View the elastic strength of a worker node pool - Container Service for Kubernetes

A node pool scale-out can fail for reasons such as insufficient instance inventory or an unsupported ECS instance type in the specified zone. Elastic strength helps you evaluate the availability of your node pool configuration and the health of your instance supply. It also provides configuration recommendations. ACK displays node pools that have poor elastic strength.

Concepts

Elastic strength

A node pool’s elastic strength is the sum of the elastic strengths of all actually available resource pools. More available resource pools mean higher elastic strength. ACK displays this metric only when a node pool’s elastic strength is poor, which is a score of 0 or less.

Resource pool

During a scale-out, the node pool configuration acts as a template for new instances. This template includes settings such as the zone and instance type. Each combination of a zone and an instance type creates a resource pool. The number of resource pools depends on the number of zones and instance types you specify.

Actually available resource pool

Not all resource pools are always available. The scale-out process can be affected by inventory levels or resource constraints. For example, the c6e instance family supports enterprise SSDs but not standard SSDs. These factors can reduce the number of available resource pools below the theoretical maximum.

The following figure shows a node pool configured with two zones, two instance types, and a specific disk type. Although multiple resource pools exist in theory, only one is actually available. This is due to factors such as inventory, instance deployment status, and disk resource constraints.

View the elastic strength of a node pool

Log on to the Container Service Management Console . In the navigation pane on the left, click Clusters.
On the Clusters page, click the name of your cluster. In the navigation pane on the left, click Nodes > Node Pools.
On the Node Pools page, check the Status column to identify node pools with poor elastic strength. A poor rating indicates an inventory health score of 0 or less.

Click the Scalability Level: Weak button to view detailed information. The following figure shows the details.

Poor elastic strength and recommended solutions

To adjust the node pool configuration, see Create and manage a node pool. To improve high availability, select multiple vSwitches in different zones and configure multiple instance types that have sufficient inventory.

In the Scalability Details dialog box, view the assessment results in the Status column.

Type	Result	Recommended solution
Resource constraint check	Image and instance type mismatch	Adjust the instance types in the node pool.
	System disk and instance type mismatch	Adjust the instance types or system disk type in the node pool.
	Data disk and instance type mismatch	Adjust the instance types or data disk type in the node pool.
	Instance type does not support IPv6	Adjust the instance types in the node pool.
	vSwitch does not exist	Adjust the vSwitches in the node pool.
Instance inventory check	Instance type not deployed	Adjust the instance types in the node pool.
Instance inventory check	Instance type is out of stock	Adjust the instance types in the node pool.

References

For more information about node configuration recommendations, see ECS instance type configuration recommendations.