Avoid effects of YAML tags in get_deps

mkdocs/commands/get_deps.py

@@ -4,19 +4,38 @@ import dataclasses
 import datetime
 import functools
 import logging
+import sys
 from typing import Mapping, Sequence
 
+if sys.version_info >= (3, 10):
+    from importlib.metadata import EntryPoint, entry_points
+else:
+    from importlib_metadata import EntryPoint, entry_points
+
 import yaml
 
 from mkdocs import utils
 from mkdocs.config.base import _open_config_file
-from mkdocs.plugins import EntryPoint, entry_points
 from mkdocs.utils.cache import download_and_cache_url
 
 log = logging.getLogger(__name__)
 
 # Note: do not rely on functions in this module, it is not public API.
 
+
+class YamlLoader(yaml.SafeLoader):
+    pass
+
+
+# Prevent errors from trying to access external modules which may not be installed yet.
+YamlLoader.add_constructor("!ENV", lambda loader, node: None)  # type: ignore
+YamlLoader.add_multi_constructor(
+    "tag:yaml.org,2002:python/name:", lambda loader, suffix, node: None
+)
+YamlLoader.add_multi_constructor(
+    "tag:yaml.org,2002:python/object/apply:", lambda loader, suffix, node: None
+)
+
 NotFound = ()
 
 
@@ -76,7 +95,7 @@ def get_deps(projects_file_url: str, config_file_path: str | None = None) -> Non
         config_file_path: Non-default path to mkdocs.yml.
     """
     with _open_config_file(config_file_path) as f:
-        cfg = utils.yaml_load(f)
+        cfg = utils.yaml_load(f, loader=YamlLoader)  # type: ignore
 
     if all(c not in cfg for c in ('site_name', 'theme', 'plugins', 'markdown_extensions')):
         log.warning("The passed config file doesn't seem to be a mkdocs.yml config file")

mkdocs/utils/__init__.py

@@ -63,7 +63,7 @@ def get_yaml_loader(loader=yaml.Loader):
     return Loader
 
 
-def yaml_load(source: IO | str, loader: type[yaml.Loader] | None = None) -> dict[str, Any]:
+def yaml_load(source: IO | str, loader: type[yaml.BaseLoader] | None = None) -> dict[str, Any]:
     """Return dict of source YAML file using loader, recursively deep merging inherited parent."""
     Loader = loader or get_yaml_loader()
     result = yaml.load(source, Loader=Loader)