text: import json
  import os
  
  from mlflow.entities import FileInfo
  from mlflow.exceptions import IllegalArtifactPathError, MlflowException
  from mlflow.store.artifact_repo import ArtifactRepository
  from mlflow.utils.file_utils import build_path, get_relative_path
  from mlflow.utils.rest_utils import http_request, http_request_safe, RESOURCE_DOES_NOT_EXIST
  from mlflow.utils.string_utils import strip_prefix
  
  LIST_API_ENDPOINT = '/api/2.0/dbfs/list'
  GET_STATUS_ENDPOINT = '/api/2.0/dbfs/get-status'
  DOWNLOAD_CHUNK_SIZE = 1024
  
  
  class DbfsArtifactRepository(ArtifactRepository):
      """
      Stores artifacts on DBFS.
  
      This repository is used with URIs of the form ``dbfs:/<path>``. The repository can only be used
      together with the RestStore.
      """
  
      def __init__(self, artifact_uri, get_host_creds):
          cleaned_artifact_uri = artifact_uri.rstrip('/')
          super(DbfsArtifactRepository, self).__init__(cleaned_artifact_uri)
          self.get_host_creds = get_host_creds
          if not cleaned_artifact_uri.startswith('dbfs:/'):
              raise MlflowException('DbfsArtifactRepository URI must start with dbfs:/')
  
      def _databricks_api_request(self, endpoint, **kwargs):
          host_creds = self.get_host_creds()
          return http_request_safe(host_creds=host_creds, endpoint=endpoint, **kwargs)
  
      def _dbfs_list_api(self, json):
          host_creds = self.get_host_creds()
          return http_request(
              host_creds=host_creds, endpoint=LIST_API_ENDPOINT, method='GET', json=json)
  
      def _dbfs_download(self, output_path, endpoint):
          with open(output_path, 'wb') as f:
              response = self._databricks_api_request(endpoint=endpoint, method='GET', stream=True)
              try:
                  for content in response.iter_content(chunk_size=DOWNLOAD_CHUNK_SIZE):
                      f.write(content)
              finally:
                  response.close()
  
      def _dbfs_is_dir(self, dbfs_path):
          response = self._databricks_api_request(
              endpoint=GET_STATUS_ENDPOINT, method='GET', json={'path': dbfs_path})
          json_response = json.loads(response.text)
          try:
              return json_response['is_dir']
          except KeyError:
              raise MlflowException('DBFS path %s does not exist' % dbfs_path)
  
      def _get_dbfs_path(self, artifact_path):
          return '/%s/%s' % (strip_prefix(self.artifact_uri, 'dbfs:/'),
                             strip_prefix(artifact_path, '/'))
  
      def _get_dbfs_endpoint(self, artifact_path):
          return "/dbfs%s" % self._get_dbfs_path(artifact_path)
  
      def log_artifact(self, local_file, artifact_path=None):
          basename = os.path.basename(local_file)
          if artifact_path == '':
              raise IllegalArtifactPathError('artifact_path cannot be the empty string.')
          if artifact_path:
              http_endpoint = self._get_dbfs_endpoint(os.path.join(artifact_path, basename))
          else:
              http_endpoint = self._get_dbfs_endpoint(os.path.basename(local_file))
          with open(local_file, 'rb') as f:
              self._databricks_api_request(
                  endpoint=http_endpoint, method='POST', data=f, allow_redirects=False)
  
      def log_artifacts(self, local_dir, artifact_path=None):
          if artifact_path:
              root_http_endpoint = self._get_dbfs_endpoint(artifact_path)
          else:
              root_http_endpoint = self._get_dbfs_endpoint('')
          for (dirpath, _, filenames) in os.walk(local_dir):
              dir_http_endpoint = root_http_endpoint
              if dirpath != local_dir:
                  rel_path = get_relative_path(local_dir, dirpath)
                  dir_http_endpoint = build_path(root_http_endpoint, rel_path)
              for name in filenames:
                  endpoint = build_path(dir_http_endpoint, name)
                  with open(build_path(dirpath, name), 'rb') as f:
                      self._databricks_api_request(
                          endpoint=endpoint, method='POST', data=f, allow_redirects=False)
  
      def list_artifacts(self, path=None):
          if path:
              dbfs_path = self._get_dbfs_path(path)
          else:
              dbfs_path = self._get_dbfs_path('')
          dbfs_list_json = {'path': dbfs_path}
          response = self._dbfs_list_api(dbfs_list_json)
          try:
              json_response = json.loads(response.text)
          except ValueError:
              raise MlflowException(
                  "API request to list files under DBFS path %s failed with status code %s. "
                  "Response body: %s" % (dbfs_path, response.status_code, response.text))
          # /api/2.0/dbfs/list will not have the 'files' key in the response for empty directories.
          infos = []
          artifact_prefix = strip_prefix(self.artifact_uri, 'dbfs:')
          if json_response.get('error_code', None) == RESOURCE_DOES_NOT_EXIST:
              return []
          dbfs_files = json_response.get('files', [])
          for dbfs_file in dbfs_files:
              stripped_path = strip_prefix(dbfs_file['path'], artifact_prefix + '/')
              # If `path` is a file, the DBFS list API returns a single list element with the
              # same name as `path`. The list_artifacts API expects us to return an empty list in this
              # case, so we do so here.
              if stripped_path == path:
                  return []
              is_dir = dbfs_file['is_dir']
              artifact_size = None if is_dir else dbfs_file['file_size']
              infos.append(FileInfo(stripped_path, is_dir, artifact_size))
          return sorted(infos, key=lambda f: f.path)
  
      def _download_file(self, remote_file_path, local_path):
          self._dbfs_download(output_path=local_path,
                              endpoint=self._get_dbfs_endpoint(remote_file_path))
  