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"""
The configuration file would look like this (sans those // comments):
{
"tenant": "your_tenant_name",
// Your target tenant, DNS name
"client_id": "your_client_id came from https://learn.microsoft.com/entra/identity-platform/quickstart-register-app",
// Target app ID in Azure AD
"scope": ["https://graph.microsoft.com/.default"],
// Specific to Client Credentials Grant i.e. acquire_token_for_client(),
// you don't specify, in the code, the individual scopes you want to access.
// Instead, you statically declared them when registering your application.
// Therefore the only possible scope is "resource/.default"
// (here "https://graph.microsoft.com/.default")
// which means "the static permissions defined in the application".
"vault_tenant": "your_vault_tenant_name",
// Your Vault tenant may be different to your target tenant
// If that's not the case, you can set this to the same
// as "tenant"
"vault_clientid": "your_vault_client_id",
// Client ID of your vault app in your vault tenant
"vault_clientsecret": "your_vault_client_secret",
// Secret for your vault app
"vault_url": "your_vault_url",
// URL of your vault app
"cert": "your_cert_name",
// Name of your certificate in your vault
"cert_thumb": "your_cert_thumbprint",
// Thumbprint of your certificate
"endpoint": "https://graph.microsoft.com/v1.0/users"
// For this resource to work, you need to visit Application Permissions
// page in portal, declare scope User.Read.All, which needs admin consent
// https://github.com/Azure-Samples/ms-identity-python-daemon/blob/master/2-Call-MsGraph-WithCertificate/README.md
}
You can then run this sample with a JSON configuration file:
python sample.py parameters.json
"""
import base64
import json
import logging
import requests
import sys
import time
import uuid
import msal
# Optional logging
# logging.basicConfig(level=logging.DEBUG) # Enable DEBUG log for entire script
# logging.getLogger("msal").setLevel(logging.INFO) # Optionally disable MSAL DEBUG logs
from azure.keyvault import KeyVaultClient, KeyVaultAuthentication
from azure.common.credentials import ServicePrincipalCredentials
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
config = json.load(open(sys.argv[1]))
def auth_vault_callback(server, resource, scope):
credentials = ServicePrincipalCredentials(
client_id=config['vault_clientid'],
secret=config['vault_clientsecret'],
tenant=config['vault_tenant'],
resource='https://vault.azure.net'
)
token = credentials.token
return token['token_type'], token['access_token']
def make_vault_jwt():
header = {
'alg': 'RS256',
'typ': 'JWT',
'x5t': base64.b64encode(
config['cert_thumb'].decode('hex'))
}
header_b64 = base64.b64encode(json.dumps(header).encode('utf-8'))
body = {
'aud': "https://login.microsoftonline.com/%s/oauth2/token" %
config['tenant'],
'exp': (int(time.time()) + 600),
'iss': config['client_id'],
'jti': str(uuid.uuid4()),
'nbf': int(time.time()),
'sub': config['client_id']
}
body_b64 = base64.b64encode(json.dumps(body).encode('utf-8'))
full_b64 = b'.'.join([header_b64, body_b64])
client = KeyVaultClient(KeyVaultAuthentication(auth_vault_callback))
chosen_hash = hashes.SHA256()
hasher = hashes.Hash(chosen_hash, default_backend())
hasher.update(full_b64)
digest = hasher.finalize()
signed_digest = client.sign(config['vault_url'],
config['cert'], '', 'RS256',
digest).result
full_token = b'.'.join([full_b64, base64.b64encode(signed_digest)])
return full_token
# 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 preferably long-lived app instance, to avoid the overhead of app creation
global_app = msal.ConfidentialClientApplication(
config['client_id'],
authority="https://login.microsoftonline.com/%s" % config['tenant'],
client_credential={"client_assertion": make_vault_jwt()},
token_cache=global_token_cache, # Let this app (re)use an existing token cache.
# If absent, ClientApplication will create its own empty token cache
)
def acquire_and_use_token():
# Since MSAL 1.23, 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(scopes=config["scope"])
if "access_token" in result:
print("Token was obtained from:", result["token_source"]) # Since MSAL 1.25
# Calling graph using the access token
graph_data = requests.get( # Use token to call downstream service
config["endpoint"],
headers={'Authorization': 'Bearer ' + result['access_token']},).json()
print("Graph API call result: %s" % json.dumps(graph_data, 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
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