kubernetes/kops · error

control-plane InstanceGroup %s did not specify any Subnets

Error message

control-plane InstanceGroup %s did not specify any Subnets

What it means

Every control-plane InstanceGroup must explicitly list which subnets its machines run in, since control-plane placement is critical. If ig.IsControlPlane() and spec.subnets is empty, kOps refuses to guess and returns this error.

Source

Thrown at upup/pkg/fi/cloudup/populate_instancegroup_spec.go:173

		if err != nil {
			return nil, fmt.Errorf("unable to determine default image for instance group %q: %v", ig.ObjectMeta.Name, err)
		}
	}

	if ig.Spec.Tenancy != "" && ig.Spec.Tenancy != "default" {
		switch cluster.GetCloudProvider() {
		case kops.CloudProviderAWS:
			if _, ok := awsDedicatedInstanceExceptions[ig.Spec.MachineType]; ok {
				return nil, fmt.Errorf("invalid dedicated instance type: %s", ig.Spec.MachineType)
			}
		default:
			klog.Warning("Trying to set tenancy on non-AWS environment")
		}
	}

	if ig.IsControlPlane() {
		if len(ig.Spec.Subnets) == 0 {
			return nil, fmt.Errorf("control-plane InstanceGroup %s did not specify any Subnets", ig.ObjectMeta.Name)
		}
	} else if ig.IsAPIServerOnly() && cluster.Spec.IsIPv6Only() {
		if len(ig.Spec.Subnets) == 0 {
			for _, subnet := range cluster.Spec.Networking.Subnets {
				if subnet.Type != kops.SubnetTypePrivate && subnet.Type != kops.SubnetTypeUtility {
					ig.Spec.Subnets = append(ig.Spec.Subnets, subnet.Name)
				}
			}
		}
	} else {
		if len(ig.Spec.Subnets) == 0 {
			for _, subnet := range cluster.Spec.Networking.Subnets {
				if subnet.Type != kops.SubnetTypeDualStack && subnet.Type != kops.SubnetTypeUtility {
					ig.Spec.Subnets = append(ig.Spec.Subnets, subnet.Name)
				}
			}
		}

View on GitHub (pinned to 4c8573c808)

Solutions

1. Add spec.subnets to the control-plane InstanceGroup (e.g. [us-east-1a, us-east-1b] or dual-stack/IPv6 subnets as appropriate)
2. Pass --subnet when creating the group: `kops create instancegroup control-plane --role Master --subnet <name>`
3. Ensure the subnets referenced exist in cluster.spec.networking.subnets

Example fix

// before
metadata:
  name: control-plane-us-east-1a
spec:
  role: Master
// after
spec:
  role: Master
  subnets:
  - us-east-1a

// Ensure control-plane IG has subnets before calling kops
if ig.IsControlPlane() && len(ig.Spec.Subnets) == 0 {
    ig.Spec.Subnets = []string{"us-east-1a"} // pick from cluster.spec.networking.subnets
}
// or reject early:
if ig.IsControlPlane() && len(ig.Spec.Subnets) == 0 {
    return errors.New("control-plane instance group requires spec.subnets")
}

When it happens

Trigger: `kops create instancegroup` with role Master/control-plane and no --subnet flag; editing YAML to delete spec.subnets on a control-plane group; running `kops update cluster` after subnets were stripped from the IG manifest.

Common situations: Hand-writing control-plane InstanceGroup YAML and forgetting subnets; automated tooling regenerating IGs without carrying subnets over; migrating from older configs where subnet fields lived elsewhere.

Related errors

• error subnets must exist in the cluster
• error instance group cannot span public and private subnets
• must configure at least one ControlPlane InstanceGroup
• unable to infer any Subnets for InstanceGroup %s
• invalid InstanceGroup name: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/8376c9c1873ba4e7. Report an issue: GitHub.