private String extractImageID(final String leaseDescription) {
    assert leaseDescription.startsWith("api services lease granted by ");
    String currentImageID = leaseDescription.substring(30);
    final int firstSpaceIndex = currentImageID.indexOf(" ");
    if (firstSpaceIndex > 0) {
      currentImageID = currentImageID.substring(0, firstSpaceIndex);
    }
    return currentImageID;
  }