code: def get_bootstrap_osd_key(cluster):
      
      path = '{cluster}.bootstrap-osd.keyring'.format(cluster=cluster)
      try:
          with open(path, 'rb') as f:
              return f.read()
      except IOError:
          raise RuntimeError('bootstrap-osd keyring not found; run \'gatherkeys\'')
docs: Read the bootstrap-osd key for `cluster`.