Ensure each instance of Config is unique

Replace the global variable `mkdocs.config.DEFAULT_SCHEMA` with
the function `mkdocs.config.defaults.get_schema()`. An instance is no
longer created on import (eliminating circular imports under certain
circumstances) and each call to `get_schema()` builds a new instance
of each object. Fixes #2289.

docs/about/release-notes.md

@@ -108,6 +108,10 @@ option. (#2092).
 The `mkdocs` theme now removes the sidebar when printing a page. This frees
 up horizontal space for better rendering of content like tables (#2193).
 
+The `mkdocs.config.DEFAULT_SCHEMA` global variable has been replaced with the
+function `mkdocs.config.defaults.get_schema()`, which ensures that each
+instance of the configuration is unique (#2289).
+
 ### Other Changes and Additions to Version 1.2
 
 * Bugfix: Properly process navigation child items in `_get_by_type` when

mkdocs/config/__init__.py

@@ -1,6 +1,4 @@
 from mkdocs.config.base import load_config, Config
-from mkdocs.config.defaults import DEFAULT_SCHEMA
 
 __all__ = [load_config.__name__,
-           Config.__name__,
-           'DEFAULT_SCHEMA']
+           Config.__name__]

mkdocs/config/base.py

@@ -187,8 +187,8 @@ def load_config(config_file=None, **kwargs):
     options['config_file_path'] = getattr(config_file, 'name', '')
 
     # Initialise the config with the default schema .
-    from mkdocs import config
-    cfg = Config(schema=config.DEFAULT_SCHEMA, config_file_path=options['config_file_path'])
+    from mkdocs.config.defaults import get_schema
+    cfg = Config(schema=get_schema(), config_file_path=options['config_file_path'])
     # First load the config file
     cfg.load_file(config_file)
     # Then load the options to overwrite anything in the config.

mkdocs/config/defaults.py

@@ -8,107 +8,109 @@ from mkdocs.config import config_options
 # isn't really needed either as we always sequentially process the schema other
 # than at initialisation when we grab the full set of keys for convenience.
 
-DEFAULT_SCHEMA = (
 
-    # Reserved for internal use, stores the mkdocs.yml config file.
-    ('config_file_path', config_options.Type(str)),
+def get_schema():
+    return (
 
-    # The title to use for the documentation
-    ('site_name', config_options.Type(str, required=True)),
+        # Reserved for internal use, stores the mkdocs.yml config file.
+        ('config_file_path', config_options.Type(str)),
 
-    # Defines the structure of the navigation.
-    ('nav', config_options.Nav()),
-    # TODO: remove this when the `pages` config setting is fully deprecated.
-    ('pages', config_options.Nav()),
+        # The title to use for the documentation
+        ('site_name', config_options.Type(str, required=True)),
 
-    # The full URL to where the documentation will be hosted
-    ('site_url', config_options.URL()),
+        # Defines the structure of the navigation.
+        ('nav', config_options.Nav()),
+        # TODO: remove this when the `pages` config setting is fully deprecated.
+        ('pages', config_options.Nav()),
 
-    # A description for the documentation project that will be added to the
-    # HTML meta tags.
-    ('site_description', config_options.Type(str)),
-    # The name of the author to add to the HTML meta tags
-    ('site_author', config_options.Type(str)),
+        # The full URL to where the documentation will be hosted
+        ('site_url', config_options.URL()),
 
-    # The MkDocs theme for the documentation.
-    ('theme', config_options.Theme(default='mkdocs')),
+        # A description for the documentation project that will be added to the
+        # HTML meta tags.
+        ('site_description', config_options.Type(str)),
+        # The name of the author to add to the HTML meta tags
+        ('site_author', config_options.Type(str)),
 
-    # The directory containing the documentation markdown.
-    ('docs_dir', config_options.Dir(default='docs', exists=True)),
+        # The MkDocs theme for the documentation.
+        ('theme', config_options.Theme(default='mkdocs')),
 
-    # The directory where the site will be built to
-    ('site_dir', config_options.SiteDir(default='site')),
+        # The directory containing the documentation markdown.
+        ('docs_dir', config_options.Dir(default='docs', exists=True)),
 
-    # A copyright notice to add to the footer of documentation.
-    ('copyright', config_options.Type(str)),
+        # The directory where the site will be built to
+        ('site_dir', config_options.SiteDir(default='site')),
 
-    # set of values for Google analytics containing the account IO and domain,
-    # this should look like, ['UA-27795084-5', 'mkdocs.org']
-    ('google_analytics', config_options.Type(list, length=2)),
+        # A copyright notice to add to the footer of documentation.
+        ('copyright', config_options.Type(str)),
 
-    # The address on which to serve the live reloading docs server.
-    ('dev_addr', config_options.IpAddress(default='127.0.0.1:8000')),
+        # set of values for Google analytics containing the account IO and domain,
+        # this should look like, ['UA-27795084-5', 'mkdocs.org']
+        ('google_analytics', config_options.Type(list, length=2)),
 
