Add deployment-safe backend config and production-safe CORS defaults

Docs/Tasks.md

@@ -76,5 +76,5 @@ Reference: `Docs/Refactoring.md` for full analysis of each issue.
 2. ✅ Refactor dependency injection / explicit shared resources.
 3. ✅ Harden fail2ban client concurrency and packaging.
 4. ✅ Convert setup guard to a safer startup-driven model.
-5. Add deployment-safe configuration and production-ready CORS.
+5. ✅ Add deployment-safe configuration and production-ready CORS.
 6. Add lifecycle and concurrency regression tests.

backend/.env.example

@@ -8,6 +8,12 @@ BANGUI_DATABASE_PATH=bangui.db
 # Path to the fail2ban Unix domain socket.
 BANGUI_FAIL2BAN_SOCKET=/var/run/fail2ban/fail2ban.sock
 
+# Path to the fail2ban configuration directory used by the web UI.
+BANGUI_FAIL2BAN_CONFIG_DIR=/config/fail2ban
+
+# Shell command used to start fail2ban during recovery operations.
+BANGUI_FAIL2BAN_START_COMMAND=fail2ban-client start
+
 # Secret key used to sign session tokens. Use a long, random string.
 # Generate with: python -c "import secrets; print(secrets.token_hex(64))"
 BANGUI_SESSION_SECRET=replace-this-with-a-long-random-secret
@@ -23,4 +29,5 @@ BANGUI_LOG_LEVEL=info
 
 # Comma-separated list of allowed CORS origins when the frontend is served
 # from a different origin than the backend.
+# Leave this blank in production when the UI is served from the same origin.
 BANGUI_CORS_ALLOWED_ORIGINS=http://localhost:5173

backend/app/config.py

@@ -4,9 +4,15 @@ Follows pydantic-settings patterns: all values are prefixed with BANGUI_
 and validated at startup via the Settings singleton.
 """
 
-from pydantic import Field
+from pydantic import Field, field_validator
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
+from app.utils.constants import (
+    DEFAULT_DATABASE_PATH,
+    DEFAULT_FAIL2BAN_SOCKET,
+    DEFAULT_SESSION_DURATION_MINUTES,
+)
+
 
 class Settings(BaseSettings):
     """BanGUI runtime configuration.
@@ -18,11 +24,11 @@ class Settings(BaseSettings):
     """
 
     database_path: str = Field(
-        default="bangui.db",
+        default=DEFAULT_DATABASE_PATH,
         description="Filesystem path to the BanGUI SQLite application database.",
     )
     fail2ban_socket: str = Field(
-        default="/var/run/fail2ban/fail2ban.sock",
+        default=DEFAULT_FAIL2BAN_SOCKET,
         description="Path to the fail2ban Unix domain socket.",
     )
     session_secret: str = Field(
@@ -33,7 +39,7 @@ class Settings(BaseSettings):
         ),
     )
     session_duration_minutes: int = Field(
-        default=60,
+        default=DEFAULT_SESSION_DURATION_MINUTES,
         ge=1,
         description="Number of minutes a session token remains valid after creation.",
     )
@@ -41,14 +47,24 @@ class Settings(BaseSettings):
         default="UTC",
         description="IANA timezone name used when displaying timestamps in the UI.",
     )
-    cors_allowed_origins: list[str] = Field(
+    cors_allowed_origins: str | list[str] = Field(
-        default_factory=lambda: ["http://localhost:5173"],
+        default_factory=list,
         description=(
             "Comma-separated list of allowed CORS origins when the frontend is "
             "served from a different origin than the backend. "
             "Leave empty to disable cross-origin requests in production."
         ),
     )
+
+    @field_validator("cors_allowed_origins", mode="before")
+    @classmethod
+    def _normalize_cors_origins(cls, value: str | list[str] | None) -> list[str]:
+        if value is None:
+            return []
+        if isinstance(value, str):
+            return [origin.strip() for origin in value.split(",") if origin.strip()]
+        return value
+
     log_level: str = Field(
         default="info",
         description="Application log level: debug | info | warning | error | critical.",
@@ -72,8 +88,8 @@ class Settings(BaseSettings):
         default="fail2ban-client start",
         description=(
             "Shell command used to start (not reload) the fail2ban daemon during "
-            "recovery rollback.  Split by whitespace to build the argument list — "
+            "recovery rollback. Split by whitespace to build the argument list — "
-            "no shell interpretation is performed.  "
+            "no shell interpretation is performed. "
             "Example: 'systemctl start fail2ban' or 'fail2ban-client start'."
         ),
     )

backend/tests/test_main.py

@@ -48,3 +48,23 @@ def test_create_app_skips_cors_when_no_origins_are_configured() -> None:
     ]
 
     assert cors_middleware == []
+
+
+def test_create_app_disables_cors_by_default() -> None:
+    """The FastAPI app does not add CORS middleware when no origins are configured by environment."""
+    settings = Settings(
+        database_path="/tmp/test.db",
+        fail2ban_socket="/tmp/fake_fail2ban.sock",
+        fail2ban_config_dir="/tmp/fail2ban",
+        session_secret="test-secret-key-do-not-use-in-production",
+        session_duration_minutes=60,
+        timezone="UTC",
+        log_level="debug",
+    )
+
+    app = create_app(settings=settings)
+    cors_middleware = [
+        middleware for middleware in app.user_middleware if middleware.cls is CORSMiddleware
+    ]
+
+    assert cors_middleware == []