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Operating System Baseline for HybridOps.Studio

Status

Accepted — HybridOps.Studio standardises on a small, curated set of operating systems for infrastructure, control plane and endpoint simulation, with details captured in the OS Baseline Rationale whitepaper.

1. Context

HybridOps.Studio needs a realistic but manageable OS matrix that:

  • Mirrors what assessors see in real enterprise estates (RHEL-family, Ubuntu, Windows).
  • Works consistently across Proxmox, public cloud and nested labs.
  • Avoids “OS sprawl” that would bloat Packer, Terraform and Ansible work.

The detailed analysis lives in
OS Baseline Rationale.

2. Decision

HybridOps.Studio adopts the following OS baseline:

  • Primary enterprise base: Rocky Linux 9 (future Rocky 10) for core infra and automation.
  • Control / CI layer: Ubuntu 24.04 LTS for ctrl-01, CI/CD and dev-aligned tooling.
  • RHEL-compatible alternative: AlmaLinux 9 as an interchangeable RHEL-compatible option.
  • Windows infrastructure: Windows Server 2022 / 2025 for hybrid identity and infra roles.
  • Endpoint simulation: Windows 11 Pro and optional Android emulation for endpoint/MDM tests.

This baseline is implemented via:

  • Packer templates under infra/packer-multi-os/.
  • Terraform/Ansible vars and roles keyed on os_family.
  • OS selection in blueprints and runbooks based on role, not personal preference.

3. Rationale

  • Enterprise realism: RHEL-compatible + Ubuntu + Windows is a recognisable mix.
  • Lifecycle clarity: Long-lived Rocky/Alma + LTS Ubuntu + LTSC Windows maps cleanly to real support cycles.
  • Tooling fit: HashiCorp stack, Ansible and Kubernetes tooling are well supported on these OSes.
  • Portfolio focus: Keeping the matrix tight avoids wasting time on exotic or niche OS combinations.

The whitepaper OS Baseline Rationale captures:

  • Version choices and support windows.
  • Comparison tables (governance, lifecycle, compliance).
  • How each OS maps to specific platform layers.

4. Consequences

Positive

  • Clear, documented OS story for assessors and students.
  • Lower cognitive load when writing Packer/Ansible roles.
  • Easier evidence capture (you can show “one of each” in a coherent way).

Negative / trade-offs

  • Some interesting OSes (Debian, Fedora, etc.) are deliberately excluded.
  • You must keep templates and roles in sync when OS major versions roll (Rocky 10, next Ubuntu LTS, next Windows LTSC).

5. Implementation notes

  • Packer templates exist per OS under infra/packer-multi-os/.
  • ADR-0016 covers Packer + cloud-init as the template standard.
  • Terraform modules accept an os_family or similar variable to select Rocky/Ubuntu/Windows at plan time.
  • Ansible roles branch on ansible_os_family but share as much logic as possible.

6. References