feat: add PYTHON_DOTENV_DISABLED flag to disable load_dotenv (fixes #510) (#569)

Co-authored-by: Saurabh Kumar <theskumar@users.noreply.github.com>

Author: matthewfranglen

README.md

@@ -134,6 +134,10 @@ Optional flags:
 - `-o` to override existing variables.
 - `-v` for increased verbosity.
 
+### Disable load_dotenv
+
+Set `PYTHON_DOTENV_DISABLED=1` to disable `load_dotenv()` from loading .env files or streams. Useful when you can't modify third-party package calls or in production.
+
 ## Command-line Interface
 
 A CLI interface `dotenv` is also included, which helps you manipulate the `.env` file

src/dotenv/main.py

@@ -350,6 +350,12 @@ def load_dotenv(
  of `find_dotenv()`, you can explicitly call `find_dotenv()` and pass the result
  to this function as `dotenv_path`.
  """
+ if _load_dotenv_disabled():
+ logger.debug(
+"python-dotenv: .env loading disabled by PYTHON_DOTENV_DISABLED environment variable"
+)
+ return False
+
  if dotenv_path is None and stream is None:
  dotenv_path = find_dotenv()
 
@@ -398,3 +404,12 @@ def dotenv_values(
  override=True,
  encoding=encoding,
  ).dict()
+
+def _load_dotenv_disabled() -> bool:
+ """
+ Determine if dotenv loading has been disabled.
+ """
+ if "PYTHON_DOTENV_DISABLED" not in os.environ:
+ return False
+ value = os.environ["PYTHON_DOTENV_DISABLED"].casefold()
+ return value in {"1", "true", "t", "yes", "y"}

tests/test_main.py

@@ -245,6 +245,130 @@ def test_load_dotenv_existing_file(dotenv_path):
  assert os.environ == {"a": "b"}
 
 
+@pytest.mark.parametrize(
+ "flag_value",
+ [
+ "true",
+ "yes",
+ "1",
+ "t",
+ "y",
+ "True",
+ "Yes",
+ "TRUE",
+ "YES",
+ "T",
+ "Y",
+ ],
+)
+def test_load_dotenv_disabled(dotenv_path, flag_value):
+ expected_environ = {"PYTHON_DOTENV_DISABLED": flag_value}
+ with mock.patch.dict(os.environ, {"PYTHON_DOTENV_DISABLED": flag_value}, clear=True):
+ dotenv_path.write_text("a=b")
+
+ result = dotenv.load_dotenv(dotenv_path)
+
+ assert result is False
+ assert os.environ == expected_environ
+
+
+@pytest.mark.parametrize(
+ "flag_value",
+ [
+ "true",
+ "yes",
+ "1",
+ "t",
+ "y",
+ "True",
+ "Yes",
+ "TRUE",
+ "YES",
+ "T",
+ "Y",
+ ],
+)
+def test_load_dotenv_disabled_notification(dotenv_path, flag_value):
+ with mock.patch.dict(os.environ, {"PYTHON_DOTENV_DISABLED": flag_value}, clear=True):
+ dotenv_path.write_text("a=b")
+
+ logger = logging.getLogger("dotenv.main")
+ with mock.patch.object(logger, "debug") as mock_debug:
+ result = dotenv.load_dotenv(dotenv_path)
+
+ assert result is False
+ mock_debug.assert_called_once_with(
+"python-dotenv: .env loading disabled by PYTHON_DOTENV_DISABLED environment variable"
+ )
+
+
+@pytest.mark.parametrize(
+ "flag_value",
+ [
+ "",
+ "false",
+ "no",
+ "0",
+ "f",
+ "n",
+ "False",
+ "No",
+ "FALSE",
+ "NO",
+ "F",
+ "N",
+ ],
+)
+def test_load_dotenv_enabled(dotenv_path, flag_value):
+ expected_environ = {"PYTHON_DOTENV_DISABLED": flag_value, "a": "b"}
+ with mock.patch.dict(os.environ, {"PYTHON_DOTENV_DISABLED": flag_value}, clear=True):
+ dotenv_path.write_text("a=b")
+
+ result = dotenv.load_dotenv(dotenv_path)
+
+ assert result is True
+ assert os.environ == expected_environ
+
+
+@pytest.mark.parametrize(
+ "flag_value",
+ [
+ "",
+ "false",
+ "no",
+ "0",
+ "f",
+ "n",
+ "False",
+ "No",
+ "FALSE",
+ "NO",
+ "F",
+ "N",
+ ],
+)
+def test_load_dotenv_enabled_no_notification(dotenv_path, flag_value):
+ with mock.patch.dict(os.environ, {"PYTHON_DOTENV_DISABLED": flag_value}, clear=True):
+ dotenv_path.write_text("a=b")
+
+ logger = logging.getLogger("dotenv.main")
+ with mock.patch.object(logger, "debug") as mock_debug:
+ result = dotenv.load_dotenv(dotenv_path)
+
+ assert result is True
+ mock_debug.assert_not_called()
+
+
+@mock.patch.dict(os.environ, {}, clear=True)
+def test_load_dotenv_doesnt_disable_itself(dotenv_path):
+ dotenv_path.write_text("PYTHON_DOTENV_DISABLED=true")
+
+ result = dotenv.load_dotenv(dotenv_path)
+
+ assert result is True
+ assert os.environ == {"PYTHON_DOTENV_DISABLED": "true"}
+
+
 def test_load_dotenv_no_file_verbose():
  logger = logging.getLogger("dotenv.main")