Add source status API and enhance dashboard with data source checks

- Introduced a new API endpoint `/api/source-status/` to return the status of Prometheus and OpenStack data sources.
- Implemented lightweight health check functions for both Prometheus and OpenStack.
- Updated the dashboard template to display the status of data sources dynamically.
- Added tests for the new API endpoint to ensure correct functionality and response handling.
- Configured a cache timeout for source status checks to improve performance.

dashboard/openstack_utils/connect.py

@@ -3,6 +3,21 @@ from openstack.connection import Connection
 
 from watcher_visio.settings import OPENSTACK_CLOUD, OPENSTACK_REGION_NAME
 
+
+def check_openstack() -> dict:
+    """
+    Lightweight check that OpenStack is reachable (connection only).
+    Returns {"status": "ok"} or {"status": "error", "message": "..."}.
+    """
+    try:
+        conn = openstack.connect(cloud=OPENSTACK_CLOUD, region_name=OPENSTACK_REGION_NAME)
+        if conn is None:
+            return {"status": "error", "message": "No connection"}
+        return {"status": "ok"}
+    except Exception as e:
+        return {"status": "error", "message": str(e) or "Connection failed"}
+
+
 def get_connection() -> Connection:
     connection = openstack.connect(cloud=OPENSTACK_CLOUD, region_name=OPENSTACK_REGION_NAME)
     return connection