Use environment variables to get project and version slugs

Author: humitos

README.rst

@@ -59,12 +59,16 @@ Then in your ``conf.py`` you have to add ``versionwarning`` in the ``extensions`
 Enable it and setup the Read the Docs project's slug::
 
   versionwarning_enabled = True
-  versionwarning_project_slug = 'sphinx-version-warning'
 
 Remember to configure the ``version`` of your Sphinx project since it's the key for this to work properly::
 
   version = '0.0.1'
 
+.. warning::
+
+   If ``READTHEDOCS_VERSION`` variable is defined, the extension will use its value.
+   Otherwise, ``versionwarning_project_version`` will be used and if it's not defined, ``version`` as last resource.
+
 
 Customization
 -------------
@@ -87,7 +91,10 @@ versionwarning_message_placeholder (string)
    text to be replaced by the version number link from the message
 
 versionwarning_project_slug (string)
-   slug of the project under Read the Docs
+   slug of the project under Read the Docs (default to ``READTHEDOCS_PROJECT`` environment variable)
+
+versionwarning_project_version (string)
+   slug of the version for the current documentation (default to ``READTHEDOCS_VERSION`` environment variable or ``version`` variable from ``conf.py``)
 
 versionwarning_api_url (string)
    API URL to retrieve all versions for this project

versionwarning/__init__.py

@@ -5,6 +5,7 @@
 
 
 def setup(app):
+    import os
     import sphinx
     from .signals import process_version_warning_banner, generate_versionwarning_data_json
 
@@ -33,7 +34,8 @@ def setup(app):
     app.add_config_value('versionwarning_banner_id_div', 'version-warning-banner', 'html')
     app.add_config_value('versionwarning_body_default_selector', 'div.body', 'html')
     app.add_config_value('versionwarning_body_extra_selector', 'div.document', 'html')
-    app.add_config_value('versionwarning_project_slug', None, 'html')
+    app.add_config_value('versionwarning_project_slug', os.environ.get('READTHEDOCS_PROJECT', None), 'html')
+    app.add_config_value('versionwarning_project_version', os.environ.get('READTHEDOCS_VERSION', None), 'html')
 
     app.connect('doctree-resolved', process_version_warning_banner)
 

versionwarning/banner.py

@@ -89,7 +89,11 @@ def _default_admonition_type(self):
 
     @property
     def _current_doc_version_slug(self):
-        return self.app.config.version
+        return (
+            os.environ.get('READTHEDOCS_VERSION', None) or
+            self.app.config.versionwarning_project_version or
+            self.app.config.version
+        )
 
     @property
     def _latest_doc_version(self):