Add Github Actions x86 and mac jobs to build python wheels

[janaknat]

multibuild added as a submodule. It is used for the building and testing process.

[janaknat]

Build log: https://github.com/janaknat/gensim/actions/runs/478819644

[mpenkov]

I think it should build the latest HEAD here. There's no point building the same commit every two weeks, is there?

[mpenkov]

Why do we need separate TRAVIS_ environment variables here? We aren't using Travis anymore.

Some of these values are redundant (e.g. MB_PYTHON_VERSION and TRAVIS_PYTHON_VERSION). Some of them are already available via the default environment variables exposed by Github Actions. Let's only keep the ones that we really need.

[mpenkov]

(if multibuild expects those variables to be there, it's definitely worth documenting that)

[mpenkov]

We don't need a separate step to pin these things. It's simpler to define them in the environment explicitly, right?

e.g.

env:
   TEST_DEPENDS: Morfessor==2.0.2a4 ...
```

[mpenkov]

I think you're over-depending on bash conditionals here. You're mixing actual build steps and configuration, so it's difficult to understand what's going on without reading through the entire workflow.

Isn't it possible to define the environment variables as part of the matrix? For example:

• add combinations explicitly
• exclude combinations

[mpenkov]

What is this for? If we don't need it, please remove it.

[mpenkov]

I think most of this step needs to go into the environment sub-sections of the build matrix.

[janaknat]

@mpenkov I've updated the branch and made the changes.

[mpenkov]

Suggested change

	branches: [ master ]
	branches: [ develop ]

Same below.

We use master for releases. PRs get merged onto develop, so we should be building from there.

[mpenkov]

This can be part of the matrix. You don't need a separate build step for this.

https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-syntax-for-github-actions#using-environment-variables-in-a-matrix

[mpenkov]

Same as above.

Having these variables defined in the matrix is better, because then we can see what's going on up front, instead of having to read the build script step by step.

[mpenkov]

There's a neat way to group log output in github actions:

https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions#grouping-log-lines

So we can do things like:

run: |
  echo ::group::Set up multibuild
  source multibuild/common_utils.sh
  source multibuild/travis_steps.sh
  source config.sh
  echo ::endgroup::

  echo ::group::before_install
  before_install
  echo ::endgroup::

and so on.

[mpenkov]

OK, that's looking better. Left you some more comments.

[janaknat]

@mpenkov Addressed the comments.

[mpenkov]

@janaknat I made some minor edits and merged your changes. Thank you for your contribution!

Please keep an eye on the new workflow - if there's anything else you need to add, please let me know via a PR. Thanks again!

[mpenkov]

@janaknat The wheels are getting built for each commit - this isn't what we wanted, right? They should run twice weekly and that's it.

https://github.com/RaRe-Technologies/gensim/actions/runs/491235040

Please have a look.

[janaknat]

@mpenkov Any pushes, PRs to develop will trigger a build, in addition to running twice a week.

[mpenkov]

Can you change that behavior? Building wheels on every push and PR is excessive. We only need them built once a week.

[janaknat]

Ok, I'll create a PR and change it to run twice a week.