kubernetes/kops · error

unable to determine default image for instance group %q: %v

Error message

unable to determine default image for instance group %q: %v

What it means

After resolving the architecture, kOps calls defaultImage(cluster, channel, architecture) to select the base image for the InstanceGroup. This error wraps a failure there — no suitable default image exists in the channel for that architecture/cloud.

Source

Thrown at upup/pkg/fi/cloudup/populate_instancegroup_spec.go:156

		}
		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)
		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)
		}

View on GitHub (pinned to 4c8573c808)

Solutions

1. Set spec.image explicitly in the InstanceGroup
2. Update kOps (newer releases ship updated channels with fresh AMIs/images)
3. Verify the channel source is reachable and correct (`kops get cluster` shows the channel in use)
4. Check the wrapped error: if it mentions architecture, ensure the channel supports it or change machine architecture

Example fix

// before
spec:
  role: Node
// after
spec:
  role: Node
  image: 099720109477/ubuntu/images/hvm-ssd/ubuntu-jammy-22.04-amd64-server-20240207.1

// Pre-check that an image is configured or channel supports the arch
if ig.Spec.Image == "" && (cluster.Spec.Channel == nil || cluster.GetKubernetesVersion() == "") {
    return errors.New("no image set and channel defaults unavailable; set spec.image")
}

When it happens

Trigger: Creating a cluster/InstanceGroup with spec.image empty while the kOps channel has no default image entry for the resolved architecture, or the channel file is missing/outdated/unparseable.

Common situations: Using an old kOps binary whose bundled channel lacks current images (cloud provider retired old images); unusual architecture (arm64) with an old channel; offline/air-gapped environments where image sources are unreachable; malformed --channel URL.

Related errors

• error loading channel %q: %v
• invalid base channel location: %q
• error reading channel %q: %v
• error parsing channel %q: %v
• error parsing channel %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/c21d3f6f4cfb2d06. Report an issue: GitHub.