Set encodings when reading config files (#2996)

Co-authored-by: Marcelo Trylesinski <[email protected]>

Author: secrett2633

docs/config.md

@@ -120,6 +120,18 @@ DEBUG = config('DEBUG') # lookups APP_DEBUG, returns "yes"
 ENVIRONMENT = config('ENVIRONMENT') # lookups APP_ENVIRONMENT, raises KeyError as variable is not defined
 ```
 
+## Custom encoding for environment files 
+
+By default, Starlette reads environment files using UTF-8 encoding. 
+You can specify a different encoding by setting `encoding` argument.
+
+```python title="myproject/settings.py"
+from starlette.config import Config
+
+# Using custom encoding for .env file
+config = Config(".env", encoding="latin-1")
+```
+
 ## A full example
 
 Structuring large applications can be complex. You need proper separation of

starlette/config.py

@@ -52,6 +52,7 @@ def __init__(
         env_file: str | Path | None = None,
         environ: Mapping[str, str] = environ,
         env_prefix: str = "",
+        encoding: str = "utf-8",
     ) -> None:
         self.environ = environ
         self.env_prefix = env_prefix
@@ -60,7 +61,7 @@ def __init__(
             if not os.path.isfile(env_file):
                 warnings.warn(f"Config file '{env_file}' not found.")
             else:
-                self.file_values = self._read_file(env_file)
+                self.file_values = self._read_file(env_file, encoding)
 
     @overload
     def __call__(self, key: str, *, default: None) -> str | None: ...
@@ -107,9 +108,9 @@ def get(
             return self._perform_cast(key, default, cast)
         raise KeyError(f"Config '{key}' is missing, and has no default.")
 
-    def _read_file(self, file_name: str | Path) -> dict[str, str]:
+    def _read_file(self, file_name: str | Path, encoding: str) -> dict[str, str]:
         file_values: dict[str, str] = {}
-        with open(file_name) as input_file:
+        with open(file_name, encoding=encoding) as input_file:
             for line in input_file.readlines():
                 line = line.strip()
                 if "=" in line and not line.startswith("#"):

tests/test_config.py

@@ -140,3 +140,10 @@ def test_config_with_env_prefix(tmpdir: Path, monkeypatch: pytest.MonkeyPatch) -
 
     with pytest.raises(KeyError):
         config.get("ENVIRONMENT")
+
+
+def test_config_with_encoding(tmpdir: Path) -> None:
+    path = tmpdir / ".env"
+    path.write_text("MESSAGE=Hello 世界\n", encoding="utf-8")
+    config = Config(path, encoding="utf-8")
+    assert config.get("MESSAGE") == "Hello 世界"