Fix type hinting for load_env (#2107)

* Deprecate `load_env` in favor of `env_prefix`

`load_env` both enabled/disabled environment variable parsing, while
also letting the user modify the env prefix. Deprecate the ability to
disable environment parsing, and add a new config variable to track the
user's desired prefix for environment-based configuration.

Resolves: #2102

* Add a few common .gitignore patterns

.gitignore

@@ -18,3 +18,6 @@ build/*
 .DS_Store
 dist/*
 pip-wheel-metadata/
+.pytest_cache/*
+.venv/*
+.vscode/*

sanic/app.py

@@ -43,7 +43,7 @@ from sanic.asgi import ASGIApp
 from sanic.base import BaseSanic
 from sanic.blueprint_group import BlueprintGroup
 from sanic.blueprints import Blueprint
-from sanic.config import BASE_LOGO, Config
+from sanic.config import BASE_LOGO, SANIC_PREFIX, Config
 from sanic.exceptions import (
     InvalidUsage,
     SanicException,
@@ -125,7 +125,8 @@ class Sanic(BaseSanic):
         router: Optional[Router] = None,
         signal_router: Optional[SignalRouter] = None,
         error_handler: Optional[ErrorHandler] = None,
-        load_env: bool = True,
+        load_env: Union[bool, str] = True,
+        env_prefix: Optional[str] = SANIC_PREFIX,
         request_class: Optional[Type[Request]] = None,
         strict_slashes: bool = False,
         log_config: Optional[Dict[str, Any]] = None,
@@ -150,7 +151,7 @@ class Sanic(BaseSanic):
         self._test_manager = None
         self.asgi = False
         self.blueprints: Dict[str, Blueprint] = {}
-        self.config = Config(load_env=load_env)
+        self.config = Config(load_env=load_env, env_prefix=env_prefix)
         self.configure_logging = configure_logging
         self.ctx = SimpleNamespace()
         self.debug = None

sanic/config.py

@@ -1,7 +1,8 @@
 from inspect import isclass
 from os import environ
 from pathlib import Path
-from typing import Any, Union
+from typing import Any, Dict, Optional, Union
+from warnings import warn
 
 from .utils import load_module_from_file_location, str_to_bool
 
@@ -41,7 +42,13 @@ DEFAULT_CONFIG = {
 
 
 class Config(dict):
-    def __init__(self, defaults=None, load_env=True, keep_alive=None):
+    def __init__(
+        self,
+        defaults: Dict[str, Union[str, bool, int, float, None]] = None,
+        load_env: Optional[Union[bool, str]] = True,
+        env_prefix: Optional[str] = SANIC_PREFIX,
+        keep_alive: Optional[int] = None,
+    ):
         defaults = defaults or {}
         super().__init__({**DEFAULT_CONFIG, **defaults})
 
@@ -50,9 +57,20 @@ class Config(dict):
         if keep_alive is not None:
             self.KEEP_ALIVE = keep_alive
 
-        if load_env:
+        if env_prefix != SANIC_PREFIX:
-            prefix = SANIC_PREFIX if load_env is True else load_env
+            if env_prefix:
-            self.load_environment_vars(prefix=prefix)
+                self.load_environment_vars(env_prefix)
+        elif load_env is not True:
+            if load_env:
+                self.load_environment_vars(prefix=load_env)
+            warn(
+                "Use of load_env is deprecated and will be removed in "
+                "21.12. Modify the configuration prefix by passing "
+                "env_prefix instead.",
+                DeprecationWarning,
+            )
+        else:
+            self.load_environment_vars(SANIC_PREFIX)
 
     def __getattr__(self, attr):
         try:

tests/test_config.py

@@ -59,14 +59,14 @@ def test_load_from_object_string_exception(app):
         app.config.load("test_config.Config.test")
 
 
-def test_auto_load_env():
+def test_auto_env_prefix():
     environ["SANIC_TEST_ANSWER"] = "42"
     app = Sanic(name=__name__)
     assert app.config.TEST_ANSWER == 42
     del environ["SANIC_TEST_ANSWER"]
 
 
-def test_auto_load_bool_env():
+def test_auto_bool_env_prefix():
     environ["SANIC_TEST_ANSWER"] = "True"
     app = Sanic(name=__name__)
     assert app.config.TEST_ANSWER is True
@@ -80,6 +80,12 @@ def test_dont_load_env():
     del environ["SANIC_TEST_ANSWER"]
 
 
+@pytest.mark.parametrize('load_env', [None, False, "", "MYAPP_"])
+def test_load_env_deprecation(load_env):
+    with pytest.warns(DeprecationWarning, match=r"21\.12"):
+        _ = Sanic(name=__name__, load_env=load_env)
+
+
 def test_load_env_prefix():
     environ["MYAPP_TEST_ANSWER"] = "42"
     app = Sanic(name=__name__, load_env="MYAPP_")
@@ -87,6 +93,14 @@ def test_load_env_prefix():
     del environ["MYAPP_TEST_ANSWER"]
 
 
+@pytest.mark.parametrize('env_prefix', [None, ""])
+def test_empty_load_env_prefix(env_prefix):
+    environ["SANIC_TEST_ANSWER"] = "42"
+    app = Sanic(name=__name__, env_prefix=env_prefix)
+    assert getattr(app.config, "TEST_ANSWER", None) is None
+    del environ["SANIC_TEST_ANSWER"]
+
+
 def test_load_env_prefix_float_values():
     environ["MYAPP_TEST_ROI"] = "2.3"
     app = Sanic(name=__name__, load_env="MYAPP_")
@@ -101,6 +115,27 @@ def test_load_env_prefix_string_value():
     del environ["MYAPP_TEST_TOKEN"]
 
 
+def test_env_prefix():
+    environ["MYAPP_TEST_ANSWER"] = "42"
+    app = Sanic(name=__name__, env_prefix="MYAPP_")
+    assert app.config.TEST_ANSWER == 42
+    del environ["MYAPP_TEST_ANSWER"]
+
+
+def test_env_prefix_float_values():
+    environ["MYAPP_TEST_ROI"] = "2.3"
+    app = Sanic(name=__name__, env_prefix="MYAPP_")
+    assert app.config.TEST_ROI == 2.3
+    del environ["MYAPP_TEST_ROI"]
+
+
+def test_env_prefix_string_value():
+    environ["MYAPP_TEST_TOKEN"] = "somerandomtesttoken"
+    app = Sanic(name=__name__, env_prefix="MYAPP_")
+    assert app.config.TEST_TOKEN == "somerandomtesttoken"
+    del environ["MYAPP_TEST_TOKEN"]
+
+
 def test_load_from_file(app):
     config = dedent(
         """

tests/test_keep_alive_timeout.py

@@ -1,4 +1,5 @@
 import asyncio
+import platform
 
 from asyncio import sleep as aio_sleep
 from json import JSONDecodeError
@@ -6,7 +7,6 @@ from os import environ
 
 import httpcore
 import httpx
-import platform
 import pytest
 
 from sanic_testing.testing import HOST, SanicTestClient