Shoot-cluster-unreachable state during transient infrastructure API failures

Gardener Shoot Lifecycle Management

The Gardener controller utilizes a heartbeat mechanism to monitor the health of managed Kubernetes clusters. When the control plane cannot communicate with a shoot cluster's API server, the cluster may transition into a shoot-cluster-unreachable state.

In environments where the underlying infrastructure provider experiences transient API latency or intermittent failures, the reconciliation loop may trigger rapid state transitions. This behavior can create notification noise within Prometheus and Alertmanager if the alerting thresholds are not aligned with the provider's recovery patterns.

Given the dependency on external cloud APIs, it is unclear how to distinguish between a genuine cluster failure and a transient provider-side timeout to prevent flapping alerts.

• What is the recommended configuration for Prometheus rules to suppress alerts during these transient reconciliation failures?
• Does the Gardener controller provide a mechanism to delay the shoot-cluster-unreachable state transition based on infrastructure provider health?