kubernetes/kops · error

error generating random label suffix: %w

Error message

error generating random label suffix: %w

What it means

buildLinodeInstanceLabel appends a random hex suffix to the group name to create a unique Linode label. This wraps a failure reading random bytes from crypto/rand, without which no unique label can be produced.

Source

Thrown at upup/pkg/fi/cloudup/linodetasks/instance.go:321

	var interfaces []linodego.LinodeInterfaceCreateOptions
	if requirePublicInterface {
		interfaces = append(interfaces, linodego.LinodeInterfaceCreateOptions{
			Public: &linodego.PublicInterfaceCreateOptions{},
		})
	}
	interfaces = append(interfaces, linodego.LinodeInterfaceCreateOptions{
		VPC: &linodego.VPCInterfaceCreateOptions{SubnetID: subnetID},
	})

	return interfaces
}

// buildLinodeInstanceLabel generates a unique label for the Akamai (Linode) instance by appending a random suffix to the provided name.
// It ensures that the final label does not exceed 64 characters and trims any trailing hyphens, underscores, or periods.
func buildLinodeInstanceLabel(name string) (string, error) {
	var randomSuffix [8]byte
	if _, err := cryptorand.Read(randomSuffix[:]); err != nil {
		return "", fmt.Errorf("error generating random label suffix: %w", err)
	}

	suffix := fmt.Sprintf("-%x", randomSuffix)
	maxBaseLength := 64 - len(suffix)
	if len(name) > maxBaseLength {
		name = name[:maxBaseLength]
	}
	name = strings.TrimRight(name, "-_.")

	return name + suffix, nil
}

// hasExpectedInterfaces checks if the Akamai (Linode) instance has the expected network interfaces.
// It verifies that there is exactly one VPC interface with the matching subnet ID and checks for the presence of a public interface if required.
func hasExpectedInterfaces(interfaces []linodego.LinodeInterface, subnetID int, requirePublicInterface bool) bool {
	publicCount := 0
	vpcCount := 0
	hasMatchingVPCSubnet := false

View on GitHub (pinned to 4c8573c808)

Solutions

1. Restore access to /dev/urandom on the host
2. Re-run kops update after fixing entropy
3. Move the operation to a host without entropy restrictions

label, err := buildLinodeInstanceLabel(name)
if err != nil {
    // check host entropy; abort or fall back to a deterministic suffix
    return "", fmt.Errorf("error generating random label suffix: %w", err)
}

When it happens

Trigger: cryptorand.Read fails on the host (broken/limited entropy source) while generating the 8-byte suffix during instance creation.

Common situations: Running kops in a sandboxed container without /dev/urandom access, or a kernel with severely constrained entropy.

Related errors

• error generating Akamai (Linode) instance label for group %q
• error getting random data: %w
• error building linode node identifier: %w
• error disabling swap: %v
• failed to read %s: %w

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/6c594c5b128894ca. Report an issue: GitHub.