) structure:
> > 
> > job_configs = {'configs': {}, # config settings for oozie and hadoop
> > 	       'params': {},  # substitution values for Pig/Hive
> > 	       'args': []}    # script args (Pig and Java actions)
> > 
> > But we have some things that don't fit (and probably more in the
> > future):
> > 
> > 1) Java jobs have 'main_class' and 'java_opts' settings
> >   Currently these are handled as additional fields added to the
> > structure above.  These were the first to diverge.
> > 
> > 2) Streaming MapReduce (anticipated) requires mapper and reducer
> > settings (different than the mapred.xxxx.class settings for
> > non-streaming MapReduce)
> > 
> > Problems caused by adding fields
> > --------------------------------
> > The job_configs structure above is stored in the database. Each time we
> > add a field to the structure above at the level of configs, params, and
> > args, we force a change to the database tables, a migration script and a
> > change to the JSON validation for the REST api.
> > 
> > We also cause a change for python-savannaclient and potentially other
> > clients.
> > 
> > This kind of change seems bad.
> > 
> > Proposal: Borrow a page from Oozie and add "savanna." configs
> > -------------------------------------------------------------
> > I would like to fit divergent job settings into the structure we already
> > have.  One way to do this is to leverage the 'configs' dictionary.  This
> > dictionary primarily contains settings for hadoop, but there are a
> > number of "oozie.xxx" settings that are passed to oozie as configs or
> > set by oozie for the benefit of running apps.
> > 
> > What if we allow "savanna." settings to be added to configs?  If we do
> > that, any and all special configuration settings for specific job types
> > or subtypes can be handled with no database changes and no api changes.
> > 
> > Downside
> > --------
> > Currently, all 'configs' are rendered in the generated oozie workflow.
> > The "savanna." settings would be stripped out and processed by Savanna,
> > thereby changing that behavior a bit (maybe not a big deal)
> > 
> > We would also be mixing "savanna." configs with config_hints for jobs,
> > so users would potentially see "savanna.xxxx" settings mixed with oozie
> > and hadoop settings.  Again, maybe not a big deal, but it might blur the
> > lines a little bit.  Personally, I'm okay with this.
> > 
> > Slightly different
> > ------------------
> > We could also add a "'savanna-configs': {}" element to job_configs to
> > keep the configuration spaces separate.
> > 
> > But, now we would have 'savanna-configs' (or another name), 'configs',
> > 'params', and 'args'.  Really? Just how many different types of values
> > can we come up with? :)
> > 
> > I lean away from this approach.
> > 
> > Related: breaking up the superset
> > ---------------------------------
> > 
> > It is also the case that not every job type has every value type.
> > 
> >             Configs   Params    Args
> > Hive            Y         Y        N
> > Pig             Y         Y        Y
> > MapReduce       Y         N        N
> > Java            Y         N        Y
> > 
> > So do we make that explicit in the docs and enforce it in the api with
> > errors?
> > 
> > Thoughts? I'm sure there are some :)
> > 
> > Best,
> > 
> > Trevor
> > 
> > 
> > 
> > 
> > 
> > 
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> 
> 
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