What causes "error getting random bytes" in hyperledger/fabric?

Ensure /dev/urandom is accessible in the container/host and not blocked by seccomp or device cgroup rules

error getting random bytes

Error message

error getting random bytes

What it means

getRandomNonce reads 24 cryptographically random bytes via crypto/rand; this error wraps any failure of rand.Read. It is a system-level failure (entropy source unavailable) surfaced whenever a nonce is created for a proposal or txid.

Source

Thrown at protoutil/commonutils.go:287

}

// EnvelopeToConfigUpdate is used to extract a ConfigUpdateEnvelope from an envelope of
// type CONFIG_UPDATE
func EnvelopeToConfigUpdate(configtx *cb.Envelope) (*cb.ConfigUpdateEnvelope, error) {
	configUpdateEnv := &cb.ConfigUpdateEnvelope{}
	_, err := UnmarshalEnvelopeOfType(configtx, cb.HeaderType_CONFIG_UPDATE, configUpdateEnv)
	if err != nil {
		return nil, err
	}
	return configUpdateEnv, nil
}

func getRandomNonce() ([]byte, error) {
	key := make([]byte, 24)

	_, err := rand.Read(key)
	if err != nil {
		return nil, errors.Wrap(err, "error getting random bytes")
	}
	return key, nil
}

func IsConfigTransaction(envelope *cb.Envelope) bool {
	payload, err := UnmarshalPayload(envelope.Payload)
	if err != nil {
		return false
	}

	if payload.Header == nil {
		return false
	}

	hdr, err := UnmarshalChannelHeader(payload.Header.ChannelHeader)
	if err != nil {
		return false
	}

View on GitHub (pinned to 2736b63f8f)

Solutions

Ensure /dev/urandom is accessible in the container/host and not blocked by seccomp or device cgroup rules
Check kernel entropy health (dmesg for random: messages); add haveged/rngd only on legacy kernels
Retry the operation — crypto/rand failures are usually transient or environmental
If inside a custom sandbox, verify getrandom(2) syscall is permitted

Defensive patterns

Strategy: retry

Validate before calling

// No caller-side pre-check possible; verify entropy source availability instead:
// In deployment: test `head -c 24 /dev/urandom > /dev/null` works in the container.
if _, err := os.Stat("/dev/urandom"); err != nil {
	return fmt.Errorf("entropy source unavailable: %w", err)
}

Try / catch

nonce, err := protoutil.CreateNonce()
if err != nil {
	if strings.Contains(err.Error(), "random bytes") {
		// transient/environmental: back off and retry
		time.Sleep(backoff)
		nonce, err = protoutil.CreateNonce()
	}
	if err != nil { return fmt.Errorf("entropy failure, check /dev/urandom and seccomp profile: %w", err) }
}

Prevention

Ensure /dev/urandom is mounted and permitted in containers (devices cgroup, seccomp allow getrandom)
Avoid minimal runtimes that block crypto/rand syscalls
Alert on this error — it signals host-level entropy problems, not app bugs

When it happens

Trigger: Indirectly triggered via CreateNonce, CreateChaincodeProposalWithTransient/WithTxIDAndTransient, or CreateProposalFromCISAndTxid when crypto/rand.Read fails — e.g. entropy pool exhausted, or running in a container/sandbox where /dev/urandom is unavailable or blocked.

Common situations: Containers with restricted /dev/urandom access; seccomp/AppArmor profiles blocking getrandom(2); extremely low-entropy environments (rare on modern Linux); VMs without a hardware RNG early in boot.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/a3d018f77a282a05. Report an issue: GitHub.