Azure CLI k8s-extension Installation Fails Due to Missing maturin Dependency

### Describe the bug

Installing the Azure CLI k8s-extension fails during dependency installation on Windows.

Environment:
- Operating system: Windows
- Azure CLI version: 2.90.0 (latest released version)
- Extension: k8s-extension

Steps to reproduce:
1. Install Azure CLI version 2.90.0.
2. Run:
az version
3. Run:
az extension add --name k8s-extension --debug

Behavior:
The extension downloads successfully and passes checksum validation. However, installation fails while pip is resolving and building the cryptography dependency.

The command ends with:

pip._vendor.pyproject_hooks._impl.BackendUnavailable:
Cannot import 'maturin'

Azure CLI then reports:

An error occurred. Pip failed with status code 2.

The k8s-extension is not installed.

Relevant output:
Collecting cryptography>=41.0.5
Downloading cryptography-50.0.1.tar.gz
Installing build dependencies: started
Installing build dependencies: finished with status 'done'
Getting requirements to build wheel: started
Getting requirements to build wheel: finished with status 'done'

pip._vendor.pyproject_hooks._impl.BackendUnavailable:
Cannot import 'maturin'

### Related command

az extension add -n k8s-extension --debug

### Errors

pip._vendor.pyproject_hooks._impl.BackendUnavailable: Cannot import 'maturin'

