code: def run(self):
          
          if self.workflow.builder.base_from_scratch and not self.workflow.builder.parent_images:
              self.log.info("Skipping add yum repo by url: unsupported for FROM-scratch images")
              return
  
          if self.repourls:
              for repourl in self.repourls:
                  yumrepo = YumRepo(repourl)
                  self.log.info("fetching yum repo from '%s'", yumrepo.repourl)
                  try:
                      yumrepo.fetch()
                  except Exception as e:
                      msg = "Failed to fetch yum repo {repo}: {exc}".format(
                          repo=yumrepo.repourl, exc=e)
                      raise RuntimeError(msg)
                  else:
                      self.log.info("fetched yum repo from '%s'", yumrepo.repourl)
  
                  if self.inject_proxy:
                      if yumrepo.is_valid():
                          yumrepo.set_proxy_for_all_repos(self.inject_proxy)
                  self.workflow.files[yumrepo.dst_filename] = yumrepo.content
                  self.log.debug("saving yum repo '%s', length %d", yumrepo.dst_filename,
                                 len(yumrepo.content))
docs: run the plugin