Priorities for Scaling Node Pools¶
Prerequisites¶
To use node flavor priorities, the Autoscaler version must be 1.19.35, 1.21.28, 1.23.30, 1.25.20, or later. To balance load among AZs, the version must be 1.23.122, 1.25.117, 1.27.85, 1.28.52, or later.
Elastic Capacity Expansion Policies¶
Node pools are scaled according to their priorities and flavor priorities.
Predictive flavor filtering:
The predictive algorithm chooses proper flavors that meet the scheduling needs of pending pods from all node pools.
To schedule pods, various factors are considered, including whether the node resources meet the requested resources of the pods, and if the nodeSelector, nodeAffinity, and taints satisfy the conditions for pod scheduling.
Additionally, if certain node pool flavors experience scale-out failures, such as insufficient resources, and enter a 5-minute cooldown period, the scale-out algorithm will automatically exclude them from consideration during that time.
Node pool sorting by priority
Node pools are assigned priorities and sorted accordingly. The node pool with the highest priority is preferentially selected.
Flavor selection by priority
When multiple node pools have the same highest priority, the flavor with the highest priority is selected according to the following rules:
The flavor with the highest priority in each node pool is selected.
If multiple flavors have the same priority, choose the one that requires the least volume of resources to meet the pod scheduling requirements.
If multiple flavors require the minimum volume of resources, choose one based on a balanced distribution among AZs.
Troubleshooting if resources are insufficient or a creation failed
If the preferred flavor is unavailable due to insufficient resources or quota in the AZ, CCE will try to use the next priority flavor in the node pool, and the original instance will enter a 5-minute cooldown period.
If none of the flavors in a node pool can be used to create instances, CCE will try to use the next priority node pool to create instances.
Manual Capacity Expansion Policies¶
When manually scaling out a node pool, you can select a specified flavor. If the resources of the selected flavor are insufficient or the quota is insufficient, the scale-out will fail.
Configuring Priorities¶
For details about how to configure the priorities of node pool flavors, see Configuring an Auto Scaling Policy for a Cluster.