Secret test at startup

backend/app/core/config.py

@@ -5,6 +5,8 @@ from dataclasses import dataclass
 import os
 from pathlib import Path
 
+from cryptography.fernet import Fernet
+
 
 BASE_DIR = Path(__file__).resolve().parent.parent.parent
 DB_PATH = BASE_DIR / 'data' / 'linklog.db'
@@ -20,6 +22,7 @@ def normalize_public_url(value: str) -> str:
 
 @dataclass
 class Settings:
+    app_env: str = os.getenv('APP_ENV', 'development').lower()
     app_name: str = os.getenv('LINKLOG_APP_NAME', 'LinkLog')
     version: str = os.getenv('LINKLOG_VERSION', '0.1.0')
     database_url: str = os.getenv('LINKLOG_DATABASE_URL', f'sqlite:///{DB_PATH}')
@@ -59,3 +62,19 @@ class Settings:
 
 
 settings = Settings()
+
+
+def validate_configuration(values: Settings) -> None:
+    if values.app_env == 'production':
+        if not values.secret_key or values.secret_key == 'dev-secret-key-change-me':
+            raise RuntimeError('LINKLOG_SECRET_KEY must be configured in production')
+        if len(values.secret_key) < 32 or len(set(values.secret_key)) < 12:
+            raise RuntimeError('LINKLOG_SECRET_KEY must be at least 32 characters with sufficient entropy')
+        if not values.data_encryption_key:
+            raise RuntimeError('LINKLOG_DATA_ENCRYPTION_KEY must be configured in production')
+
+    if values.data_encryption_key:
+        try:
+            Fernet(values.data_encryption_key.encode('ascii'))
+        except (ValueError, UnicodeEncodeError) as error:
+            raise RuntimeError('LINKLOG_DATA_ENCRYPTION_KEY must be a valid Fernet key') from error