code: def render_pulp_pull(self):
          
          # pulp_pull is a multi-phase plugin
          phases = ('postbuild_plugins', 'exit_plugins')
          plugin = 'pulp_pull'
          for phase in phases:
              if not self.dj.dock_json_has_plugin_conf(phase, plugin):
                  continue
  
              pulp_registry = self.spec.pulp_registry.value
              if not pulp_registry:
                  logger.info("removing %s from request, requires pulp_registry", pulp_registry)
                  self.dj.remove_plugin(phase, plugin)
                  continue
  
              if not self.spec.kojihub.value:
                  logger.info('Removing %s because no kojihub was specified', plugin)
                  self.dj.remove_plugin(phase, plugin)
                  continue
  
              if self.spec.prefer_schema1_digest.value is not None:
                  self.dj.dock_json_set_arg(phase, 'pulp_pull',
                                            'expect_v2schema2',
                                            not self.spec.prefer_schema1_digest.value)
docs: If a pulp registry is specified, use pulp_pull plugin