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#!/usr/bin/env python
# --------------------------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See License.txt in the project root for license information.
# --------------------------------------------------------------------------------------------
"""
Example to demonstrate utilizing SAS (Shared Access Signature) tokens to authenticate with ServiceBus
"""
# pylint: disable=C0111
import asyncio
import os
import time
import hmac
import hashlib
import base64
try:
from urllib.parse import quote as url_parse_quote
except ImportError:
from urllib import pathname2url as url_parse_quote
from azure.core.credentials import AccessToken
from azure.eventhub.aio import EventHubConsumerClient
def generate_sas_token(uri, sas_name, sas_value, token_ttl):
"""Performs the signing and encoding needed to generate a sas token from a sas key."""
sas = sas_value.encode('utf-8')
expiry = str(int(time.time() + token_ttl))
string_to_sign = (uri + '\n' + expiry).encode('utf-8')
signed_hmac_sha256 = hmac.HMAC(sas, string_to_sign, hashlib.sha256)
signature = url_parse_quote(base64.b64encode(signed_hmac_sha256.digest()))
return 'SharedAccessSignature sr={}&sig={}&se={}&skn={}'.format(uri, signature, expiry, sas_name)
class CustomizedSASCredential(object):
def __init__(self, token, expiry):
"""
:param str token: The token string
:param float expiry: The epoch timestamp
"""
self.token = token
self.expiry = expiry
self.token_type = b"servicebus.windows.net:sastoken"
async def get_token(self, *scopes, **kwargs):
"""
This method is automatically called when token is about to expire.
"""
return AccessToken(self.token, self.expiry)
# Target namespace and hub must also be specified. Consumer group is set to default unless required otherwise.
FULLY_QUALIFIED_NAMESPACE = os.environ['EVENT_HUB_HOSTNAME']
EVENTHUB_NAME = os.environ['EVENT_HUB_NAME']
CONSUMER_GROUP = "$Default"
# The following part creates a SAS token. Users can use any way to create a SAS token.
SAS_POLICY = os.environ['EVENT_HUB_SAS_POLICY']
SAS_KEY = os.environ['EVENT_HUB_SAS_KEY']
async def create_with_sas_token():
uri = "sb://{}/{}".format(FULLY_QUALIFIED_NAMESPACE, EVENTHUB_NAME)
token_ttl = 3000 # seconds
sas_token = generate_sas_token(uri, SAS_POLICY, SAS_KEY, token_ttl)
# end of creating a SAS token
consumer_client = EventHubConsumerClient(
fully_qualified_namespace=FULLY_QUALIFIED_NAMESPACE,
eventhub_name=EVENTHUB_NAME,
consumer_group=CONSUMER_GROUP,
credential=CustomizedSASCredential(sas_token, time.time() + token_ttl),
logging_enable=True
)
async def on_event(context, event):
print(context.partition_id, ":", event)
async with consumer_client:
await consumer_client.receive(
on_event,
starting_position=-1
)
loop = asyncio.get_event_loop()
loop.run_until_complete(create_with_sas_token())
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