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Python OAuth client_credentials support (#563)
The current OAuth implementation in the Python client does not reuse access tokens. Instead, it exchanges the client-id and client-secret for a new access token with every request. This behavior increases the load on the tokenEndpoint and introduces unnecessary latency in the request processing. This PR updates the OAuth implementation to oauth reuse access tokens, aligning the Python client with the OAuth behavior of the Scala client, as detailed in this [PR for the Scala client](#553). For additional context on the usage of auth_provider and its functionality, please refer to the description in the original PR for the Spark client.
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# | ||
# Copyright (C) 2021 The Delta Lake Project Authors. | ||
# | ||
# Licensed under the Apache License, Version 2.0 (the "License"); | ||
# you may not use this file except in compliance with the License. | ||
# You may obtain a copy of the License at | ||
# | ||
# http://www.apache.org/licenses/LICENSE-2.0 | ||
# | ||
# Unless required by applicable law or agreed to in writing, software | ||
# distributed under the License is distributed on an "AS IS" BASIS, | ||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
# See the License for the specific language governing permissions and | ||
# limitations under the License. | ||
# | ||
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from abc import ABC, abstractmethod | ||
from datetime import datetime | ||
from typing import Optional | ||
import requests | ||
import base64 | ||
import json | ||
import threading | ||
import requests.sessions | ||
import time | ||
from typing import Dict | ||
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from delta_sharing.protocol import ( | ||
DeltaSharingProfile, | ||
) | ||
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# This module contains internal implementation classes. | ||
# These classes are not part of the public API and should not be used directly by users. | ||
# Internal classes may change or be removed at any time without notice. | ||
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class AuthConfig: | ||
def __init__(self, token_exchange_max_retries=5, | ||
token_exchange_max_retry_duration_in_seconds=60, | ||
token_renewal_threshold_in_seconds=600): | ||
self.token_exchange_max_retries = token_exchange_max_retries | ||
self.token_exchange_max_retry_duration_in_seconds = ( | ||
token_exchange_max_retry_duration_in_seconds) | ||
self.token_renewal_threshold_in_seconds = token_renewal_threshold_in_seconds | ||
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class AuthCredentialProvider(ABC): | ||
@abstractmethod | ||
def add_auth_header(self, session: requests.Session) -> None: | ||
pass | ||
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def is_expired(self) -> bool: | ||
return False | ||
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@abstractmethod | ||
def get_expiration_time(self) -> Optional[str]: | ||
return None | ||
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class BearerTokenAuthProvider(AuthCredentialProvider): | ||
def __init__(self, bearer_token: str, expiration_time: Optional[str]): | ||
self.bearer_token = bearer_token | ||
self.expiration_time = expiration_time | ||
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def add_auth_header(self, session: requests.Session) -> None: | ||
session.headers.update( | ||
{ | ||
"Authorization": f"Bearer {self.bearer_token}", | ||
} | ||
) | ||
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def is_expired(self) -> bool: | ||
if self.expiration_time is None: | ||
return False | ||
try: | ||
expiration_time_as_timestamp = datetime.fromisoformat(self.expiration_time) | ||
return expiration_time_as_timestamp < datetime.now() | ||
except ValueError: | ||
return False | ||
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def get_expiration_time(self) -> Optional[str]: | ||
return self.expiration_time | ||
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class BasicAuthProvider(AuthCredentialProvider): | ||
def __init__(self, endpoint: str, username: str, password: str): | ||
self.username = username | ||
self.password = password | ||
self.endpoint = endpoint | ||
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def add_auth_header(self, session: requests.Session) -> None: | ||
session.auth = (self.username, self.password) | ||
session.post(self.endpoint, data={"grant_type": "client_credentials"},) | ||
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def is_expired(self) -> bool: | ||
return False | ||
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def get_expiration_time(self) -> Optional[str]: | ||
return None | ||
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class OAuthClientCredentials: | ||
def __init__(self, access_token: str, expires_in: int, creation_timestamp: int): | ||
self.access_token = access_token | ||
self.expires_in = expires_in | ||
self.creation_timestamp = creation_timestamp | ||
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class OAuthClient: | ||
def __init__(self, | ||
token_endpoint: str, | ||
client_id: str, | ||
client_secret: str, | ||
scope: Optional[str] = None): | ||
self.token_endpoint = token_endpoint | ||
self.client_id = client_id | ||
self.client_secret = client_secret | ||
self.scope = scope | ||
