ReadTheDocs and pkg_resources fix

[aabmass]

Description

ReadTheDocs builds do not currently install the OTel packages in a virtualenv, but just update sys.path to include the modules. Autodoc imports the modules, which runs this code, but since the package isn't installed, pkg_resources.get_distribution() fails.

This change has opentelemetry-api and opentelemetry-sdk installed in the virtualenv to fix this.

Fixes #1144

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Ran the commands from https://readthedocs.org/projects/opentelemetry-python/builds/11937984/ and the issue is resolved.

$ python3 -m venv venv-docs && source venv-docs/bin/activate
$ python -m pip install --upgrade --no-cache-dir pip
$ python -m pip install --upgrade --no-cache-dir Pygments==2.3.1 setuptools==41.0.1 docutils==0.14 mock==1.0.1 pillow==5
.4.1 'alabaster>=0.7,<0.8,!=0.7.5' commonmark==0.8.1 recommonmark==0.5.0 'sphinx<2' 'sphinx-rtd-theme<0.5' 'readthedocs-sphinx-ext<1.1'
$ python -m pip install --exists-action=w --no-cache-dir -r docs-requirements.txt
$ sphinx-build -T -E -b html -d _build/doctrees-readthedocs -D language=en . _build/html

Checklist:

• Followed the style guidelines of this project

[codeboten]

This approach seems fine to me. Thanks for the fix!

[lzchen]

Would opencensus-exporter have the same issue?

[aabmass]

I believe it would if the autodoc directive included that util.py file, but it just includes it doesn't: https://github.com/open-telemetry/opentelemetry-python/blob/master/docs/exporter/opencensus/opencensus.rst

So all you see in the docs here is the docstring here:

opentelemetry-python/exporter/opentelemetry-exporter-opencensus/src/opentelemetry/exporter/opencensus/__init__.py

Lines 15 to 18 in b8a8016

	"""
	The **OpenCensus Exporter** allows to export traces and metrics using
	OpenCensus.
	"""

[aabmass]

I could fix that one up to do this as well though in case it's added in the future. Another option is to update the docs-requirements.txt file to actually install the opentelemetry-sdk/opentelemetry-api in the virtualenv so that pkg_resources.get_distrubution() works correctly.

[aabmass]

Gonna go with this second approach instead 👍