fix(k8s): UID validation for valid context names (#7880)

Co-authored-by: Pepe Fagoaga <pepe@prowler.com>

api/src/backend/api/models.py

@@ -242,7 +242,7 @@ class Provider(RowLevelSecurityProtectedModel):
     @staticmethod
     def validate_kubernetes_uid(value):
         if not re.match(
-            r"^[a-z0-9][A-Za-z0-9_.:\/-]{1,250}$",
+            r"^[a-zA-Z0-9][a-zA-Z0-9._@:\/-]{1,250}$",
             value,
         ):
             raise ModelValidationError(

api/src/backend/api/tests/test_views.py

@@ -914,6 +914,16 @@ class TestProviderViewSet:
                     "uid": "gke_aaaa-dev_europe-test1_dev-aaaa-test-cluster-long-name-123456789",
                     "alias": "GKE",
                 },
+                {
+                    "provider": "kubernetes",
+                    "uid": "gke_project/cluster-name",
+                    "alias": "GKE",
+                },
+                {
+                    "provider": "kubernetes",
+                    "uid": "admin@k8s-demo",
+                    "alias": "test",
+                },
                 {
                     "provider": "azure",
                     "uid": "8851db6b-42e5-4533-aa9e-30a32d67e875",