Deprecate .spec.serviceAccount Field in ClusterExtension API

[rashmigottipati]

Description

The .spec.serviceAccount field in the ClusterExtension API is being deprecated. This field was originally introduced to enforce least privilege by requiring a user-provided ServiceAccount for managing extension content. However, due to operational complexity and limited benefit, we propose to:

• Mark the field as optional and deprecated.
• Update the controller to ignore this field and use its own ServiceAccount for all reconciliation.
• Log a deprecation warning if the field is set.
• Eventually remove the field entirely in a future update.

Motivation

The .spec.serviceAccount field was originally introduced to enable least privilege by allowing users to specify a custom ServiceAccount for reconciliation. However, this added operational complexity with token management and impersonation. Simplifying this by using the controller’s own ServiceAccount reduces complexity and centralizes permission management, providing a clearer and more maintainable security model.

Impact

• Users relying on .spec.serviceAccount impersonation will need to ensure the controller’s ServiceAccount has appropriate permissions.
• Any manifests using this field will see warnings and should be updated to remove it before its eventual removal.

Tasks:

• Create enhancement proposal in openshift/enhancements repo

• Implement code changes

  • Ignore .spec.serviceAccount in controller logic
  • Update API to mark .spec.serviceAccount as optional and deprecated
  • Remove permissions preflight checks related to serviceAccount
  • Close enhancement proposal

• Update unit tests

  • Remove impersonation-related tests
  • Add tests to verify .spec.serviceAccount is ignored

• Update e2e tests

  • Verify reconciliation works without .spec.serviceAccount
  • Check deprecation warnings are logged when field is set

• Add or update upgrade test scenarios

  • Validate safe CRD schema change and field removal

[rashmigottipati]

PRs:
implementation: #2242
enhancement proposal: openshift/enhancements#1860