ManagedIdentityCredential.get_token failed: 'int' object has no attribute 'endswith'

[yikei]

• Package Name: azure-identity
• Package Version: 1.5.0
• Operating System: Linux (Azure VM Standard_D11_v2)
• Python Version: 3.6.8

Describe the bug
ManagedIdentityCredential.get_token fails using azure-identity 1.5.0.

To Reproduce
Running this script in an AzureML experiment:

from azure.identity import ManagedIdentityCredential
credential = ManagedIdentityCredential(client_id='REDACTED')
scope = 'https://storage.azure.com/.default'
access_token = credential.get_token(scope)
print(access_token)

Yields this error:

Traceback (most recent call last):
  File "azid.py", line 4, in <module>
    access_token = credential.get_token(scope)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_internal/decorators.py", line 27, in wrapper
    token = fn(*args, **kwargs)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_credentials/managed_identity.py", line 93, in get_token
    return self._credential.get_token(*scopes, **kwargs)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_credentials/app_service.py", line 38, in get_token
    return super(AppServiceCredential, self).get_token(*scopes, **kwargs)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_internal/get_token_mixin.py", line 70, in get_token
    token = self._request_token(*scopes)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_credentials/app_service.py", line 46, in _request_token
    return self._client.request_token(*scopes, **kwargs)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_internal/managed_identity_client.py", line 73, in request_token
    token = self._process_response(response, request_time)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_internal/managed_identity_client.py", line 91, in _process_response
    self._content_callback(content)
  File "/azureml-envs/azureml_058b99fb4f93bed0f3577d17fc03a78e/lib/python3.6/site-packages/azure/identity/_credentials/app_service.py", line 93, in _parse_app_service_expires_on
    if expires_on.endswith(" +00:00"):
AttributeError: 'int' object has no attribute 'endswith'

Expected behavior
Access token retrieved.

Screenshots
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Additional context
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[chlowell]

Thanks for reporting this! It's the first I've heard of Azure ML managed identity. It happens that Azure ML's managed identity implementation closely resembles App Service's but doesn't behave the same. We'll have to do some work to support it. I'll put this on the backlog while I figure out where it fits into our release schedule.

[yikei]

Thank you, Charles! As a mitigation, we have set our dependency of azure-identity to <1.5.0. Once this issue is resolved we will remove the upper bound.