kubernetes/kops · error

error marshaling kubeconfig to yaml: %v

Error message

error marshaling kubeconfig to yaml: %v

What it means

The kubeconfig task builds an in-memory service-account kubeconfig and serializes it with kops.ToRawYaml; a marshal failure is wrapped here. Since the config is plain maps/slices, this almost always means a value type YAML cannot represent (e.g. func, chan, or unmarshalable type leaked into the config struct).

Source

Thrown at upup/pkg/fi/nodeup/nodetasks/kubeconfig.go:127

				Name:    "local",
				Cluster: cluster,
			},
		},
		Contexts: []*kubeconfig.KubectlContextWithName{
			{
				Name: "service-account-context",
				Context: kubeconfig.KubectlContext{
					Cluster: "local",
					User:    k.Name,
				},
			},
		},
		CurrentContext: "service-account-context",
	}

	yaml, err := kops.ToRawYaml(config)
	if err != nil {
		return fmt.Errorf("error marshaling kubeconfig to yaml: %v", err)
	}

	output := k.GetConfig()
	output.Resource = fi.NewBytesResource(yaml)

	return nil
}

View on GitHub (pinned to 4c8573c808)

Solutions

1. Inspect the wrapped %v error for the offending field/type
2. Ensure all fields of the kubeconfig struct are YAML-serializable (strings, ints, maps, slices)
3. Test ToRawYaml on the constructed config in a unit test to reproduce
4. Use the stock nodeup binary matching your kOps version rather than a patched one

Example fix

// before
config.Users[0].Exec = someFunc // non-serializable
// after
config.Users[0].Exec = map[string]interface{}{"command": "..."}

// ensure the config only holds YAML-safe types before marshaling
if err := yaml.Unmarshal([]byte("{}"), &config); err != nil { /* struct shape ok */ }

yamlBytes, err := kops.ToRawYaml(config)
if err != nil {
  return fmt.Errorf("building service-account kubeconfig failed: %w", err)
}

When it happens

Trigger: Run() of the kubeconfig task calls kops.ToRawYaml(config) and it returns an error while producing the service-account kubeconfig.

Common situations: Code change introduced a non-serializable field into the kubeconfig struct; customized nodeup build passing unexpected types; nil vs typed mismatch in map values.

Related errors

• parsing kops-channels manifest: %w
• converting kubeconfig to yaml: %w
• error converting nodeup config to yaml: %v
• error converting boot config to yaml: %w
• error parsing configuration %q: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/c4f3b28f2efd6508. Report an issue: GitHub.