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Testing RHEL8 Applications on RHEL9#

As part of the migration from RHEL8 to RHEL9, the recommended approach is to rebuild and validate applications on RHEL9.

Best Practice#

Rebuild the application on RHEL9 and create a new modulefile targeting the RHEL9 stack.

Testing Existing RHEL8 Builds#

For compatibility evaluation, existing RHEL8 applications can be exposed by loading:

module load application/rhel8

This extends module search paths to include software built on RHEL8.

Module Dependency Considerations#

RHEL8 applications may rely on modules with changed names, versions, or hierarchy in RHEL9. Some modulefiles may need updates.

Common issues:

  • Renamed dependencies
  • Different compiler or MPI hierarchies
  • Supporting library version changes
  • Missing/deprecated dependencies

Example dependency update:

depends_on("old_dependency/1.0")

May need to become:

depends_on("new_dependency/2.0")

Validation Checklist#

After loading the application module, verify:

  • The module loads without errors.
  • Required dependencies are resolved.
  • Executables are available in the user environment.
  • Basic functionality tests complete successfully.

The compatibility module is a temporary mechanism. Production deployments should use software rebuilt and validated on RHEL9.