jakman85andClaude Opus 4.8
e8c555cfeb
Greenfield spec set for a GitOps-driven PaaS+IaaS home platform: vision & requirements (R-* IDs), architecture, 14 domain specs, 11 ADRs, roadmap (phases + workstreams), and AI-agent coordination (roles, protocol, definition-of-done, task board). Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
37 lines
2.0 KiB
Markdown
37 lines
2.0 KiB
Markdown
# ADR-0005 — VM workloads: KubeVirt + CDI
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- Status: Accepted
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- Date: 2026-08-15
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- Serves: R-PLAT-03, R-PLAT-04, R-STATE-01
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- Supersedes: —
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## Context
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Not everything fits in a container. The platform must run VMs, but the operator must manage them
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through the **same** Kubernetes API/CLI/YAML/GitOps as containers, with the same network isolation,
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egress classes, storage durability, and observability — no separate hypervisor management plane for
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application workloads.
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## Decision
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Use **KubeVirt** to run application VMs as Kubernetes custom resources (`VirtualMachine` /
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`VirtualMachineInstance`), with **CDI (Containerized Data Importer)** to provision VM disks onto
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**Longhorn** PVCs. VMs run on the same Cilium network (inheriting default-deny + egress classes) and
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are managed by Flux like any other workload. `virtctl` provides console/lifecycle helpers alongside
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`kubectl`.
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## Alternatives considered
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- **Proxmox / standalone hypervisor + separate IaC** — a second management plane and tooling; breaks
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the "same Kubernetes surface" requirement (R-PLAT-03). (The operator's prior environment used
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Proxmox; this platform deliberately unifies on Kubernetes instead.)
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- **Harvester (SUSE)** — HCI built on KubeVirt; heavier and opinionated about the whole node OS; k3s
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+ KubeVirt keeps one lightweight cluster for both containers and VMs.
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- **Containers only** — rejected: the requirement explicitly needs a VM escape hatch.
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## Consequences
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- One control plane, one GitOps flow, one network/storage/observability model for containers *and*
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VMs.
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- Nodes must expose virtualization extensions (nested virt in dev KVMs; native on prod) — a node
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baseline prerequisite ([02](../docs/02-environments-and-provisioning.md)).
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- VMs are heavier than pods; capacity planning on the 3-node cluster must account for them.
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- At least one representative VM workload must be proven in dev/test so the IaaS path is real
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([06](../docs/06-vm-workloads-kubevirt.md)).
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- VM guest updates use in-guest automation (R-UPD-*), distinct from container image tag bumps.
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