Source code for composer.utils.object_store.sftp_object_store

# Copyright 2022 MosaicML Composer authors
# SPDX-License-Identifier: Apache-2.0

"""Utility for uploading to and downloading from cloud object stores."""

from __future__ import annotations

import contextlib
import os
import pathlib
import urllib.parse
import uuid
from typing import Any, Callable, Optional, Union

from composer.utils.import_helpers import MissingConditionalImportError
from composer.utils.object_store.object_store import ObjectStore, ObjectStoreTransientError

__all__ = ['SFTPObjectStore']

    import paramiko.client
    from paramiko import SSHClient
except ImportError:

def _set_kwarg(value: Any, kwargs: dict[str, Any], arg_name: str, kwarg_name: str):
    if kwarg_name in kwargs:
        raise ValueError(f'The `{arg_name}` should be not be specified directly if also included via `connect_kwargs`')
    kwargs[kwarg_name] = value

[docs]class SFTPObjectStore(ObjectStore): """Utility for uploading to and downloading to a server via SFTP. Args: host (str): The server to connect to. Also accepts a URI string in the form ``'sftp://username@host:port/./relative/path'``. For an absolute path, use a double `//` -- e.g. ``'sftp://username@host:port//absolute/path'``. port (int, optional): The server port to connect to. username (str, optional): The username (if not specified in the SSH config) needed to authenticate. Defaults to None. password (str, optional): The password (if required) needed to authenticate. Defaults to None. key_filename (pathlib.Path | str, optional): The filepath to the a private key (if required) needed to authenticate. Defaults to None. Any keys specified here will be tried *in addition* to any keys specified in ``~/.ssh/`` or via a SSH agent. key_filename_environ (str, optional): Environment variable defining path to an SSH keyfile. Only used if key_filename is not provided. Default: ``COMPOSER_SFTP_KEY_FILE``. known_hosts_filename (pathlib.Path | str, optional): The filename of the known hosts file. If not specified, the default SSH known hosts will be used. known_hosts_filename_environ (str, optional). Environment variable defining path to a known hosts file. Only used if known_hosts_filename is not provided. Default: ``COMPOSER_SFTP_KNOWN_HOSTS_FILE``. missing_host_key_policy (str | paramiko.client.MissingHostKeyPolicy, optional): The class name or instance of :class:`paramiko.client.MissingHostKeyPolicy` to use for a missing host key. Defaults to ``'RejectPolicy'``. Built-in options: * ``'RejectPolicy'`` (the default), which will reject any host key not authorized in the ``known_hosts_filename``. * ``'AutoAddPolicy'``, which will add any unknown host key. * ``'WarningPolicy'``, which will warn on an unknown host key. For custom logic, subclass :class:`paramiko.client.MissingHostKeyPolicy`, and provide an instance of this class. cwd (str, optional): The directory to navigate to upon creating the SSH connection. If not present it will be created. connect_kwargs (dict[str, Any], optional): Any additional kwargs to pass through to :meth:`.SSHClient.connect`. """ def __init__( self, host: str, port: int = 22, username: Optional[str] = None, password: Optional[str] = None, known_hosts_filename: Optional[Union[pathlib.Path, str]] = None, known_hosts_filename_environ: str = 'COMPOSER_SFTP_KNOWN_HOSTS_FILE', key_filename: Optional[Union[pathlib.Path, str]] = None, key_filename_environ: str = 'COMPOSER_SFTP_KEY_FILE', missing_host_key_policy: Union[str, paramiko.client.MissingHostKeyPolicy] = 'RejectPolicy', cwd: str = '', connect_kwargs: Optional[dict[str, Any]] = None, ): if known_hosts_filename is None: known_hosts_filename = os.environ.get(known_hosts_filename_environ, None) self.known_hosts_filename = known_hosts_filename if key_filename is None: key_filename = os.environ.get(key_filename_environ, None) self.key_filename = key_filename if not _PARAMIKO_AVAILABLE: raise MissingConditionalImportError(extra_deps_group='streaming', conda_package='paramiko') url = urllib.parse.urlsplit(host) if url.scheme != '': if url.scheme.lower() != 'sftp': raise ValueError('If specifying a URI, only the sftp scheme is supported.') if not url.hostname: raise ValueError('If specifying a URI, the URI must include the hostname.') host = url.hostname if url.username: if username is not None: raise ValueError( 'If specifying the username in the `host`, then the `username` argument must be blank.', ) username = url.username if url.password: if password is not None: raise ValueError( 'If specifying the password in the `host`, then the `password` argument must be blank.', ) password = url.password if url.port: if port != 22: raise ValueError('If specifying the port in the `host`, then the `port` argument must be blank.') port = url.port if url.path: # strip the first left slash. Two slashes for absolute; 1 for relative