Make SecretsSettingsSource deserialize complex types (#3194)

* Make SecretsSettingsSource deserialize complex types

* Add change notes

changes/2917-davidmreed.md

@@ -0,0 +1 @@
+Make `SecretsSettingsSource` parse values being assigned to fields of complex types when sourced from a secrets file, just as when sourced from environment variables.

pydantic/env_settings.py

@@ -216,7 +216,14 @@ class SecretsSettingsSource:
             for env_name in field.field_info.extra['env_names']:
                 path = secrets_path / env_name
                 if path.is_file():
-                    secrets[field.alias] = path.read_text().strip()
+                    secret_value = path.read_text().strip()
+                    if field.is_complex():
+                        try:
+                            secret_value = settings.__config__.json_loads(secret_value)
+                        except ValueError as e:
+                            raise SettingsError(f'error parsing JSON for "{env_name}"') from e
+
+                    secrets[field.alias] = secret_value
                 elif path.exists():
                     warnings.warn(
                         f'attempted to load secret file "{path}" but found a {path_type(path)} instead.',

tests/test_settings.py

@@ -830,6 +830,33 @@ def test_secrets_path_url(tmp_path):
     assert Settings().dict() == {'foo': 'http://www.example.com', 'bar': SecretStr('snap')}
 
 
+def test_secrets_path_json(tmp_path):
+    p = tmp_path / 'foo'
+    p.write_text('{"a": "b"}')
+
+    class Settings(BaseSettings):
+        foo: Dict[str, str]
+
+        class Config:
+            secrets_dir = tmp_path
+
+    assert Settings().dict() == {'foo': {'a': 'b'}}
+
+
+def test_secrets_path_invalid_json(tmp_path):
+    p = tmp_path / 'foo'
+    p.write_text('{"a": "b"')
+
+    class Settings(BaseSettings):
+        foo: Dict[str, str]
+
+        class Config:
+            secrets_dir = tmp_path
+
+    with pytest.raises(SettingsError, match='error parsing JSON for "foo"'):
+        Settings()
+
+
 def test_secrets_missing(tmp_path):
     class Settings(BaseSettings):
         foo: str