-    # If `True`, use `<page_name>/index.hmtl` style files with hyperlinks to
-    # the directory.If `False`, use `<page_name>.html style file with
-    # hyperlinks to the file.
-    # True generates nicer URLs, but False is useful if browsing the output on
-    # a filesystem.
-    ('use_directory_urls', config_options.Type(bool, default=True)),
+        # The address on which to serve the live reloading docs server.
+        ('dev_addr', config_options.IpAddress(default='127.0.0.1:8000')),
 
-    # Specify a link to the project source repo to be included
-    # in the documentation pages.
-    ('repo_url', config_options.RepoURL()),
+        # If `True`, use `<page_name>/index.hmtl` style files with hyperlinks to
+        # the directory.If `False`, use `<page_name>.html style file with
+        # hyperlinks to the file.
+        # True generates nicer URLs, but False is useful if browsing the output on
+        # a filesystem.
+        ('use_directory_urls', config_options.Type(bool, default=True)),
 
-    # A name to use for the link to the project source repo.
-    # Default, If repo_url is unset then None, otherwise
-    # "GitHub", "Bitbucket" or "GitLab" for known url or Hostname
-    # for unknown urls.
-    ('repo_name', config_options.Type(str)),
+        # Specify a link to the project source repo to be included
+        # in the documentation pages.
+        ('repo_url', config_options.RepoURL()),
 
-    # Specify a URI to the docs dir in the project source repo, relative to the
-    # repo_url. When set, a link directly to the page in the source repo will
-    # be added to the generated HTML. If repo_url is not set also, this option
-    # is ignored.
-    ('edit_uri', config_options.Type(str)),
+        # A name to use for the link to the project source repo.
+        # Default, If repo_url is unset then None, otherwise
+        # "GitHub", "Bitbucket" or "GitLab" for known url or Hostname
+        # for unknown urls.
+        ('repo_name', config_options.Type(str)),
 
-    # Specify which css or javascript files from the docs directory should be
-    # additionally included in the site.
-    ('extra_css', config_options.Type(list, default=[])),
-    ('extra_javascript', config_options.Type(list, default=[])),
+        # Specify a URI to the docs dir in the project source repo, relative to the
+        # repo_url. When set, a link directly to the page in the source repo will
+        # be added to the generated HTML. If repo_url is not set also, this option
+        # is ignored.
+        ('edit_uri', config_options.Type(str)),
 
-    # Similar to the above, but each template (HTML or XML) will be build with
-    # Jinja2 and the global context.
-    ('extra_templates', config_options.Type(list, default=[])),
+        # Specify which css or javascript files from the docs directory should be
+        # additionally included in the site.
+        ('extra_css', config_options.Type(list, default=[])),
+        ('extra_javascript', config_options.Type(list, default=[])),
 
-    # PyMarkdown extension names.
-    ('markdown_extensions', config_options.MarkdownExtensions(
-        builtins=['toc', 'tables', 'fenced_code'],
-        configkey='mdx_configs', default=[])),
+        # Similar to the above, but each template (HTML or XML) will be build with
+        # Jinja2 and the global context.
+        ('extra_templates', config_options.Type(list, default=[])),
 
-    # PyMarkdown Extension Configs. For internal use only.
-    ('mdx_configs', config_options.Private()),
+        # PyMarkdown extension names.
+        ('markdown_extensions', config_options.MarkdownExtensions(
+            builtins=['toc', 'tables', 'fenced_code'],
+            configkey='mdx_configs', default=[])),
 
-    # enabling strict mode causes MkDocs to stop the build when a problem is
-    # encountered rather than display an error.
-    ('strict', config_options.Type(bool, default=False)),
+        # PyMarkdown Extension Configs. For internal use only.
+        ('mdx_configs', config_options.Private()),
 
-    # the remote branch to commit to when using gh-deploy
-    ('remote_branch', config_options.Type(
-        str, default='gh-pages')),
+        # enabling strict mode causes MkDocs to stop the build when a problem is
+        # encountered rather than display an error.
+        ('strict', config_options.Type(bool, default=False)),
 
-    # the remote name to push to when using gh-deploy
-    ('remote_name', config_options.Type(str, default='origin')),
+        # the remote branch to commit to when using gh-deploy
+        ('remote_branch', config_options.Type(
+            str, default='gh-pages')),
 
-    # extra is a mapping/dictionary of data that is passed to the template.
-    # This allows template authors to require extra configuration that not
-    # relevant to all themes and doesn't need to be explicitly supported by
-    # MkDocs itself. A good example here would be including the current
-    # project version.
-    ('extra', config_options.SubConfig()),
+        # the remote name to push to when using gh-deploy
+        ('remote_name', config_options.Type(str, default='origin')),
 
