code: async def setup_hostname() -> str:
      
      machine_id = open('/etc/machine-id').read().strip()
      hostname = machine_id[:6]
      with open('/etc/hostname', 'w') as ehn:
          ehn.write(f'{hostname}\n')
  
      # First, we run hostnamed which will set the transient hostname
      # and loaded static hostname from the value we just wrote to
      # /etc/hostname
      LOG.debug("Setting hostname")
      proc = await asyncio.create_subprocess_exec(
          'hostname', '-F', '/etc/hostname',
          stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE)
      stdout, stderr = await proc.communicate()
      ret = proc.returncode
      if ret != 0:
          LOG.error(
              f'Error starting hostname: {ret} '
              f'stdout: {stdout} stderr: {stderr}')
          raise RuntimeError("Couldn't run hostname")
  
      # Then, with the hostname set, we can restart avahi
      LOG.debug("Restarting avahi")
      proc = await asyncio.create_subprocess_exec(
          'systemctl', 'restart', 'avahi-daemon',
          stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE)
      stdout, stderr = await proc.communicate()
      ret = proc.returncode
      if ret != 0:
          LOG.error(
              f'Error restarting avahi-daemon: {ret} '
              f'stdout: {stdout} stderr: {stderr}')
          raise RuntimeError("Error restarting avahi")
      LOG.debug("Updated hostname and restarted avahi OK")
      return hostname
docs: Intended to be run when the server starts. Sets the machine hostname.
  
      The machine hostname is set from the systemd-generated machine-id, which
      changes at every boot.
  
      Once the hostname is set, we restart avahi.
  
      This is a separate task from establishing and changing the opentrons
      machine name, which is UTF-8 and stored in /etc/machine-info as the
      PRETTY_HOSTNAME and used in the avahi service name.
  
      :returns: the hostname