fix debug env var loading (#27)

- Fix debug being set to `"0"` being treated as `True` due to a lack of casting

Author: alexlambson

kirovy/settings/_base.py

@@ -31,7 +31,7 @@
 SECRET_KEY = get_env_var("SECRET_KEY", validation_callback=secret_key_validator)
 
 # SECURITY WARNING: don't run with debug turned on in production!
-DEBUG = get_env_var("DEBUG", False, validation_callback=not_allowed_on_prod)
+DEBUG = get_env_var("DEBUG", default=False, validation_callback=not_allowed_on_prod, value_type=bool)
 
 ALLOWED_HOSTS = get_env_var("ALLOWED_HOSTS", "localhost,mapdb-nginx").split(",")
 

kirovy/typing/__init__.py

@@ -1,6 +1,7 @@
 """
 Any types specific to our application should live in this package.
 """
+
 import uuid
 
 # import typing for re-export. This avoids having two different typing imports.
@@ -10,7 +11,7 @@
 # arg[0]: The key of the env var for the exception.
 # arg[1]: The value we fetched from the env var
 # No return, raise an error.
-SettingsValidationCallback = Callable[[str, Any], NoReturn]
+SettingsValidationCallback = Callable[[str, Any], None]
 
 
 FileExtension = str

kirovy/utils/settings_utils.py

@@ -4,19 +4,29 @@
 """
 
 import os
-from typing import Any, Optional, NoReturn
+from collections.abc import Callable
+
+from distutils.util import strtobool
+from typing import Any, Type
 
 from kirovy import exceptions
 from kirovy.typing import SettingsValidationCallback
 from kirovy.settings import settings_constants
 
 MINIMUM_SECRET_KEY_LENGTH = 32
+_NOT_SET = object()
+
+
+def _unvalidated_env_var(_: str, __: Any) -> None:
+    return
 
 
 def get_env_var(
     key: str,
-    default: Optional[Any] = None,
-    validation_callback: Optional[SettingsValidationCallback] = None,
+    default: Any | None = _NOT_SET,
+    validation_callback: SettingsValidationCallback = _unvalidated_env_var,
+    *,
+    value_type: Type[Callable[[object], Any]] = str,
 ) -> Any:
     """Get an env var and validate it.
 
@@ -25,16 +35,24 @@ def get_env_var(
 
     Do not provide defaults for e.g. passwords.
 
-    :param str key:
+    :param key:
         The env var key to search for.
-    :param Optional[Any] default:
+    :param default:
         The default value. Use to make an env var not raise an error if
         no env var is found. Never use for secrets.
         If you use with ``validation_callback`` then make sure your default value will
         pass your validation check.
-    :param Optional[SettingsValidationCallback] validation_callback:
+    :param validation_callback:
         A function to call on a value to make sure it's valid.
         Raises an exception if invalid.
+    :param value_type:
+        Convert the string from ``os.environ`` to this type. The type must be callable.
+        No validation is performed on the environment string before attempting to cast,
+        so you're responsible for handling cast errors.
+
+        .. note::
+
+            If you provide ``bool`` then we will use ``distutils.util.strtobool``.
     :return Any:
         The env var value
 
@@ -45,28 +63,29 @@ def get_env_var(
 
     """
 
-    value: Optional[Any] = os.environ.get(key)
-
-    if value is None:
-        value = default
+    value: str | None = os.environ.get(key)
 
-    if value is None:
+    if value is None and default is _NOT_SET:
         raise exceptions.ConfigurationException(key, "Env var is required and cannot be None.")
 
-    if validation_callback is not None:
-        validation_callback(key, value)
+    if value_type == bool:
+        value_type = strtobool
+
+    value = value_type(value) if value is not None else default
+
+    validation_callback(key, value)
 
     return value
 
 
-def secret_key_validator(key: str, value: str) -> NoReturn:
+def secret_key_validator(key: str, value: str) -> None:
     """Validate the secret key.
 
     :param str key:
         env var key.
     :param str value:
         The value found.
-    :return NoReturn:
+    :return:
 
     :raises exceptions.ConfigurationException:
     """

tests/test_settings_utils.py

@@ -2,7 +2,7 @@
 
 import pytest
 
-from kirovy import exceptions
+from kirovy import exceptions, typing as t
 from kirovy.utils import settings_utils
 
 
@@ -59,3 +59,24 @@ def test_run_environment_valid(run_environment: str, expect_error: bool):
         assert e
     else:
         settings_utils.get_env_var("meh", run_environment, settings_utils.run_environment_valid)
+
+
+@pytest.mark.parametrize(
+    "value,expected,value_type",
+    [
+        ("1", 1, int),
+        ("1.1", 1.1, float),
+        ("1", "1", str),
+        ("1", True, bool),
+        ("true", True, bool),
+        ("0", False, bool),
+        ("false", False, bool),
+    ],
+)
+def test_get_env_var_value(mocker, value: str, expected: t.Any, value_type: t.Type[t.Any]):
+    """Test the strings can be properly cast using the environment loader.
+
+    Necessary because ``environ.get`` always returns ``str | None``.
+    """
+    mocker.patch.dict(os.environ, {"test_get_env_var_value": value})
+    assert settings_utils.get_env_var("test_get_env_var_value", value_type=value_type) == expected