Allow setting os, dist, and language keys and defaults for them

[seankelly]

This is a fix for #32. I've been running it branched off 0.3 for months and rebased it off master and submitted. No idea yet if tests pass.

The gist is the master-side Travis config can set options for the os, dist, and language keys such as properties for the build to inherit. Defaults are also possible to set so dist can be something other than precise.

[mention-bot]

@seankelly, thanks for your PR! By analyzing the history of the files in this pull request, we identified @Jc2k, @tardyp and @rodrigc to be potential reviewers.

[tardyp]

I would like to have a README paragraph about this in order to better understand how this is supposed to work

[tardyp]

thanks for documenting it. I missed the job_options feature, which I like.
but I wonder if this is not a little bit too specific.

os and dist are imho not fitting very well to the matrix concept.
You won't need to generate all combination of os and dist, as win + debian_7 does not make sense.
while win + python / win + c makes sense for a matrix.

people might want to select different images based on other criterias.

os: linux_debian_7, langage=c, db=mysql => image=debian_mysql_gcc

so I think it would make more sense to have something like:

automatic_properties:
  image:
    - criterias:
         dist: linux_debian_7
         langage: c
         db: mysql
       value: debian_mysql_gcc 
     - # default
       value: default_builder 
  os:
    - criterias:
         dist: windows
      value: windows
    - value: linux

obviously this makes the implementation much more complicated than the 4 lines you have :-}

[seankelly]

win + debian_7 wouldn't be possible because it's hierarchical. The debian_7 would only appear under linux. A more complete example:

job_options:
  linux:
    debian_7:
      ...
  win:
    win_10:
      ..

Definitely can't handle looking up based on other criteria however, such as database. Might be able to do something without too much code. Perhaps select the criteria with the most parts that match, with the first to have that many matches winning.

[seankelly]

This PR sort of does two things:

1. Set dist, os, and language as properties along with making it more flexible beyond assuming language=python.
2. Looks up those properties to set other properties. The job_options part.

I've updated my internal version such that the second option is no longer needed. Because of that, if I remove that, would it be possible to merge this? I still need the dist, os, and language properties set.

[tardyp]

I dont see update in the code? did you forget to push?

[seankelly]

I haven't updated the code yet, it was a hypothetical question.

[seankelly]

Did the code change anyway. I think I removed the job_options part. It was much smaller than the rest.

[seankelly]

Rebased to fix conflicts.

[perlun]

@tardyp What do you think of this, does it need further updates to be mergeable?

[levitte]

I like a lot of what I see here and am prepared to give is a try or even help out.

Regarding os vs dist, If you look back at Travis, both are supported there, and it will simply ignore combinations that just don't fit together (i.e. there's presumably no Travis worker that supports that combination). I don't see an issue with that.

Another thing that's worth adding, which is also supported on Travis since not too long, is arch.

Looking back at #32, I think @vdsbenoit's idea to add the possibility to specify working combinations for the workers, no matter what form (I think that the possibility is sorely lacking for "native" Workers (i.e. not DockerWorker or HyperWorker)). Yes, I understand that there is a way to specify an image using DockerWorker, but doesn't that assume that all workers are able to run all desired images? That's hardly workable with multiple worker platforms, for example...