kubernetes/kops · error

error writing secret to %q: %v

Error message

error writing secret to %q: %v

What it means

This error is returned by ClientsetSecretStore.MirrorTo when the vfs.Path.WriteFile call fails after the secret has been successfully serialized. It wraps the underlying storage-layer error (S3/GS/swift/file etc.), so the root cause is in the wrapped %v text. It means the secret bytes could not be persisted to the backing store at the given path.

Source

Thrown at upup/pkg/fi/secrets/clientset_secretstore.go:95

		name := strings.TrimPrefix(keyset.Name, NamePrefix)
		p := BuildVfsSecretPath(basedir, name)

		s := &fi.Secret{
			Data: primary.PrivateMaterial,
		}
		data, err := json.Marshal(s)
		if err != nil {
			return fmt.Errorf("error serializing secret: %v", err)
		}

		acl, err := acls.GetACL(ctx, p, c.cluster)
		if err != nil {
			return err
		}

		if err := p.WriteFile(ctx, bytes.NewReader(data), acl); err != nil {
			return fmt.Errorf("error writing secret to %q: %v", p, err)
		}
	}

	return nil
}

// FindSecret implements fi.SecretStore::FindSecret
func (c *ClientsetSecretStore) FindSecret(name string) (*fi.Secret, error) {
	ctx := context.TODO()

	s, err := c.loadSecret(ctx, name)
	if err != nil {
		return nil, err
	}
	return s, nil
}

// ListSecrets implements fi.SecretStore::ListSecrets

View on GitHub (pinned to 4c8573c808)

Solutions

1. Read the wrapped error after %v to find the storage-layer root cause
2. Verify the state store path (--state) points to an existing, writable location
3. Check cloud IAM credentials/permissions allow writing to the secret path (e.g. s3:PutObject on the cluster prefix)
4. Confirm network connectivity/VPN to the storage endpoint and retry
5. Verify the ACL returned by acls.GetACL matches the backend's permission model

Example fix

// before: blind retry hides transient cause
if err := p.WriteFile(ctx, bytes.NewReader(data), acl); err != nil {
    return fmt.Errorf("error writing secret to %q: %v", p, err)
}
// after: retry transient storage failures
if err := p.WriteFile(ctx, bytes.NewReader(data), acl); err != nil {
    return fmt.Errorf("error writing secret to %q: %v", p, err)
}
// caller side:
if err := store.MirrorTo(ctx, basedir); err != nil {
    if isTransient(err) { time.Sleep(retryBackoff); err = store.MirrorTo(ctx, basedir) }
    if err != nil { return err }
}

// verify the VFS destination is writable before mirroring
func writable(p vfs.Path) error {
    acl, err := acls.GetACL(context.TODO(), p, cluster)
    if err != nil { return err }
    probe := BuildVfsSecretPath(p, ".write-probe")
    if err := probe.WriteFile(context.TODO(), bytes.NewReader([]byte{}), acl); err != nil {
        return fmt.Errorf("state store not writable: %v", err)
    }
    return probe.Remove(context.TODO())
}

func isVFSWriteError(err error) bool {
    return err != nil && strings.Contains(err.Error(), "error writing secret to")
}

err := store.MirrorTo(ctx, basedir)
if err != nil && isVFSWriteError(err) {
    for i := 0; i < 3; i++ {
        time.Sleep(time.Duration(1<<i) * time.Second)
        if err = store.MirrorTo(ctx, basedir); err == nil { break }
    }
}
if err != nil { return err }

When it happens

Trigger: During MirrorTo, after GetACL succeeds, p.WriteFile(ctx, bytes.NewReader(data), acl) returns an error — network failure, missing bucket/container, insufficient IAM permissions, or ACL mismatch on the VFS path for the cluster.

Common situations: Cloud credentials missing or expired during `kops toolbox dump`/secret mirroring; S3 bucket deleted or wrong --state store configured; IAM policy lacking s3:PutObject; read-only state store; transient network outage.

Related errors

• reading file: %w
• reading tree: %w
• error listing secrets for mirror: %v
• error listing secrets directory: %v
• error reading directory %q: %v

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/f05100d64b95eed4. Report an issue: GitHub.