assert url.path.startswith('/'), 'The path should always start with a `/`' cwd = url.path[1:] if url.query or url.fragment: raise ValueError('Query and fragment parameters are not supported as part of a URI.') if connect_kwargs is None: connect_kwargs = {} if host: _set_kwarg(host, connect_kwargs, arg_name='host', kwarg_name='hostname') if port: _set_kwarg(port, connect_kwargs, arg_name='port', kwarg_name='port') if username: _set_kwarg(username, connect_kwargs, arg_name='username', kwarg_name='username') if password: _set_kwarg(password, connect_kwargs, arg_name='password', kwarg_name='password') if key_filename: _set_kwarg(key_filename, connect_kwargs, arg_name='key_filename', kwarg_name='key_filename') if cwd and not cwd.endswith('/'): cwd += '/' self.cwd = cwd netloc = '' if username: netloc += f'{username}@' if host: netloc += host if port: netloc += f':{port}' self._base_uri = urllib.parse.urlunsplit(( 'sftp', # scheme netloc, # netloc '/' + cwd, # path None, # query None, # fragment )) self.ssh_client = SSHClient() if known_hosts_filename is not None: known_hosts_filename = str(known_hosts_filename) if isinstance(missing_host_key_policy, str): try: missing_host_key_policy = getattr(paramiko.client, missing_host_key_policy)() assert isinstance(missing_host_key_policy, paramiko.client.MissingHostKeyPolicy) except AttributeError: raise ValueError( "Invalid `missing_host_key_policy`. Must be 'AutoAddPolicy', 'RejectPolicy', or 'WarningPolicy'.", ) self.ssh_client.set_missing_host_key_policy(missing_host_key_policy) self.ssh_client.load_system_host_keys(known_hosts_filename) self._connect_kwargs = connect_kwargs self.ssh_client.connect(**connect_kwargs) self.sftp_client = self.ssh_client.open_sftp() def close(self): self.sftp_client.close() self.ssh_client.close() def get_uri(self, object_name: str) -> str: return self._base_uri + object_name def get_object_size(self, object_name: str) -> int: object_name = os.path.join(self.cwd, object_name) with self._handle_transient_errors(): st_size = self.sftp_client.stat(object_name).st_size if st_size is None: raise RuntimeError('Cannot determine object size: stat(object_name).st_size is None') return st_size @contextlib.contextmanager def _handle_transient_errors(self): from paramiko import ChannelException, SSHException try: yield except Exception as e: if not self._is_cnx_alive(): # If the connection dropped, then it's a transient error. Create a new one, and raise the exception to try again. self.close() self.ssh_client.connect(**self._connect_kwargs) self.sftp_client = self.ssh_client.open_sftp() raise ObjectStoreTransientError from e if isinstance(e, SSHException): if 'Server connection dropped:' in str(e): raise ObjectStoreTransientError from e if isinstance(e, (TimeoutError, ConnectionError, EOFError, ChannelException)): raise ObjectStoreTransientError from e raise e def _is_cnx_alive(self): transport = self.ssh_client.get_transport() assert transport is not None, 'transport should not be None' if not transport.is_active() or not transport.is_alive(): return False channel = self.sftp_client.get_channel() assert channel is not None, 'channels not be None if the transport is alive' return and not channel.closed def upload_object( self, object_name: str, filename: Union[str, pathlib.Path], callback: Optional[Callable[[int, int], None]] = None, ) -> None: remote_object_name = os.path.join(self.cwd, object_name) dirname = os.path.dirname(remote_object_name) with self._handle_transient_errors(): if dirname: self.ssh_client.exec_command(f'mkdir -p {dirname}') self.sftp_client.put(str(filename), remote_object_name, callback=callback, confirm=False) # Validating manually to raise ObjectStoreTransientErrors if the size mismatches # This logic was adapted from the original source -- see # local_file_size = os.stat(filename).st_size remote_file_size = self.get_object_size(object_name) if local_file_size != remote_file_size: raise ObjectStoreTransientError( f'Size mismatch in put: local size ({local_file_size}) != remote size ({remote_file_size})', ) def download_object( self, object_name: str, filename: Union[str, pathlib.Path], overwrite: bool = False, callback: Optional[Callable[[int, int], None]] = None, ) -> None: object_name = os.path.join(self.cwd, object_name) dirname = os.path.dirname(filename) if dirname: os.makedirs(dirname, exist_ok=True) if os.path.exists(filename) and not overwrite: raise FileExistsError(f'The file at {filename} already exists') tmp_path = str(filename) + f'.{uuid.uuid4()}.tmp' try: with self._handle_transient_errors(): self.sftp_client.get(remotepath=object_name, localpath=tmp_path, callback=callback) except Exception: # Make a best effort attempt to clean up the temporary file try: os.remove(tmp_path) except OSError: pass raise else: if overwrite: os.replace(tmp_path, filename) else: os.rename(tmp_path, filename)