-    # a list of plugins. Each item may contain a string name or a key value pair.
-    # A key value pair should be the string name (as the key) and a dict of config
-    # options (as the value).
-    ('plugins', config_options.Plugins(default=['search'])),
-)
+        # extra is a mapping/dictionary of data that is passed to the template.
+        # This allows template authors to require extra configuration that not
+        # relevant to all themes and doesn't need to be explicitly supported by
+        # MkDocs itself. A good example here would be including the current
+        # project version.
+        ('extra', config_options.SubConfig()),
+
+        # a list of plugins. Each item may contain a string name or a key value pair.
+        # A key value pair should be the string name (as the key) and a dict of config
+        # options (as the value).
+        ('plugins', config_options.Plugins(default=['search'])),
+    )

mkdocs/tests/base.py

@@ -32,7 +32,7 @@ def load_config(**cfg):
     if 'docs_dir' not in cfg:
         # Point to an actual dir to avoid a 'does not exist' error on validation.
         cfg['docs_dir'] = os.path.join(path_base, 'docs')
-    conf = config.Config(schema=config.DEFAULT_SCHEMA, config_file_path=cfg['config_file_path'])
+    conf = config.Config(schema=config.defaults.get_schema(), config_file_path=cfg['config_file_path'])
     conf.load_dict(cfg)
 
     errors_warnings = conf.validate()

mkdocs/tests/config/base_tests.py

@@ -12,7 +12,7 @@ class ConfigBaseTests(unittest.TestCase):
 
     def test_unrecognised_keys(self):
 
-        c = base.Config(schema=defaults.DEFAULT_SCHEMA)
+        c = base.Config(schema=defaults.get_schema())
         c.load_dict({
             'not_a_valid_config_option': "test"
         })
@@ -26,7 +26,7 @@ class ConfigBaseTests(unittest.TestCase):
 
     def test_missing_required(self):
 
-        c = base.Config(schema=defaults.DEFAULT_SCHEMA)
+        c = base.Config(schema=defaults.get_schema())
 
         errors, warnings = c.validate()
 

mkdocs/tests/config/config_tests.py

@@ -8,6 +8,7 @@ from tempfile import TemporaryDirectory
 import mkdocs
 from mkdocs import config
 from mkdocs.config import config_options
+from mkdocs.config import defaults
 from mkdocs.exceptions import ConfigurationError
 from mkdocs.tests.base import dedent
 
@@ -20,7 +21,7 @@ class ConfigTests(unittest.TestCase):
         self.assertRaises(ConfigurationError, load_missing_config)
 
     def test_missing_site_name(self):
-        c = config.Config(schema=config.DEFAULT_SCHEMA)
+        c = config.Config(schema=defaults.get_schema())
         c.load_dict({})
         errors, warnings = c.validate()
         self.assertEqual(len(errors), 1)
@@ -201,7 +202,7 @@ class ConfigTests(unittest.TestCase):
                 self.assertEqual({k: c['theme'][k] for k in iter(c['theme'])}, result['vars'])
 
     def test_empty_nav(self):
-        conf = config.Config(schema=config.DEFAULT_SCHEMA)
+        conf = config.Config(schema=defaults.get_schema())
         conf.load_dict({
             'site_name': 'Example',
             'config_file_path': os.path.join(os.path.abspath('.'), 'mkdocs.yml')
@@ -211,7 +212,7 @@ class ConfigTests(unittest.TestCase):
 
     def test_copy_pages_to_nav(self):
         # TODO: remove this when pages config setting is fully deprecated.
-        conf = config.Config(schema=config.DEFAULT_SCHEMA)
+        conf = config.Config(schema=defaults.get_schema())
         conf.load_dict({
             'site_name': 'Example',
             'pages': ['index.md', 'about.md'],
@@ -222,7 +223,7 @@ class ConfigTests(unittest.TestCase):
 
     def test_dont_overwrite_nav_with_pages(self):
         # TODO: remove this when pages config setting is fully deprecated.
-        conf = config.Config(schema=config.DEFAULT_SCHEMA)
+        conf = config.Config(schema=defaults.get_schema())
         conf.load_dict({
             'site_name': 'Example',
             'pages': ['index.md', 'about.md'],
@@ -266,3 +267,19 @@ class ConfigTests(unittest.TestCase):
 
             self.assertEqual(len(errors), 1)
             self.assertEqual(warnings, [])
+
+    def testConfigInstancesUnique(self):
+        conf = mkdocs.config.Config(mkdocs.config.defaults.get_schema())
+        conf.load_dict({'site_name': 'foo'})
+        conf.validate()
+        self.assertIsNone(conf['mdx_configs'].get('toc'))
+
+        conf = mkdocs.config.Config(mkdocs.config.defaults.get_schema())
+        conf.load_dict({'site_name': 'foo', 'markdown_extensions': [{"toc": {"permalink": "aaa"}}]})
+        conf.validate()
+        self.assertEqual(conf['mdx_configs'].get('toc'), {'permalink': 'aaa'})
+
+        conf = mkdocs.config.Config(mkdocs.config.defaults.get_schema())
+        conf.load_dict({'site_name': 'foo'})
+        conf.validate()
+        self.assertIsNone(conf['mdx_configs'].get('toc'))