UX: no GCP/R2 credentials but trying to create a GCS/R2 bucket

[concretevitamin]

Repro: on a docker container without GCP credentials, launch this YAML

file_mounts:
  /artifacts:
    name: skypilot-chatbot # Change to your own bucket
    store: gcs
    mode: MOUNT

This first run will print

ImportError: Fail to import dependencies for GCP.Try pip install "skypilot[gcp]"

The second a long stacktrace

  File "/opt/conda/lib/python3.9/site-packages/sky/cli.py", line 1268, in launch
    task = _make_task_from_entrypoint_with_overrides(
  File "/opt/conda/lib/python3.9/site-packages/sky/cli.py", line 997, in _make_task_from_entrypoint_with_overrides
    task = sky.Task.from_yaml(entrypoint)
  File "/opt/conda/lib/python3.9/site-packages/sky/task.py", line 299, in from_yaml
    storage_obj = storage_lib.Storage.from_yaml_config(storage[1])
  File "/opt/conda/lib/python3.9/site-packages/sky/data/storage.py", line 778, in from_yaml_config
    storage_obj.add_store(StoreType(store.upper()))
  File "/opt/conda/lib/python3.9/site-packages/sky/data/storage.py", line 636, in add_store
    store = store_cls(name=self.name, source=self.source)
  File "/opt/conda/lib/python3.9/site-packages/sky/data/storage.py", line 1097, in __init__
    super().__init__(name, source, region, is_sky_managed)
  File "/opt/conda/lib/python3.9/site-packages/sky/data/storage.py", line 175, in __init__
    self.initialize()
  File "/opt/conda/lib/python3.9/site-packages/sky/data/storage.py", line 1129, in initialize
    self.client = gcp.storage_client()
  File "/opt/conda/lib/python3.9/site-packages/sky/adaptors/gcp.py", line 24, in wrapper
    return func(*args, **kwargs)
  File "/opt/conda/lib/python3.9/site-packages/sky/adaptors/gcp.py", line 47, in storage_client
    return storage.Client()
  File "/opt/conda/lib/python3.9/site-packages/google/cloud/storage/client.py", line 172, in __init__
    super(Client, self).__init__(
  File "/opt/conda/lib/python3.9/site-packages/google/cloud/client/__init__.py", line 320, in __init__
    _ClientProjectMixin.__init__(self, project=project, credentials=credentials)
  File "/opt/conda/lib/python3.9/site-packages/google/cloud/client/__init__.py", line 268, in __init__
    project = self._determine_default(project)
  File "/opt/conda/lib/python3.9/site-packages/google/cloud/client/__init__.py", line 287, in _determine_default
    return _determine_default_project(project)
  File "/opt/conda/lib/python3.9/site-packages/google/cloud/_helpers/__init__.py", line 152, in _determine_default_project
    _, project = google.auth.default()
  File "/opt/conda/lib/python3.9/site-packages/google/auth/_default.py", line 648, in default
    raise exceptions.DefaultCredentialsError(_CLOUD_SDK_MISSING_CREDENTIALS)
google.auth.exceptions.DefaultCredentialsError: Your default credentials were not found. To set up Application Default Credentials, see https://cloud.google.com/docs/authentication/external/set-up-adc for more information.

Is there some UX optimization we can do here? E.g., calling global_user_state.get_enabled_clouds() to see GCP is not enabled? cc @romilbhardwaj

[concretevitamin]

Similar issue I ran into (cc @landscapepainter)

file_mounts:
  /tmp:
    name: tmp-workdir
    source: ~/tmp-workdir
    store: r2

prints a long stacktrace

...
  File "/Users/zongheng/Dropbox/workspace/riselab/sky-computing/sky/data/storage.py", line 1479, in initialize
    self.client = data_utils.create_r2_client(self.region)
...
  File "/Users/zongheng/anaconda/envs/py37/lib/python3.7/site-packages/botocore/session.py", line 416, in get_scoped_config
    raise ProfileNotFound(profile=profile_name)
botocore.exceptions.ProfileNotFound: The config profile (r2) could not be found

[landscapepainter]

I'll take a look into this.