kubernetes/kops · error

error assigning default machine type for nodes: %v

Error message

error assigning default machine type for nodes: %v

What it means

PopulateInstanceGroupSpec fills in defaults for an InstanceGroup during cluster/instance-group creation. When ig.Spec.MachineType is empty it calls defaultMachineType(cloud, cluster, ig); this error wraps any failure from that per-cloud default lookup. It means kOps could not choose a machine/flavor for the nodes role.

Source

Thrown at upup/pkg/fi/cloudup/populate_instancegroup_spec.go:136

		}
	} else {
		if ig.IsAPIServerOnly() && !featureflag.APIServerNodes.Enabled() {
			return nil, fmt.Errorf("apiserver nodes requires the APIServerNodes feature flag to be enabled")
		}
		if !featureflag.ExperimentalRoles.Enabled() {
			switch {
			case ig.Spec.Role.HasEtcd():
				return nil, fmt.Errorf("etcd nodes requires the ExperimentalNodes feature flag to be enabled")
			case ig.Spec.Role.HasScheduler():
				return nil, fmt.Errorf("scheduler nodes requires the ExperimentalNodes feature flag to be enabled")
			case ig.Spec.Role.HasKubeControllerManager():
				return nil, fmt.Errorf("kube-controller-manager nodes requires the ExperimentalNodes feature flag to be enabled")
			}
		}
		if ig.Spec.MachineType == "" {
			ig.Spec.MachineType, err = defaultMachineType(cloud, cluster, ig)
			if err != nil {
				return nil, fmt.Errorf("error assigning default machine type for nodes: %v", err)
			}
		}
		if ig.Spec.Manager != kops.InstanceManagerKarpenter {
			if ig.Spec.MinSize == nil {
				ig.Spec.MinSize = new(int32(2))
			}
			if ig.Spec.MaxSize == nil {
				ig.Spec.MaxSize = new(int32(2))
			}
		}
	}

	if ig.Spec.Image == "" {
		architecture, err := MachineArchitecture(cloud, ig.Spec.MachineType)
		if err != nil {
			return nil, fmt.Errorf("unable to determine machine architecture for InstanceGroup %q: %v", ig.ObjectMeta.Name, err)
		}
		ig.Spec.Image, err = defaultImage(cluster, channel, architecture)

View on GitHub (pinned to 4c8573c808)

Solutions

1. Set spec.machineType explicitly on the InstanceGroup so no default lookup is needed
2. Verify cloud credentials/permissions allow describing instance types or flavors
3. Check the wrapped error: if it names a missing/deprecated instance type, pick an available one in your region
4. Upgrade kOps if the region or machine family is newer than the kOps release

Example fix

// before
apiVersion: kops.k8s.io/v1alpha2
kind: InstanceGroup
metadata:
  name: nodes
spec:
  role: Node
// after
spec:
  role: Node
  machineType: t3.medium

// Go: ensure machineType set before calling PopulateInstanceGroupSpec
if ig.Spec.MachineType == "" {
    ig.Spec.MachineType = os.Getenv("KOPS_DEFAULT_MACHINE_TYPE") // or a known-good per-region type
}
if ig.Spec.MachineType == "" {
    return fmt.Errorf("instance group %s must set spec.machineType", ig.Name)
}

When it happens

Trigger: Running `kops create cluster` or `kops create instancegroup` (or `kops toolbox instance-selector`) without --set spec.machineType, while the cloud-specific default lookup fails — e.g. AWS DefaultInstanceType cannot find a valid instance type in the region, or Openstack DefaultInstanceType cannot match a flavor.

Common situations: New/unsupported AWS region lacking the default instance types; GCE/AWS quota issues; OpenStack flavor discovery failing due to misconfigured cloud credentials; clusters created with images/instance types deprecated in newer kOps versions.

Related errors

• error finding default machine type: %v
• did not find owner for node %q
• invalid InstanceGroup name: %v
• error building InstanceGroup from CAPI Machine: %w
• must specify %q label with cluster name to create instanceGr

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/f93fb99522b12715. Report an issue: GitHub.