Skip cloud credential method when NO_GCE_CHECK=true

[0x2b3bfa0]

For consistency with googleapis/google-auth-library-python#1610, see fsspec/filesystem_spec#1768 for context.

Summary

• When auto-detecting credentials (method=None), skip the "cloud" method if the NO_GCE_CHECK environment variable is set to "true"
• Avoids unnecessary GCE metadata server requests in environments where GCE is known to be unavailable
• Only affects the auto-detection path; explicit token="cloud" still works

Test plan

• Added test_no_gce_check_skips_cloud to verify _connect_cloud is not called when NO_GCE_CHECK=true
• Existing credential tests still pass

🤖 Generated with Claude Code

[martindurant]

While this clearly gives the option to skip the slow creds step, if a user knows to pass this environment variable, then they probably should know which of the credentials types they need, no?

[0x2b3bfa0]

if a user knows to pass this environment variable, then they probably should know which of the credentials types they need, no?

Indeed! However, there might be cases where the choice of enabling this environment variable isn't up to the user, but up to the platform running the user's code, or to some intermediary library. 🫣

[martindurant]

Fair enough. @ankitaluthra1 , any thoughts on yet-another-envvar? Perhaps this can be a simple keyword argument (in init), so it can be set via the fsspec config system?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.34%. Comparing base (e70bc65) to head (0ecaefb).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #803      +/-   ##
==========================================
+ Coverage   75.98%   76.34%   +0.36%     
==========================================
  Files          14       14              
  Lines        2665     2668       +3     
==========================================
+ Hits         2025     2037      +12     
+ Misses        640      631       -9     

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