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def client_credentials(self) -> OAuthClientCredentials: | ||
credentials = base64.b64encode( | ||
f"{self.client_id}:{self.client_secret}".encode('utf-8')).decode('utf-8') | ||
headers = { | ||
'accept': 'application/json', | ||
'authorization': f'Basic {credentials}', | ||
'content-type': 'application/x-www-form-urlencoded' | ||
} | ||
body = f"grant_type=client_credentials{f'&scope={self.scope}' if self.scope else ''}" | ||
response = requests.post(self.token_endpoint, headers=headers, data=body) | ||
response.raise_for_status() | ||
return self.parse_oauth_token_response(response.text) | ||
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def parse_oauth_token_response(self, response: str) -> OAuthClientCredentials: | ||
if not response: | ||
raise RuntimeError("Empty response from OAuth token endpoint") | ||
json_node = json.loads(response) | ||
if 'access_token' not in json_node or not isinstance(json_node['access_token'], str): | ||
raise RuntimeError("Missing 'access_token' field in OAuth token response") | ||
if 'expires_in' not in json_node or not isinstance(json_node['expires_in'], int): | ||
raise RuntimeError("Missing 'expires_in' field in OAuth token response") | ||
return OAuthClientCredentials( | ||
json_node['access_token'], | ||
json_node['expires_in'], | ||
int(datetime.now().timestamp()) | ||
) | ||
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class OAuthClientCredentialsAuthProvider(AuthCredentialProvider): | ||
def __init__(self, oauth_client: OAuthClient, auth_config: AuthConfig = AuthConfig()): | ||
self.auth_config = auth_config | ||
self.oauth_client = oauth_client | ||
self.current_token: Optional[OAuthClientCredentials] = None | ||
self.lock = threading.RLock() | ||
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def add_auth_header(self,session: requests.Session) -> None: | ||
token = self.maybe_refresh_token() | ||
with self.lock: | ||
session.headers.update( | ||
{ | ||
"Authorization": f"Bearer {token.access_token}", | ||
} | ||
) | ||
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def maybe_refresh_token(self) -> OAuthClientCredentials: | ||
with self.lock: | ||
if self.current_token and not self.needs_refresh(self.current_token): | ||
return self.current_token | ||
new_token = self.oauth_client.client_credentials() | ||
self.current_token = new_token | ||
return new_token | ||
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def needs_refresh(self, token: OAuthClientCredentials) -> bool: | ||
now = int(time.time()) | ||
expiration_time = token.creation_timestamp + token.expires_in | ||
return expiration_time - now < self.auth_config.token_renewal_threshold_in_seconds | ||
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def get_expiration_time(self) -> Optional[str]: | ||
return None | ||
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class AuthCredentialProviderFactory: | ||
__oauth_auth_provider_cache : Dict[ | ||
DeltaSharingProfile, | ||
OAuthClientCredentialsAuthProvider] = {} | ||
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@staticmethod | ||
def create_auth_credential_provider(profile: DeltaSharingProfile): | ||
if profile.share_credentials_version == 2: | ||
if profile.type == "oauth_client_credentials": | ||
return AuthCredentialProviderFactory.__oauth_client_credentials(profile) | ||
elif profile.type == "basic": | ||
return AuthCredentialProviderFactory.__auth_basic(profile) | ||
elif (profile.share_credentials_version == 1 and | ||
(profile.type is None or profile.type == "bearer_token")): | ||
return AuthCredentialProviderFactory.__auth_bearer_token(profile) | ||
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# any other scenario is unsupported | ||
raise RuntimeError(f"unsupported profile.type: {profile.type}" | ||
f" profile.share_credentials_version" | ||
f" {profile.share_credentials_version}") | ||
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@staticmethod | ||
def __oauth_client_credentials(profile): | ||
# Once a clientId/clientSecret is exchanged for an accessToken, | ||
# the accessToken can be reused until it expires. | ||
# The Python client re-creates DeltaSharingClient for different requests. | ||
# To ensure the OAuth access_token is reused, | ||
# we keep a mapping from profile -> OAuthClientCredentialsAuthProvider. | ||
# This prevents re-initializing OAuthClientCredentialsAuthProvider for the same profile, | ||
# ensuring the access_token can be reused. | ||
if profile in AuthCredentialProviderFactory.__oauth_auth_provider_cache: | ||
return AuthCredentialProviderFactory.__oauth_auth_provider_cache[profile] | ||
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oauth_client = OAuthClient( | ||
token_endpoint=profile.token_endpoint, | ||
client_id=profile.client_id, | ||
client_secret=profile.client_secret, | ||
scope=profile.scope | ||
) | ||
provider = OAuthClientCredentialsAuthProvider( | ||
oauth_client=oauth_client, | ||
auth_config=AuthConfig() | ||
) | ||
AuthCredentialProviderFactory.__oauth_auth_provider_cache[profile] = provider | ||
return provider | ||
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@staticmethod | ||
def __auth_bearer_token(profile): | ||
return BearerTokenAuthProvider(profile.bearer_token, profile.expiration_time) | ||
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@staticmethod | ||
def __auth_basic(profile): | ||
return BasicAuthProvider(profile.endpoint, profile.username, profile.password) |
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