code: def _yarn_init(self, rm_address, requests_config, tags):
          
          running_apps = self._yarn_get_running_spark_apps(rm_address, requests_config, tags)
  
          # Report success after gathering all metrics from ResourceManager
          self.service_check(
              YARN_SERVICE_CHECK,
              AgentCheck.OK,
              tags=['url:%s' % rm_address] + tags,
              message='Connection to ResourceManager "%s" was successful' % rm_address,
          )
  
          return running_apps
docs: Return a dictionary of {app_id: (app_name, tracking_url)} for running Spark applications.