home-network-k3s-impl/clusters/README.md

clusters/

Flux entrypoints and the environment-overlay model (R-ENV-02, R-GITOPS-01/02/03).

Governing spec: docs/05-gitops-and-delivery.md, docs/02-environments-and-provisioning.md, ADR-0004 (Flux).

Phase 0 scaffolding only. These are structurally-correct stubs. No cluster exists — nothing here reconciles until WS-INFRA delivers a cluster and bootstraps Flux (roadmap Phase 1).

Layout — base + overlay (never fork the base)

clusters/
  base/                 shared Flux objects (one authoring, both environments)
    flux-system.yaml    GitRepository — the reconciliation source (bootstrap → Gitea)
    platform.yaml       Flux Kustomization → ./platform   (reconciles first)
    apps-wave-0.yaml    Flux Kustomization → ./apps/wave-0 (dependsOn platform-config)
    apps-wave-1.yaml    Flux Kustomization → ./apps/wave-1 (dependsOn apps-wave-0)
    apps-wave-2.yaml    Flux Kustomization → ./apps/wave-N (dependsOn apps-wave-N-1)
    cluster-vars.yaml   ConfigMap of overlay knobs (BASE defaults)
    kustomization.yaml
  dev/                  ACTIVE build target — patches cluster-vars with dev values only
    kustomization.yaml
  prod/                 DESIGN-ONLY until roadmap Phase 7 — patches cluster-vars with prod values only
    kustomization.yaml

How the overlay model satisfies R-ENV-02

The base authors the reconciliation graph once. platform.yaml and the app-wave Kustomizations (apps-wave-0/1/2.yaml — the single apps.yaml was retired; apps-vms.yaml deliberately omits it, see below) declare postBuild.substituteFrom the cluster-vars ConfigMap. Platform and app manifests use ${TOKEN} placeholders for every value that legitimately differs between environments (issuer, replica counts, storage sizes, retention, node placement).

clusters/dev and clusters/prod differ ONLY by the values they patch into cluster-vars — they add no resources of their own and never copy/fork a base manifest. Promotion to prod (docs/02) is a change to the prod overlay's variables, nothing else.

LAN addressing is a knob, not a literal (fixed 2026-08-31)

Until 2026-08-31 the base manifests hardcoded the dev LAN: the k3s API host Cilium dials, the Cilium LB IP pool range, the pinned crafty/unifi L4 VIPs and the off-cluster S3 backup endpoint. That broke R-ENV-02 outright — clusters/prod would have rendered dev addresses (192.168.1.x) onto the prod LAN (192.168.2.x). They are now the cluster-vars "LAN addressing" block (K3S_API_HOST, CILIUM_LB_POOL_START/_STOP, UNIFI_L4_VIP, CRAFTY_L4_VIP, S3_BACKUP_ENDPOINT, alongside the pre-existing GATEWAY_VIP), set explicitly by BOTH overlays.

Two rules when touching that block:

1. Substitution coverage. A ${TOKEN} only resolves in a path whose Flux Kustomization declares postBuild.substituteFrom: cluster-vars; anywhere else the literal string ${TOKEN} ships to the cluster. apps-vms was the one path without it and now has it — which means every shell ${...} in a VM manifest's cloud-init must be escaped $${...} (see clusters/base/apps-vms.yaml for the full envsubst escape contract).
2. GATEWAY_VIP must be inside CILIUM_LB_POOL_START..STOP, and in practice equal to START: the shared Gateway pins no address, so Cilium LB-IPAM gives it the pool's first free IP while split-horizon CoreDNS answers with ${GATEWAY_VIP}. A VIP outside the pool blackholes in-cluster hairpin traffic while the Gateway still looks healthy.

Values the operator has not decided are TBD-PROD-* placeholders, not guesses: prod inherits the DEV base defaults if an overlay op is simply omitted, so an invalid value that fails loudly is strictly safer than a plausible one that quietly comes up on the wrong network.

How Flux is pointed at an environment

flux bootstrap (run by WS-INFRA in Phase 1) targets one environment's path per cluster:

# dev cluster
flux bootstrap ... --path=clusters/dev
# prod cluster (Phase 7 only — design-only until then)
flux bootstrap ... --path=clusters/prod

Bootstrap materializes the flux-system Kustomization that renders the chosen overlay, which pulls in base/ and applies the env-scoped cluster-vars.

Reconciliation order

GitRepository (flux-system)
        │
        ▼
Kustomization: platform  (./platform, substituteFrom cluster-vars)
        │  healthy
        ▼
Kustomization: apps-wave-0  (./apps/wave-0, dependsOn platform-config, substituteFrom cluster-vars)
        │  healthy
        ▼
Kustomization: apps-wave-1  (./apps/wave-1, dependsOn apps-wave-0)
        │  healthy
        ▼
Kustomization: apps-wave-N  (./apps/wave-N, dependsOn apps-wave-N-1)

Wave 0 dependsOn platform-config (transitively platform) so CNI/storage/TLS/DNS/gateway exist before any workload reconciles. The app tier is split into dependency-ordered WAVES (catalog/render.py --emit-waves): each apps-wave-<N> health-gates (wait:true) ONLY its own wave, so a crashloop in a later wave can no longer stall an earlier wave or block new revisions. See DESIGN-waves.md for the wave table + cutover runbook.

TODOs (later phases — do not action in Phase 0)

• Source cutover (WS-GITOPS, Phase 6): base/flux-system.yaml currently points at the bootstrap source. After Gitea is onboarded, repoint spec.url to gitea.home.keithjackson.dev and keep an off-cluster mirror (spec docs/05 "Source-of-truth", CONTRIBUTING.md).
• SOPS decryption (WS-SEC, Phase 1): add spec.decryption.provider: sops (age secret name only, never plaintext) to the platform/apps Kustomizations once the age key is bootstrapped (ADR-0007).
• Split ordered Flux Kustomizations if intra-platform ordering needs to be explicit (e.g. a separate cilium/longhorn Kustomization others dependsOn).