Annotating a transformation function results in error

[jmgilman]

Problem description

Annotating parameters in a transformation function results in an error.

Errors & Logs

error: Program failed with an unhandled exception:
    error: Traceback (most recent call last):
      File "/usr/local/bin/pulumi-language-python-exec", line 85, in <module>
        loop.run_until_complete(coro)
      File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/base_events.py", line 587, in run_until_complete
        return future.result()
      File "/Users/josh/code/lab/kube/venv/lib/python3.7/site-packages/pulumi/runtime/stack.py", line 81, in run_in_stack
        await run_pulumi_func(lambda: Stack(func))
      File "/Users/josh/code/lab/kube/venv/lib/python3.7/site-packages/pulumi/runtime/stack.py", line 34, in run_pulumi_func
        func()
      File "/Users/josh/code/lab/kube/venv/lib/python3.7/site-packages/pulumi/runtime/stack.py", line 81, in <lambda>
        await run_pulumi_func(lambda: Stack(func))
      File "/Users/josh/code/lab/kube/venv/lib/python3.7/site-packages/pulumi/runtime/stack.py", line 105, in __init__
        func()
      File "/usr/local/bin/pulumi-language-python-exec", line 84, in <lambda>
        coro = pulumi.runtime.run_in_stack(lambda: runpy.run_path(args.PROGRAM, run_name='__main__'))
      File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 280, in run_path
        run_name, mod_spec, pkg_name).copy()
      File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 85, in _run_code
        exec(code, run_globals)
      File "./__main__.py", line 12, in <module>
        metallb = lb.MetalLB("loadbalancer", lb.MetalLBProperties.from_config(lb_config))
      File "./network/metallb.py", line 62, in __init__
        transformations=[_add_namespace])
      File "/Users/josh/code/lab/kube/venv/lib/python3.7/site-packages/pulumi_kubernetes/yaml.py", line 69, in __init__
        self.resources = _parse_yaml_document(__ret__, opts, transformations, resource_prefix)
      File "/Users/josh/code/lab/kube/venv/lib/python3.7/site-packages/pulumi_kubernetes/yaml.py", line 122, in _parse_yaml_document
        file_objects = _parse_yaml_object(obj, opts, transformations, resource_prefix)
      File "/Users/josh/code/lab/kube/venv/lib/python3.7/site-packages/pulumi_kubernetes/yaml.py", line 150, in _parse_yaml_object
        if len(getargspec(t)[0]) == 2:
      File "/usr/local/Cellar/python/3.7.7/Frameworks/Python.framework/Versions/3.7/lib/python3.7/inspect.py", line 1082, in getargspec
        raise ValueError("Function has keyword-only parameters or annotations"
    ValueError: Function has keyword-only parameters or annotations, use getfullargspec() API which can support them
    error: an unhandled error occurred: Program exited with non-zero exit code: 1

Affected product version(s)

pulumi-vault==2.2.0

Reproducing the issue

The issue can be reproduced by creating a transformation function and annotating the type as seen below:

def _add_namespace(obj: Any):
    obj['metadata']['namespace'] = 'metallb-system'

And then used somewhere as is shown below:

self.resources = yaml.ConfigFile('metallb-resources',
                                         URL,
                                         transformations=[_add_namespace])

Removing the Any annotation resolves the issue.

Suggestions for a fix

I'm not familiar with what is going on under the hood, and I understand that the type annotation, in this case, isn't necessarily required, but it seems like a resolvable bug given the descriptive help message given at the end.

[justinvp]

This is a quick fix.