### Issue script & Debug output

Collecting kubernetes==24.2.0 (from k8s-extension==1.8.0)
Downloading kubernetes-24.2.0-py2.py3-none-any.whl.metadata (1.5 kB)
Collecting oras==0.2.25 (from k8s-extension==1.8.0)
Downloading oras-0.2.25-py3-none-any.whl.metadata (11 kB)
Collecting azure-mgmt-network>=18.0.0 (from k8s-extension==1.8.0)
Downloading azure_mgmt_network-32.0.0-py3-none-any.whl.metadata (129 kB)
Collecting certifi>=14.05.14 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading certifi-2026.7.22-py3-none-any.whl.metadata (2.5 kB)
Collecting six>=1.9.0 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading six-1.17.0-py2.py3-none-any.whl.metadata (1.7 kB)
Collecting python-dateutil>=2.5.3 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading python_dateutil-2.9.0.post0-py2.py3-none-any.whl.metadata (8.4 kB)
Collecting setuptools>=21.0.0 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading setuptools-84.0.0-py3-none-any.whl.metadata (6.6 kB)
Collecting pyyaml>=5.4.1 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading pyyaml-6.0.3.tar.gz (130 kB)
Installing build dependencies: started
Installing build dependencies: finished with status 'done'
Getting requirements to build wheel: started
Getting requirements to build wheel: finished with status 'done'
Preparing metadata (pyproject.toml): started
Preparing metadata (pyproject.toml): finished with status 'done'
Collecting google-auth>=1.0.1 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading google_auth-2.58.0-py3-none-any.whl.metadata (6.0 kB)
Collecting websocket-client!=0.40.0,!=0.41.*,!=0.42.*,>=0.32.0 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading websocket_client-1.9.2-py3-none-any.whl.metadata (8.3 kB)
Collecting requests (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading requests-2.34.2-py3-none-any.whl.metadata (4.8 kB)
Collecting requests-oauthlib (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading requests_oauthlib-2.0.0-py2.py3-none-any.whl.metadata (11 kB)
Collecting urllib3>=1.24.2 (from kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading urllib3-2.7.0-py3-none-any.whl.metadata (6.9 kB)
Collecting jsonschema (from oras==0.2.25->k8s-extension==1.8.0)
Downloading jsonschema-4.26.0-py3-none-any.whl.metadata (7.6 kB)
Collecting isodate>=0.6.1 (from azure-mgmt-network>=18.0.0->k8s-extension==1.8.0)
Downloading isodate-0.7.2-py3-none-any.whl.metadata (11 kB)
Collecting azure-mgmt-core>=1.6.0 (from azure-mgmt-network>=18.0.0->k8s-extension==1.8.0)
Downloading azure_mgmt_core-1.6.0-py3-none-any.whl.metadata (4.6 kB)
Collecting typing-extensions>=4.6.0 (from azure-mgmt-network>=18.0.0->k8s-extension==1.8.0)
Downloading typing_extensions-4.16.0-py3-none-any.whl.metadata (3.3 kB)
Collecting azure-core>=1.32.0 (from azure-mgmt-core>=1.6.0->azure-mgmt-network>=18.0.0->k8s-extension==1.8.0)
Downloading azure_core-1.41.0-py3-none-any.whl.metadata (49 kB)
Collecting pyasn1-modules>=0.2.1 (from google-auth>=1.0.1->kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading pyasn1_modules-0.4.2-py3-none-any.whl.metadata (3.5 kB)
Collecting cryptography>=41.0.5 (from google-auth>=1.0.1->kubernetes==24.2.0->k8s-extension==1.8.0)
Downloading cryptography-50.0.1.tar.gz (880 kB)
---------------------------------------- 880.4/880.4 kB 5.7 MB/s 0:00:00
Installing build dependencies: started
Installing build dependencies: finished with status 'done'
Getting requirements to build wheel: started
Getting requirements to build wheel: finished with status 'done'
ERROR: Exception:
Traceback (most recent call last):
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\cli\base_command.py", line 109, in _run_wrapper
status = _inner_run()
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\cli\base_command.py", line 102, in _inner_run
return self.run(options, args)
~~~~~~~~^^^^^^^^^^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\cli\req_command.py", line 106, in wrapper
return func(self, options, args)
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\commands\install.py", line 478, in run
requirement_set = resolver.resolve(
reqs, check_supported_wheels=not options.target_dir
)
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\resolver.py", line 103, in resolve
result = self._result = resolver.resolve(
~~~~~~~~~~~~~~~~^
collected.requirements, max_rounds=limit_how_complex_resolution_can_be
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\resolvelib\resolvers\resolution.py", line 601, in resolve
state = resolution.resolve(requirements, max_rounds=max_rounds)
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\resolvelib\resolvers\resolution.py", line 513, in resolve
failure_criterion = self._attempt_to_pin_criterion(name)
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\resolvelib\resolvers\resolution.py", line 220, in _attempt_to_pin_criterion
criteria = self._get_updated_criteria(candidate)
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\resolvelib\resolvers\resolution.py", line 211, in _get_updated_criteria
self._add_to_criteria(criteria, requirement, parent=candidate)
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\resolvelib\resolvers\resolution.py", line 150, in _add_to_criteria
if not criterion.candidates:
^^^^^^^^^^^^^^^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\resolvelib\structs.py", line 194, in __bool__
return bool(self._sequence)
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\found_candidates.py", line 165, in __bool__
self._bool = any(self)
~~~^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\found_candidates.py", line 149, in
return (c for c in iterator if id(c) not in self._incompatible_ids)
^^^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\found_candidates.py", line 39, in _iter_built
candidate = func()
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\factory.py", line 181, in _make_candidate_from_link
base: BaseCandidate | None = self._make_base_candidate_from_link(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
link, template, name, version
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\factory.py", line 227, in _make_base_candidate_from_link
self._link_candidate_cache[link] = LinkCandidate(
~~~~~~~~~~~~~^
link,
^^^^^
...<3 lines>...
version=version,
^^^^^^^^^^^^^^^^
)
^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 325, in __init__
super().__init__(
~~~~~~~~~~~~~~~~^
link=link,
^^^^^^^^^^
...<4 lines>...
version=version,
^^^^^^^^^^^^^^^^
)
^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 167, in __init__
self.dist = self._prepare()
~~~~~~~~~~~~~^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 245, in _prepare
dist = self._prepare_distribution()
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\resolution\resolvelib\candidates.py", line 336, in _prepare_distribution
return preparer.prepare_linked_requirement(self._ireq, parallel_builds=True)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\operations\prepare.py", line 664, in prepare_linked_requirement
return self._prepare_linked_requirement(req, parallel_builds)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\operations\prepare.py", line 783, in _prepare_linked_requirement
dist = _get_prepared_distribution(
req,
...<4 lines>...
self.allow_editables,
)
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\operations\prepare.py", line 82, in _get_prepared_distribution
abstract_dist.prepare_distribution_metadata(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
build_env_installer, build_isolation, check_build_deps, allow_editables
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\distributions\sdist.py", line 63, in prepare_distribution_metadata
self._install_build_reqs(
~~~~~~~~~~~~~~~~~~~~~~~~^
build_env_installer, build_isolation, allow_editables=allow_editables
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\distributions\sdist.py", line 159, in _install_build_reqs
build_reqs = self._get_build_requires_wheel()
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\distributions\sdist.py", line 131, in _get_build_requires_wheel
return backend.get_requires_for_build_wheel()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_internal\utils\misc.py", line 734, in get_requires_for_build_wheel
return super().get_requires_for_build_wheel(config_settings=cs)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\pyproject_hooks\_impl.py", line 196, in get_requires_for_build_wheel
return self._call_hook(
~~~~~~~~~~~~~~~^
"get_requires_for_build_wheel", {"config_settings": config_settings}
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "C:\Program Files (x86)\Microsoft SDKs\Azure\CLI2\Lib\site-packages\pip\_vendor\pyproject_hooks\_impl.py", line 402, in _call_hook
raise BackendUnavailable(
...<4 lines>...
)
pip._vendor.pyproject_hooks._impl.BackendUnavailable: Cannot import 'maturin'

### Expected behavior

The k8s-extension installs successfully with all required dependencies.

### Environment Summary

azure-cli 2.90.0

core 2.90.0
telemetry 1.1.0

Extensions:
k8s-configuration 2.3.0

Dependencies:
msal 1.36.0
azure-mgmt-resource 24.0.0

Python (Windows) 3.14.6 (tags/v3.14.6:c63aec6, Jun 10 2026, 10:13:15) [MSC v.1944 32 bit (Intel)]

Legal docs and information: aka.ms/AzureCliLegal

Your CLI is up-to-date.

### Additional context

_No response_