Files
cluster-autoscaler-with-capi/docs/decisions.md
T
kacerrandClaude Opus 5.5 57f58f1fc5 Add lab1 workload cluster manifest; workers sized 4 vCPU / 4 GiB
Generated with clusterctl v1.12.11 + the six runbook edits (pod CIDR,
kube-vip v1.2.4, no qcow2, VLAN 4, worker size, no MD replicas); passes
server-side dry run. Inflate test pods lowered to 1Gi to stay CPU-bound,
capacity annotation 4Gi, decision #15.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-27 10:54:44 +02:00

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Decisions

Every direction chosen, rejected or reversed, newest at the bottom. Rows are never rewritten: a reversal is a new row, and the old row's status becomes superseded by #N. Status is active, proposed (not yet confirmed by lab work) or superseded by #N.

Rows 1–9 were back-filled on 2026-09-26 from the README, versions.md, the phase docs and the image-builder fixes log; their dates are when the decision was recorded, not necessarily made.

# Date Decision Alternatives considered Why Status
1 2026-09-24 Pin CAPI core to 1.12.x (versions.md) latest CAPI 1.14.x CAPMOX v0.9.x is only tested against CAPI 1.11/1.12; caps workload Kubernetes and cluster-autoscaler at 1.35 active
2 2026-09-24 Management cluster is k3s on a Proxmox VM kind on a workstation CAPI controllers and the autoscaler must run permanently active
3 2026-09-24 Node images built with kubernetes-sigs/image-builder (Ubuntu 24.04, Proxmox builder) — upstream-maintained CAPI images active
4 2026-09-24 image-builder overrides go in a PACKER_VAR_FILES JSON PACKER_FLAGS flags were silently lost when PACKER_FLAGS was re-exported (fixes log #4) active
5 2026-09-24 Cilium installed by Helm with ipam.mode=kubernetes, pod CIDR 10.244.0.0/16 ClusterResourceSet CNI flavors; pod CIDR 192.168.0.0/16 keeps the CNI version under our control; 192.168.0.0/16 overlaps the lab LAN active
6 2026-09-24 Scale-from-zero via capacity.cluster-autoscaler.kubernetes.io/* annotations on the MachineDeployment infrastructure provider publishing status.capacity CAPMOX does not publish status.capacity on ProxmoxMachineTemplate active
7 2026-09-24 Template only on pv1-1, ALLOWED_NODES=[pv1-1] template on every node; shared storage local-lvm is node-local and there is no shared storage yet active
8 2026-09-26 Phase 2: spike CAPLV first; own provider if insufficient; KubeVirt as fallback (phase-2) CAPK + KubeVirt, Metal3, own provider from the start CAPLV shares CAPI 1.12 with CAPMOX and fits plain libvirt hosts directly proposed
9 2026-09-26 Phases 2 and 3 are independent and can be done in either order strict sequence no technical dependency between the KVM provider and hosted control planes active
10 2026-09-26 Keep project history in the repo: plans, execution logs, session notes, decisions, prompts, reviews, changelog (session) chat history only; raw transcripts committed research repo, reasoning must outlive sessions; transcripts are noisy and may contain secrets active
11 2026-09-27 Cluster inspection by agents only via read-only ServiceAccount kubeconfigs minted by .claude/cluster-inspector/make-kubeconfig.sh (short-lived TokenRequest tokens, gitignored) admin kubeconfig + permission allowlist; long-lived SA token Secret; RBAC under configs/ RBAC (view, no Secrets) enforces read-only regardless of which kubectl verb an agent runs — also closes the kubectl get secret gap from the history-conventions session; short-lived tokens limit leak impact active
12 2026-09-27 Management cluster built by one idempotent Ansible playbook, ansible/mgmt.yml, run from the laptop (plan) cloud-init + k3s auto-deploy manifests; bash scripts with guards; OpenTofu + Helm owner's choice; idempotent modules, one tool; only ansible.builtin, charts through k3s's helm-controller so nothing extra on the VM active
13 2026-09-27 CAPI providers installed by cluster-api-operator 0.28.0 (Provider CRs), cert-manager v1.21.2 pre-installed guarded clusterctl init declarative; re-apply is a no-op; upgrade = spec.version bump; 0.28.0 built against CAPI 1.12.10. Consequence: no clusterctl init/upgrade/move/delete active
14 2026-09-27 Management VM created by the playbook from the pinned Ubuntu 24.04 cloud image (VM 201, 192.168.4.21) hand-made VM; the image-builder node template reproducible from the repo; the image-builder template is a kubeadm node image, not meant for k3s active
15 2026-09-27 lab1 workers 4 vCPU / 4 GiB (not 8 GiB); inflate test pods request 1500m / 1Gi so they stay CPU-bound at 2 per worker 8 GiB workers with 2Gi inflate pods owner's choice to save hypervisor RAM; scale tests keep the 1 → 3 worker shape (configs/capi/lab1.yaml) active