code: def update_hosts_file_from_port_spec(port_spec):
      
      logging.info('Updating hosts file to match port spec')
      hosts_specs = port_spec['hosts_file']
      current_hosts = config_file.read(constants.HOSTS_PATH)
      cleared_hosts = config_file.remove_current_dusty_config(current_hosts)
      updated_hosts = cleared_hosts + _dusty_hosts_config(hosts_specs)
      config_file.write(constants.HOSTS_PATH, updated_hosts)
docs: Given a port spec, update the hosts file specified at
      constants.HOST_PATH to contain the port mappings specified
      in the spec. Any existing Dusty configurations are replaced.