feat(observability): add Prometheus/Grafana/Loki/Alertmanager/Alloy stack and remove legacy Monitoring UI

backend/src/media_library_viewer_api/config.py

@@ -23,6 +23,7 @@ class Settings(BaseSettings):
 
     # Logging
     log_level: str = "INFO"
+    log_format: str = "text"  # "text" or "json"
 
     # Auth / OIDC (Authentik-compatible JWT validation)
     auth_enabled: bool = False
@@ -48,7 +49,6 @@ class Settings(BaseSettings):
     ssh_port: int = 22
     ssh_key_directory: str = ""
     ssh_key_name: str = ""
-    ssh_key_file: str = "/run/secrets/ssh_private_key"
     ssh_password: str = ""
     ssh_known_hosts_path: str = ""
 
@@ -57,6 +57,12 @@ class Settings(BaseSettings):
     monitoring_poll_initial_delay_seconds: int = 20
     monitoring_action_retention_days: int = 30
 
+    # Observability
+    prometheus_enabled: bool = True
+    prometheus_file_sd_dir: str = "/app/backend/.cache/prometheus-file-sd"
+    alertmanager_url: str = "http://alertmanager:9093"
+    alertmanager_webhook_url: str = ""  # Optional receiver for alertmanager webhook notifications
+
     # Remote paths
     remote_media_root: str = ""
     remote_path_prefix: str = ""
@@ -72,8 +78,6 @@ class Settings(BaseSettings):
 
     @property
     def ssh_key_path(self) -> str:
-        if self.ssh_key_file:
-            return self.ssh_key_file
         if not self.ssh_key_directory or not self.ssh_key_name:
             return ""
         return str(Path(self.ssh_key_directory) / self.ssh_key_name)
@@ -82,7 +86,7 @@ class Settings(BaseSettings):
     def ssh_known_hosts_file(self) -> Path:
         return Path(self.ssh_known_hosts_path or ".cache/media_library_viewer/known_hosts")
 
-    model_config = {"env_file": ".env", "env_file_encoding": "utf-8", "extra": "ignore"}
+    model_config = {"env_file": ".env", "env_file_encoding": "utf-8", "extra": "ignore"}  # type: ignore[assignment]
 
 
 def _find_env_file() -> str | None: