kubernetes/kops · error

instanceGroup cannot be nil

Error message

instanceGroup cannot be nil

What it means

BuildConfig requires a non-nil InstanceGroup to generate the NodeUp config. Passing nil means the caller lost track of which instance group the node belongs to, so role-specific config (control-plane vs node) cannot be produced.

Source

Thrown at pkg/nodemodel/nodeupconfigbuilder.go:180

	configBuilder := nodeUpConfigBuilder{
		assetBuilder:               assetBuilder,
		channelsManifest:           channelsManifest,
		configBase:                 configBase,
		cluster:                    cluster,
		etcdManifests:              etcdManifests,
		images:                     images,
		encryptionConfigSecretHash: encryptionConfigSecretHash,
	}

	return &configBuilder, nil
}

// BuildConfig returns the NodeUp config and auxiliary config.
func (n *nodeUpConfigBuilder) BuildConfig(ig *kops.InstanceGroup, wellKnownAddresses model.WellKnownAddresses, keysets map[string]*fi.Keyset) (*nodeup.Config, *nodeup.BootConfig, error) {
	cluster := n.cluster

	if ig == nil {
		return nil, nil, fmt.Errorf("instanceGroup cannot be nil")
	}

	role := ig.Spec.Role
	if role == "" {
		return nil, nil, fmt.Errorf("cannot determine role for instance group: %v", ig.ObjectMeta.Name)
	}

	isMaster := role.HasControlPlane()
	hasAPIServer := isMaster || role.HasAPIServer()

	config, bootConfig := nodeup.NewConfig(cluster, ig)

	igModel, err := kopsmodel.ForInstanceGroup(cluster, ig)
	if err != nil {
		return nil, nil, fmt.Errorf("building instance group model: %w", err)
	}

	if !hasAPIServer && n.assetBuilder.KubeletSupportedVersion != "" {

View on GitHub (pinned to 4c8573c808)

Solutions

1. Ensure the InstanceGroup is resolved for the node before calling BuildConfig
2. Check that the node's InstanceGroup lookup (by node labels/name) succeeds — an unmatched node usually indicates the IG was deleted or renamed
3. Pass the correct *kops.InstanceGroup from the caller (e.g. from nodeup bootstrap data) instead of nil

Example fix

// before
config, _, err := builder.BuildConfig(nil, addresses, keysets)
// after
ig, err := findInstanceGroup(nodeName)
if err != nil { return err }
config, _, err := builder.BuildConfig(ig, addresses, keysets)

if ig == nil {
    return fmt.Errorf("refusing BuildConfig: instance group unresolved for node")
}

func igResolved(ig *kops.InstanceGroup) bool { return ig != nil }

When it happens

Trigger: BuildConfig called with ig == nil, e.g. when nodeup model building fails to map a node/instance to its InstanceGroup before building config.

Common situations: Node not associated with any instance group; a nil IG passed from the nodeup bootstrap path due to lookup failure; programmatic callers of BuildConfig with uninitialized variable.

Related errors

• cannot determine role for instance group: %v
• building instance group model: %w
• did not find owner for node %q
• invalid InstanceGroup name: %v
• error building InstanceGroup from CAPI Machine: %w

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/e77c893ed79b059d. Report an issue: GitHub.