kubernetes/kops · error

error doing mount %q: %v: %s

Error message

error doing mount %q: %v: %s

What it means

After option classification, execute runs the `mount <source> <mountpoint>` command (with -o for simple options). If the mount binary fails, the full argument list, error, and combined output are wrapped with this message. It means the kernel/sys mount of the source to the mountpoint failed.

Source

Thrown at upup/pkg/fi/nodeup/nodetasks/bindmount.go:225

			return fmt.Errorf("unknown option: %q", option)
		}
	}

	{
		args := []string{"mount"}
		if e.Recursive {
			args = append(args, "--rbind")
		} else {
			args = append(args, "--bind")
		}
		if len(simpleOptions) != 0 {
			args = append(args, "-o", strings.Join(simpleOptions, ","))
		}
		args = append(args, e.Source, e.Mountpoint)

		klog.Infof("running mount command %s", args)
		if output, err := t.CombinedOutput(args); err != nil {
			return fmt.Errorf("error doing mount %q: %v: %s", strings.Join(args, " "), err, string(output))
		}
	}

	if len(remountOptions) != 0 {
		args := []string{"mount", "-o", "remount," + strings.Join(remountOptions, ","), e.Mountpoint}

		klog.Infof("running mount command %s", args)
		if output, err := t.CombinedOutput(args); err != nil {
			return fmt.Errorf("error doing mount options %q: %v: %s", strings.Join(args, " "), err, string(output))
		}
	}

	if len(makeOptions) != 0 {
		args := []string{"mount"}
		args = append(args, makeOptions...)
		args = append(args, e.Mountpoint)

		klog.Infof("running mount command %s", args)

View on GitHub (pinned to 4c8573c808)

Solutions

1. Read the wrapped mount output for the kernel's errno (e.g. "No such file or directory", "already mounted") and fix accordingly
2. Ensure the mountpoint directory exists and the source path/device is present before nodeup runs
3. Verify nodeup runs as root with CAP_SYS_ADMIN (host systemd unit, privileged container)
4. Check `mount | grep <mountpoint>` for an existing conflicting mount

if _, err := os.Stat(source); err != nil { return fmt.Errorf("bindmount source missing: %w", err) }
if _, err := os.Stat(mountpoint); err != nil {
  if err := os.MkdirAll(mountpoint, 0o755); err != nil { return err }
}
if mounted, _ := isMounted(mountpoint); mounted { return errors.New("already mounted") }

out, err := t.CombinedOutput(args)
if err != nil {
  return fmt.Errorf("error doing mount %q: %v: %s", strings.Join(args, " "), err, string(out))
}
// inspect output for errno: EBUSY -> already mounted, ENOENT -> create paths, EPERM -> privileges

When it happens

Trigger: t.CombinedOutput on `mount` returns non-zero — source path doesn't exist, mountpoint missing, already mounted, unsupported filesystem, or insufficient privileges (not root / missing CAP_SYS_ADMIN).

Common situations: Missing mountpoint directory; source device/directory not yet provisioned; EBUSY on double mount; running nodeup without root in a container.

Related errors

• error doing mount options %q: %v: %s
• failed to create bpf mount unit: %w
• failed to create cgroupv2 mount unit: %w
• failed to ensure the directory: %s, error: %w
• failed to check if device %q is mounted, error: %w

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/e2ff6685218c239a. Report an issue: GitHub.