What causes "cannot interpret %q value as v1.Duration" in kubernetes/kops?

Use time.ParseDuration syntax with units: "300s", "5m", "1h30m"

cannot interpret %q value as v1.Duration

Error message

cannot interpret %q value as v1.Duration

What it means

When a field is tagged as metav1.Duration ("v1.Duration"), setType parses the string with time.ParseDuration. Any string that is not a Go duration literal (e.g. missing unit) produces this error. It tells you the supplied value is not a valid duration for the field.

Source

Thrown at util/pkg/reflectutils/access.go:281

		fdName, found := envVarType.FieldByName("Name")
		if !found {
			return fmt.Errorf("field Name not found in %T", newV.Interface())
		}
		fdValue, found := envVarType.FieldByName("Value")
		if !found {
			return fmt.Errorf("field Value not found in %T", newV.Interface())
		}

		name, value, hasValue := strings.Cut(newValue, "=")
		newV.FieldByIndex(fdName.Index).SetString(name)
		if hasValue {
			newV.FieldByIndex(fdValue.Index).SetString(value)
		}

	case "v1.Duration":
		duration, err := time.ParseDuration(newValue)
		if err != nil {
			return fmt.Errorf("cannot interpret %q value as v1.Duration", newValue)
		}
		newV = reflect.ValueOf(metav1.Duration{Duration: duration})

	case "resource.Quantity":
		quantity, err := resource.ParseQuantity(newValue)
		if err != nil {
			return fmt.Errorf("cannot interpret %q value as resource.Quantity", newValue)
		}
		newV = reflect.ValueOf(quantity)

	default:
		// This handles enums and other simple conversions
		newV = reflect.ValueOf(newValue)
		if newV.Type().ConvertibleTo(v.Type()) {
			newV = newV.Convert(v.Type())
		} else {
			return fmt.Errorf("unhandled type %q", t)
		}

View on GitHub (pinned to 4c8573c808)

Solutions

Use time.ParseDuration syntax with units: "300s", "5m", "1h30m"
For a plain seconds number, check whether the field is actually an int and pass 300 instead of "300s"
Validate the value locally with `go` time.ParseDuration before running the set command

Example fix

// before
kops set cluster spec.kubelet.evictionHard="nodefs.available<10"
// duration example before
kops set ... spec.nodeProblemDetector.monitorPeriod=30
// after
kops set ... spec.nodeProblemDetector.monitorPeriod=30s

Defensive patterns

Strategy: validation

Validate before calling

d := "30s"
if _, err := time.ParseDuration(d); err != nil {
	return fmt.Errorf("invalid duration %q: %v", d, err)
}

Type guard

func isValidDuration(s string) bool { _, err := time.ParseDuration(s); return err == nil }

Try / catch

if err := doSet(); err != nil && strings.Contains(err.Error(), "as v1.Duration") {
	// retry with corrected duration string, e.g. append "s"
}

Prevention

Always include a time unit (s/m/h) in duration values
Validate durations with time.ParseDuration before applying
Remember these are Go durations, not plain seconds

When it happens

Trigger: `kops set cluster spec.kubelet.nodeLeaseDurationSeconds=5m` style calls on duration-tagged fields (e.g. kube-dns, node-problem-detector settings) with strings like "300", "5", or "forever" — time.ParseDuration requires a unit.

Common situations: Users copy seconds values from Kubernetes docs into duration fields, forgetting Go duration syntax; empty values from templates; locale-specific formats like "1h30" (missing m).

Understand the failure class

Background: "invalid duration" / "failed to parse duration": why your timeout, interval, or TTL string is rejected and which formats each library accepts — this error's family across 32 libraries.

Related errors

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/1ebb0e74136b6796. Report an issue: GitHub.