feat: configure Python sessions to use PPM instead of PyPI

[ian-flores]

Summary

• Add PythonPackageManagerUrl field to SiteSpec for optional override
• Inject PIP_INDEX_URL into Workbench sessions via launcher-env DCF config
• By default, derives Python PPM URL from Package Manager domain (https://{domain}/pypi/latest/simple)

Test plan

• Unit tests added (3 new tests covering default URL, custom override, PATH+PIP_INDEX_URL combo)
• All 103 controller tests pass
• Manual verification in staging environment

Closes #21

[claude]

Claude finished @ian-flores's task —— View job

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Reviewed all 6 changed files. The implementation follows existing patterns and is well-tested. Posted review with minor suggestions for test completeness.

[claude]

Code Review

Overall this is a clean implementation that follows existing patterns in the codebase. The new Python Package Manager URL functionality integrates well with the existing R package manager URL handling.

Strengths

• Follows the established pattern for URL override (derive from domain by default, allow explicit override)
• Tests cover the three key scenarios: default URL derivation, custom override, and PATH+PIP_INDEX_URL combination
• API field documentation is clear with examples

Suggestions

internal/controller/core/site_test.go

TestSiteReconciler_PythonPPMUrlWithLauncherEnvPath (line 984-1002): This test doesn't verify the actual PIP_INDEX_URL value, only that it exists. Consider adding an assertion for the expected URL value (derived from defaultSite settings) to make the test more robust and self-documenting:

// Add assertion for expected URL
expectedUrl := "https://packagemanager.test.example.com/pypi/latest/simple" // based on defaultSite
assert.Equal(t, expectedUrl, testWorkbench.Spec.Config.WorkbenchDcfConfig.LauncherEnv.Environment["PIP_INDEX_URL"])

api/core/v1beta1/site_types.go

Consider whether +kubebuilder:validation:Pattern would be valuable for PythonPackageManagerUrl to ensure valid URL format at admission time. The existing PackageManagerUrl doesn't have this either, so this is more of a follow-up consideration for both fields.

Controller Checklist

• Reconciliation is idempotent - URL is deterministically derived
• Config flows from Site -> Product correctly
• Unit tests exist (3 new tests)

API Checklist

• Kubebuilder annotations present (omitempty)
• New field has sensible default (derives from Package Manager domain)
• Validation rules - optional, as discussed above

The implementation looks good to merge.