title: GitHub sphinx-action can't find target Python modules and builds an empty sphinx doc
body: <h3>Tl;dr</h3>
  <p>When I create a sphinx doc locally it builds as expected, but the <a href="https://github.com/ammaraskar/sphinx-action" rel="nofollow noreferrer">GitHub Sphinx Build Action</a> creates an empty doc. It must have to do with the sphinx-action not finding the target python modules as specified in <code>conf.py</code>.</p>
  <p>Any ideas to configure the sphinx-action or <code>conf.py</code> correctly?</p>
  <h3>Expected Sphinx Doc</h3>
  <p>When I build the sphinx doc locally on my machine via <code>cd docs/ &amp;&amp; make html</code> the resulting html looks as expected</p>
  <p><img src="https://user-images.githubusercontent.com/7808560/89300342-5b01aa00-d668-11ea-9e97-86ae469735a2.png" alt="expected_sphinx_doc" /></p>
  <h3>Empty Sphinx Doc generated by sphinx-action</h3>
  <p>My <code>.github/workflows/sphinx_action.yml</code> includes</p>
  <pre><code>    steps:
      # Checkout repo
      - uses: actions/checkout@v2
      # Build sphinx doc
      - uses: ammaraskar/sphinx-action@master
        with:
          docs-folder: &quot;docs/&quot;
  </code></pre>
  <p>and generates an empty skeleton of a Sphinx Doc</p>
  <p><img src="https://user-images.githubusercontent.com/7808560/89301152-93ee4e80-d669-11ea-94ad-83d8f6cfcf54.png" alt="output_shpinx_doc" /></p>
  <h3>Project Setup</h3>
  Project Structure
  <pre><code>.
  ├── docs
  │   ├── conf.py
  │   ├── index.rst
  │   ├── make.bat
  │   ├── Makefile
  │   ├── requirements.txt
  │   └── sync.log
  ├── .github
  │   └── workflows
  │       └── sphinx_action.yml
  ├── .gitignore
  ├── mypackage
  │   ├── __init__.py
  │   ├── subfolder
  │   │   ├── __init__.py
  │   │   └── subclass.py
  │   └── superclass.py
  ├── Pipfile
  ├── Pipfile.lock
  └── README.md
  </code></pre>
  <p><strong><code>conf.py</code> Configuration</strong></p>
  <p>My <code>docs/conf.py</code> looks as follows. (Mind that I added three entries to the <code>sys.path</code> manually in order to make Sphinx find all python modules.)</p>
  <pre class="lang-py prettyprint-override"><code># Configuration file for the Sphinx documentation builder.
  #
  # This file only contains a selection of the most common options. For a full
  # list see the documentation:
  # https://www.sphinx-doc.org/en/master/usage/configuration.html
  
  
  # -- Path setup --------------------------------------------------------------
  
  # If extensions (or modules to document with autodoc) are in another directory,
  # add these directories to sys.path here. If the directory is relative to the
  # documentation root, use os.path.abspath to make it absolute, like shown here.
  #
  import os
  import sys
  from m2r import MdInclude
  
  sys.path.insert(0, os.path.abspath('..'))
  sys.path.insert(0, os.path.abspath('../mypackage'))
  sys.path.insert(0, os.path.abspath('../mypackage/subfolder'))
  
  
  # -- Project information -----------------------------------------------------
  
  project = 'MyPackage'
  copyright = ''
  author = 'Testuser'
  
  
  # -- General configuration ---------------------------------------------------
  
  # Add any Sphinx extension module names here, as strings. They can be
  # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
  # ones.
  extensions = ['sphinx.ext.autodoc',
                'recommonmark'
  ]
  
  # Add any paths that contain templates here, relative to this directory.
  templates_path = ['_templates']
  
  #
  source_suffix = ['.rst', '.md']
  
  # List of patterns, relative to source directory, that match files and
  # directories to ignore when looking for source files.
  # This pattern also affects html_static_path and html_extra_path.
  exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
  
  # document the init of a class, too
  autoclass_content = 'both'
  
  # -- Options for HTML output -------------------------------------------------
  
  # The theme to use for HTML and HTML Help pages.  See the documentation for
  # a list of builtin themes.
  #
  html_theme = 'nature'
  
  # Add any paths that contain custom static files (such as style sheets) here,
  # relative to this directory. They are copied after the builtin static files,
  # so a file named &quot;default.css&quot; will overwrite the builtin &quot;default.css&quot;.
  html_static_path = ['_static']
  
  # from m2r to make `mdinclude` work
  def setup(app):
      config = {
          # 'url_resolver': lambda url: github_doc_root + url,
          'auto_toc_tree_section': 'Contents',
          'enable_eval_rst': True,
      }
  
      # from m2r to make `mdinclude` work
      app.add_config_value('no_underscore_emphasis', False, 'env')
      app.add_config_value('m2r_parse_relative_links', False, 'env')
      app.add_config_value('m2r_anonymous_references', False, 'env')
      app.add_config_value('m2r_disable_inline_math', False, 'env')
      app.add_directive('mdinclude', MdInclude)
  
  </code></pre>
  <p><strong>Pipfile</strong></p>
  <pre><code>[[source]]
  verify_ssl = true
  url = &quot;https://pypi.org/simple&quot;
  name = &quot;pypi&quot;
  
  [dev-packages]
  
  [packages]
  m2r = {index = &quot;pypi&quot;,version = &quot;==0.2.1&quot;}
  pandas = {index = &quot;pypi&quot;,version = &quot;==1.0.3&quot;}
  sphinx = {index = &quot;pypi&quot;,version = &quot;==3.1.0&quot;}
  recommonmark = {index = &quot;pypi&quot;,version = &quot;==0.6.0&quot;}
  mypackage = &quot;*&quot;
  
  [requires]
  python_version = &quot;3.8&quot;
  </code></pre>
  <p><em>Note:</em> I posted this question also as an <a href="https://github.com/ammaraskar/sphinx-action/issues/17" rel="nofollow noreferrer">issue in the GitHub repo of the sphinx-action</a>.</p>