Can't resolve Keyvault reference in App Config with managed identity

[nilsga]

Describe the bug

Resolving a keyvault reference through App Config, with a VM managed identity does not work.

Command Name
az appconfig kv list

Errors:

'MSIAuthenticationWrapper' object has no attribute '_token_retriever'

To Reproduce:

Steps to reproduce the behavior.

• Create a VM with a managed identity
• Create a keyvault, and give VM access policy to get and list secrets
• Create an App Config instance
• Add a keyvault reference, say testsecret/keyvaultref
• From the VM, run az appconfig kv list --name <appconfig_name> --key 'testsecret/*' --resolve-keyvault

Expected Behavior

The value should be resolved from the keyvault.

Environment Summary

Linux-5.4.0-1031-azure-x86_64-with-debian-buster-sid
Python 3.6.10
Installer: DEB

azure-cli 2.14.0

Additional Context

Stacktrace:

msrestazure.azure_active_directory : MSI: Token retrieved
azure.cli.core.util.handle_exception is called with an exception:
Traceback (most recent call last):
  File "/opt/az/lib/python3.6/site-packages/azure/cli/command_modules/appconfig/_kv_helpers.py", line 982, in __resolve_secret
    secret_version=kv_identifier.version)
  File "/opt/az/lib/python3.6/site-packages/azure/keyvault/v7_0/key_vault_client.py", line 1843, in get_secret
    response = self._client.send(request, header_parameters, stream=False, **operation_config)
  File "/opt/az/lib/python3.6/site-packages/msrest/service_client.py", line 336, in send
    pipeline_response = self.config.pipeline.run(request, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/msrest/pipeline/__init__.py", line 197, in run
    return first_node.send(pipeline_request, **kwargs)  # type: ignore
  File "/opt/az/lib/python3.6/site-packages/msrest/pipeline/__init__.py", line 150, in send
    response = self.next.send(request, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/msrest/pipeline/requests.py", line 72, in send
    return self.next.send(request, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/msrest/pipeline/requests.py", line 137, in send
    return self.next.send(request, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/msrest/pipeline/__init__.py", line 150, in send
    response = self.next.send(request, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/msrest/pipeline/requests.py", line 193, in send
    self.driver.send(request.http_request, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/msrest/universal_http/requests.py", line 333, in send
    return super(RequestsHTTPSender, self).send(request, **requests_kwargs)
  File "/opt/az/lib/python3.6/site-packages/msrest/universal_http/requests.py", line 142, in send
    **kwargs)
  File "/opt/az/lib/python3.6/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/opt/az/lib/python3.6/site-packages/requests/sessions.py", line 653, in send
    r = dispatch_hook('response', hooks, r, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/requests/hooks.py", line 31, in dispatch_hook
    _hook_data = hook(hook_data, **kwargs)
  File "/opt/az/lib/python3.6/site-packages/azure/keyvault/key_vault_authentication.py", line 146, in _handle_401
    security = self._get_message_security(prep, challenge)
  File "/opt/az/lib/python3.6/site-packages/azure/keyvault/key_vault_authentication.py", line 172, in _get_message_security
    scheme))
  File "/opt/az/lib/python3.6/site-packages/azure/keyvault/key_vault_authentication.py", line 61, in _auth_callback_compat
    if len(inspect.getargspec(self._user_callback).args) == 3 \
  File "/opt/az/lib/python3.6/site-packages/azure/cli/command_modules/appconfig/_kv_helpers.py", line 969, in _get_token
    return Profile(cli_ctx=cli_ctx).get_login_credentials(resource)[0]._token_retriever()  # pylint: disable=protected-access
AttributeError: 'MSIAuthenticationWrapper' object has no attribute '_token_retriever'

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc Shuai Wang (@shenmuxiaosen), Avani Gupta (@avanigupta).

[yonzhan]

appconfig

[shenmuxiaosen]

Hi Nils-Helge Garli Hegvik (@nilsga) ,
Thanks for reporting this issue. It is due to a bug in our implementation that blocks the MSI authentication flow to key vault. It currently only works when login with user account. Will send a fix.

[jiasli]

The code from appconfig is calling _token_retriever:

azure-cli/src/azure-cli/azure/cli/command_modules/appconfig/_kv_helpers.py

Line 969 in d528de3

return Profile(cli_ctx=cli_ctx).get_login_credentials(resource)[0]._token_retriever() # pylint: disable=protected-access

However, _token_retriever is only available for AdalAuthentication which is designed for user and service principal credentials. It is not available for managed identity credential MSIAuthenticationWrapper.

azure-cli/src/azure-cli-core/azure/cli/core/adal_authentication.py

Lines 21 to 24 in 748e1ff

	class AdalAuthentication(Authentication): # pylint: disable=too-few-public-methods
	def __init__(self, token_retriever, external_tenant_token_retriever=None):
	self._token_retriever = token_retriever

Also, _token_retriever is a protected member, so calling it from outside is not supported.

There are 2 correct ways to get a raw token:

1. Call get_raw_token:

   azure-cli/src/azure-cli-core/azure/cli/core/_profile.py

   Line 640 in 2bdd5f2

   def get_raw_token(self, resource=None, subscription=None, tenant=None):

2. (The track 2 approach) Get the credential with get_login_credentials, then call get_token:

   azure-cli/src/azure-cli-core/azure/cli/core/adal_authentication.py

   Line 68 in 748e1ff

   def get_token(self, *scopes, **kwargs): # pylint:disable=unused-argument

If you only need to create a keyvault client, you may simply use the client factory from keyvault command module:

azure-cli/src/azure-cli/azure/cli/command_modules/keyvault/_client_factory.py

Line 128 in 1eed077

def keyvault_data_plane_factory(cli_ctx, _):

It has been proved to work with both user credential and managed identity credential and has better error handling logic. + Bin Ma (@bim-msft) for awareness.

[bim-msft]

Fixed by #15826
Will take effect at our upcoming release train (Nov 17).