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"""
This sample demonstrates a daemon application that acquires a token using a
managed identity and then calls a web API with the token.
This sample loads its configuration from a .env file.
To make this sample work, you need to choose this template:
.env.sample.managed_identity
Copy the chosen template to a new file named .env, and fill in the values.
You can then run this sample:
python name_of_this_script.py
"""
import json
import logging
import os
import time
from dotenv import load_dotenv # Need "pip install python-dotenv"
import msal
import requests
# Optional logging
# logging.basicConfig(level=logging.DEBUG) # Enable DEBUG log for entire script
# logging.getLogger("msal").setLevel(logging.INFO) # Optionally disable MSAL DEBUG logs
load_dotenv() # We use this to load configuration from a .env file
# If for whatever reason you plan to recreate same ClientApplication periodically,
# you shall create one global token cache and reuse it by each ClientApplication
global_token_cache = msal.TokenCache() # The TokenCache() is in-memory.
# See more options in https://msal-python.readthedocs.io/en/latest/#tokencache
# Create a managed identity instance based on the environment variable value
if os.getenv('MANAGED_IDENTITY'):
managed_identity = json.loads(os.getenv('MANAGED_IDENTITY'))
else:
managed_identity = msal.SystemAssignedManagedIdentity()
# Create a preferably long-lived app instance, to avoid the overhead of app creation
global_app = msal.ManagedIdentityClient(
managed_identity,
http_client=requests.Session(),
token_cache=global_token_cache, # Let this app (re)use an existing token cache.
# If absent, ClientApplication will create its own empty token cache
)
resource = os.getenv("RESOURCE")
def acquire_and_use_token():
# ManagedIdentityClient.acquire_token_for_client(...) will automatically look up
# a token from cache, and fall back to acquire a fresh token when needed.
result = global_app.acquire_token_for_client(resource=resource)
if "access_token" in result:
if os.getenv('ENDPOINT'):
# Calling a web API using the access token
api_result = requests.get(
os.getenv('ENDPOINT'),
headers={'Authorization': 'Bearer ' + result['access_token']},
).json() # Assuming the response is JSON
print("Web API call result", json.dumps(api_result, indent=2))
else:
print("Token acquisition result", json.dumps(result, indent=2))
else:
print("Token acquisition failed", result) # Examine result["error_description"] etc. to diagnose error
while True: # Here we mimic a long-lived daemon
acquire_and_use_token()
print("Press Ctrl-C to stop.")
time.sleep(5) # Let's say your app would run a workload every X minutes
|
