kubernetes/kops · error

error reading ' ' on config drive

Error message

error reading '%s' on config drive: %v

What it means

Once the config drive is mounted, getFromConfigDrive (upup/pkg/fi/cloudup/openstack/openstackmetadata/metadata.go:128) opens the metadata JSON file at mds.configDrivePath inside the mount. If os.Open fails (file missing, wrong path, unreadable filesystem), this error naming the path is returned.

Solutions

1. Verify the expected file exists on the mounted drive: `ls <mountTarget>/<configDrivePath>`; adjust configDrivePath if your cloud lays files out differently.
2. Regenerate the instance with a standard config drive (nova boot --config-drive true).
3. Check the config-drive image integrity (e.g. `isoinfo -l -i <dev>`) and that the correct device was mounted.
4. Confirm file permissions allow the reading user (root) to open the file.

Example fix

// before
f, err := os.Open(path.Join(mds.mountTarget, mds.configDrivePath))
if err != nil {
    return nil, fmt.Errorf("error reading '%s' on config drive: %v", mds.configDrivePath, err)
}
// after — check the file exists first for a clearer diagnosis
metaPath := path.Join(mds.mountTarget, mds.configDrivePath)
if _, err := os.Stat(metaPath); os.IsNotExist(err) {
    return nil, fmt.Errorf("config drive mounted but %s is missing; wrong drive or layout", metaPath)
}
f, err := os.Open(metaPath)

// After mounting, verify the expected metadata file exists before opening it
metaPath := filepath.Join("/mnt/config-drive", "openstack/latest/meta_data.json")
if fi, err := os.Stat(metaPath); err != nil || fi.IsDir() {
    return fmt.Errorf("expected metadata file %s not present on config drive", metaPath)
}

meta, err := mds.getFromConfigDrive()
if err != nil {
    var pathErr *fs.PathError
    if errors.As(err, &pathErr) && strings.Contains(err.Error(), "on config drive") {
        // wrong layout or wrong device — fall back to the metadata service
        return mds.getFromMetadataService()
    }
    return nil, err
}

When it happens

Trigger: os.Open(path.Join(mds.mountTarget, mds.configDrivePath)) fails — the expected file (e.g. openstack/latest/meta_data.json) is absent from the config drive, the drive content layout differs from the expected path, or the mount succeeded but the filesystem is unreadable/corrupt.

Common situations: Config drive produced by a tool that lays out files differently than the expected configDrivePath; truncated or corrupted config-drive image; mounting the wrong device as the config drive; permission problems on the mounted filesystem.

Related errors

• error mounting configdrive
• unable to run blkid
• error getting cloud instance group
• error parsing etcd cluster tag
• failed to get info for server

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/bc5ba9053c6b9e44. Report an issue: GitHub.

Appendix: source

Thrown at upup/pkg/fi/cloudup/openstack/openstackmetadata/metadata.go:128

		if err != nil {
			return nil, fmt.Errorf("unable to run blkid: %v", err)
		}
		dev = strings.TrimSpace(string(out))
	}

	err := mds.mounter.Mount(dev, mds.mountTarget, "iso9660", []string{"ro"})
	if err != nil {
		err = mds.mounter.Mount(dev, mds.mountTarget, "vfat", []string{"ro"})
	}
	if err != nil {
		return nil, fmt.Errorf("error mounting configdrive '%s': %v", dev, err)
	}
	defer mds.mounter.Unmount(mds.mountTarget)

	f, err := os.Open(
		path.Join(mds.mountTarget, mds.configDrivePath))
	if err != nil {
		return nil, fmt.Errorf("error reading '%s' on config drive: %v", mds.configDrivePath, err)
	}
	defer f.Close()

	return mds.parseMetadata(f)
}

// getFromMetadataService tries to get metadata from a metadata service endpoint and returns it as InstanceMetadata.
// If the service endpoint cannot be contacted or reports a different status than StatusOK it will return an error.
func (mds MetadataService) getFromMetadataService() (*InstanceMetadata, error) {
	var client http.Client

	resp, err := client.Get(mds.serviceURL)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusOK {

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