Last updated：2023-05-23 18:05:41
Cluster AutoScaler (CA) is an add-on that is used to automatically scale nodes of a Kubernetes cluster. When the capacity of a cluster is insufficient, CA automatically creates a new node by calling Cloud Provider. When the utilization of a node is lower than 50% for more than 10 minutes, CA deletes the node to reduce costs.
CA checks whether a cluster has sufficient resources to schedule newly created pods every 10 seconds. If resources are insufficient, CA calls Cloud Provider to create a new node.
Whenever the Kubernetes scheduler cannot find a node to schedule a pod, the scheduler sets the PodCondition of the pod to false and the reason to unschedulable. CA checks for unschedulable pods at the specified interval. If an unschedulable pod exists, CA creates a node to schedule the pod.
If a cluster has more than one node pool, you can specify the policy for selecting the node pool to scale out. The following options are supported:
CA checks resource usage of nodes at the specified interval, which is 10 seconds by default. If the resource utilization of a node is lower than 50% (default value) for 10 minutes, and the pods on this node can be moved to other nodes, CA automatically deletes the node from the cluster. In this case, the pods on the node are automatically scheduled to other nodes.
A node will not be scaled in if the pods on this node meet one of the following conditions:
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