kubernetes/kops · error

error marshaling yaml: %v

Error message

error marshaling yaml: %v

What it means

When `kops toolbox dump` is run with -o yaml, the collected cloudResources are serialized with kops.ToRawYaml. This error indicates YAML marshaling of the in-memory dump structure failed, so no output was produced. It is rare and points to data that cannot be represented as the raw YAML map form.

Source

Thrown at cmd/kops/toolbox_dump.go:301

				klog.Warningf("error dumping resources: %v", err)
			}

			logDumper, err := dump.NewPodLogDumper(kubeConfig, options.Dir)
			if err != nil {
				return fmt.Errorf("error creating pod log dumper: %w", err)
			}
			if err := logDumper.DumpLogs(ctx); err != nil {
				klog.Warningf("error dumping pod logs: %v", err)
			}
		}
	}

	if cloudResources != nil {
		switch options.Output {
		case OutputYaml:
			b, err := kops.ToRawYaml(cloudResources)
			if err != nil {
				return fmt.Errorf("error marshaling yaml: %v", err)
			}
			_, err = out.Write(b)
			if err != nil {
				return fmt.Errorf("error writing to stdout: %v", err)
			}
			return nil

		case OutputJSON:
			b, err := json.MarshalIndent(cloudResources, "", "  ")
			if err != nil {
				return fmt.Errorf("error marshaling json: %v", err)
			}
			_, err = out.Write(b)
			if err != nil {
				return fmt.Errorf("error writing to stdout: %v", err)
			}
			return nil

View on GitHub (pinned to 4c8573c808)

Solutions

1. Retry with -o json to see if JSON marshaling works and isolate the issue
2. Update kops to the latest patch release
3. File an issue with the cluster/cloud provider details if it reproduces

Example fix

// before
b, err := kops.ToRawYaml(cloudResources)
if err != nil {
	return fmt.Errorf("error marshaling yaml: %v", err)
}
// after — fall back to JSON so the user still gets a dump
b, err := kops.ToRawYaml(cloudResources)
if err != nil {
	klog.Warningf("yaml marshal failed (%v); falling back to json", err)
	b, err = json.MarshalIndent(cloudResources, "", "  ")
	if err != nil {
		return fmt.Errorf("error marshaling json: %v", err)
	}
}

// No pre-call validation possible; data-dependent failure.
// Ensure cloudResources contains plain map/slice/scalar types before marshaling.

b, err := kops.ToRawYaml(cloudResources)
if err != nil {
	klog.Warningf("yaml marshal failed: %v", err)
	if b, jerr := json.MarshalIndent(cloudResources, "", "  "); jerr == nil {
		_, _ = out.Write(b)
		return nil
	}
	return fmt.Errorf("error marshaling yaml: %v", err)
}

When it happens

Trigger: Running `kops toolbox dump -o yaml` when ToRawYaml cannot convert the cloudResources value (unsupported/odd types produced by the dump, e.g. values that fail YAML conversion).

Common situations: Dumping clusters with unusual resource payloads; internal type changes after kops upgrades; custom output piping where the structure contains non-serializable values.

Related errors

• error writing yaml to stdout: %v
• unable to marshal YAML: %v
• unable to marshal YAML: %v
• unable to marshal YAML: %v
• error marshaling json: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/31a031c52bcc6454. Report an issue: GitHub.