kubernetes/kops · error

failed to consistently write file %q - too many retries

Error message

failed to consistently write file %q - too many retries

What it means

The pseudo-atomic writer exhausted its retry budget: every write to /etc/hosts was overwritten by another process before the verification re-read, so the guarded block could never be committed consistently.

Source

Thrown at pkg/dns/hosts/hosts.go:213

		return fmt.Errorf("error writing file %q: %v", p, err)
	}

	return nil
}

// Because we are bind-mounting /etc/hosts, we can't do a normal
// atomic file write (where we write a temp file and rename it);
// instead we write the file, pause, re-read and see if anyone else
// wrote in the meantime; if so we rewrite again.  By pausing for a
// random amount of time, eventually we'll win the write race and
// exit.  This doesn't guarantee fairness, but it should mean that the
// end-result is not malformed (i.e. partial writes).
func pseudoAtomicWrite(p string, b []byte, mode os.FileMode) error {
	attempt := 0
	for {
		attempt++
		if attempt > 10 {
			return fmt.Errorf("failed to consistently write file %q - too many retries", p)
		}

		if err := os.WriteFile(p, b, mode); err != nil {
			klog.Warningf("error writing file %q: %v", p, err)
			continue
		}

		n := 1 + math_rand.Intn(20)
		time.Sleep(time.Duration(n) * time.Millisecond)

		contents, err := os.ReadFile(p)
		if err != nil {
			klog.Warningf("error re-reading file %q: %v", p, err)
			continue
		}

		if bytes.Equal(contents, b) {
			return nil

View on GitHub (pinned to 4c8573c808)

Solutions

1. Identify the competing writer (other containers or system daemons writing /etc/hosts) and serialize updates
2. Retry at a quieter moment; the random-backoff loop wins eventually
3. Reduce concurrent processes mutating hosts entries on the node

When it happens

Trigger: Thrown at pkg/dns/hosts/hosts.go:213 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/51b298604eba9726. Report an issue: GitHub.