kubernetes/kops · error

no subnets found in cluster %q

Error message

no subnets found in cluster %q

What it means

When auto-selecting a subnet for the MachineDeployment, the command collects cluster.Spec.Networking.Subnets into a set; if the set is empty it returns 'no subnets found in cluster %q'. A cluster spec with no subnets cannot host worker machines.

Source

Thrown at pkg/commands/toolbox/clusterapi/generate_machinedeployment.go:123

	if err != nil {
		return err
	}

	cluster, err := clientset.GetCluster(ctx, options.ClusterName)
	if err != nil {
		return err
	}

	// TODO: Sync with LinkToSubnet and support ID
	subnet := options.Subnet
	if subnet == "" {
		subnets := sets.New[string]()
		for _, subnet := range cluster.Spec.Networking.Subnets {
			subnets.Insert(subnet.Name)
		}

		if subnets.Len() == 0 {
			return fmt.Errorf("no subnets found in cluster %q", options.ClusterName)
		}
		if subnets.Len() > 1 {
			klog.Warningf("multiple subnets found in cluster %q; using an arbitrary subnet", options.ClusterName)
		}
		subnet = sets.List(subnets)[0]
		log.Info("selected subnet", "subnet", subnet)
	}

	zones := options.Zones

	// TODO: When to use cluster zones, when to use IG zones?
	// if zone == "" {
	// 	for _, subnetCandidate := range cluster.Spec.Networking.Subnets {
	// 		if subnetCandidate.Name == subnet {
	// 			zone = subnetCandidate.Zone
	// 		}
	// 	}
	// 	if zone == "" {

View on GitHub (pinned to 4c8573c808)

Solutions

1. Add subnets to the cluster spec: `kops edit cluster` and define subnets under spec.networking.subnets, then `kops update cluster`.
2. Re-run `kops create cluster` with valid --zones so subnets are generated.
3. Verify with `kops get cluster -oyaml | grep -A5 subnets` that subnets exist before generating.

Example fix

// before: cluster spec
networking:
  subnets: []
// after: kops edit cluster
networking:
  subnets:
  - name: us-east-1a
    type: Public
    zone: us-east-1a

cluster, err := clientset.GetCluster(ctx, options.ClusterName)
if err != nil { return err }
if cluster.Spec.Networking == nil || len(cluster.Spec.Networking.Subnets) == 0 {
	return fmt.Errorf("cluster %q has no subnets; run kops edit cluster first", options.ClusterName)
}

func clusterHasSubnets(c *api.Cluster) bool {
	return c != nil && c.Spec.Networking != nil && len(c.Spec.Networking.Subnets) > 0
}

if err := RunGenerateMachineDeployment(ctx, f, out, options); err != nil {
	if strings.Contains(err.Error(), "no subnets found in cluster") {
		return fmt.Errorf("fix cluster spec (add spec.networking.subnets) then retry: %w", err)
	}
	return err
}

When it happens

Trigger: Generating a MachineDeployment for a cluster whose spec has an empty Spec.Networking.Subnets list — e.g. a partially created or hand-edited cluster config, or a spec that failed population.

Common situations: Manually stripped subnets in `kops edit cluster`; clusters created from incomplete templates; spec fetched from a statestore before initial update populated networking.

Related errors

• found multiple subnets with name: %q
• error creating kops config template: %w
• error creating gcp machine template: %w
• error building machine deployments: %w
• configuration must include Subnets

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/4ebe9723cfc757e6. Report an issue: GitHub.