home-network-k3s-impl/schemas/renderer-contract.md

Renderer Contract — ServiceDefinition → rendered resources

Status: authoritative Phase-0 interface contract. Consumed by the manifest renderer (WS-GITOPS), the network/egress renderer (WS-NET), storage (WS-STATE), TLS/DNS (WS-EDGE), identity (WS-SEC), observability (WS-OBS), updates (WS-UPD), and the conformance/policy/CI agents (WS-TEST).

Source of truth: spec docs/13-service-catalog.md (the ServiceDefinition schema and default posture). This document maps each field of servicedefinition.schema.json to the concrete resources the platform must render, and cites the requirement each mapping satisfies. Changing this contract is an interface change — coordinate per the spec's agents/coordination-protocol.md (§2).

The renderer MUST first materialize the schema defaults (below), then apply this mapping. A field absent from a ServiceDefinition renders from its default posture, not "not at all."

Default posture (applied before mapping) — docs/13 §"Default posture"

Field	Default	Requirement
kind	container	R-PLAT-02/03
exposure	internal	R-DNS/R-NET
egress	internet	R-NET-05
storage	[] (config PVC still expected for stateful svc)	R-STATE-02
dependencies	[] → reaches only DNS (default-deny)	R-NET-01
inClusterClients	[] → no direct east-west client; only the Gateway may reach an exposed port	R-NET-01/02
auth.mode	forward-auth for any exposed UI	R-IDP-02
update.channel	stable	R-UPD-01
update.autoRollbackOnFailedHealth	true	R-UPD-03
observability.metrics	true	R-OBS-01
observability.metricsEndpoint	absent → the workload serves no Prometheus endpoint; no ServiceMonitor	R-OBS-01
observability.livenessWorkload	the object this SD renders (Deployment named after the service; VirtualMachineInstance for kind: vm)	R-OBS-01
backup of irreplaceable state	off-cluster (never reacquirable)	R-STATE-03

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Field → resource mapping

name

• Renders: the service Namespace (trust zone), Deployment/VM name, Service name, and the DNS label <name>.home.keithjackson.dev.
• Requirements: R-DNS-01 (naming model, docs/09), R-NET (namespace = isolation boundary, docs/03).

kind + source

• container + source.image → Deployment (+ Service) using the image ref.
• vm + source.vmTemplate → KubeVirt VirtualMachine with a CDI-imported root disk.
• The schema enforces exactly-one-of (image for container, vmTemplate for vm).
• Requirements: R-PLAT-02/03 (PaaS/IaaS, docs/13); VM disks inherit Longhorn durability (docs/04).

exposure (internal | public)

• Both classes render an HTTPRoute on the shared Gateway and are reachable on the LAN via internal split-horizon DNS.

• public additionally signals the documented manual edge port-forward of 80/443 (and any service-specific port, e.g. Plex 32400, Minecraft 25565) to the ingress VIP, and a public ExternalDNS record for <name>.home.keithjackson.dev.

• internal renders no public DNS record and is never port-forwarded (PiHole resolves it to the internal Gateway VIP).

• HOW "no public DNS record" IS MADE TRUE, since it was prose only until 2026-09-14. Every HTTPRoute rendered for an internal service carries ExternalDNS's own controller annotation with a value other than the one ExternalDNS claims:

  external-dns.alpha.kubernetes.io/controller: none
  

  ExternalDNS v0.21.0 (source/annotations/processors.go) skips any source object whose controller annotation is present and != "dns-controller", and source/gateway.go applies that check inside Endpoints() before any hostname is resolved — so the route never becomes an endpoint for any name it declares. source/service.go applies the identical check, which covers the second configured source. It is derived from exposure and nothing else (catalog/render.py _externaldns_route_annotations), so the operator's one declaration decides, a service that OMITS exposure inherits the internal default and is likewise unpublishable, and there is no per-service list to forget to extend. ci/render-golden.sh proves apps/ reproduces from catalog/, so an internal service cannot exist in the applied tree without it, and conformance/tests/l0-static/internal-services-publish-no-public-dns re-proves both directions (present on internal, absent on public) on every gate run.

  • The route itself, the wildcard TLS and LAN reachability are unchanged — only the public record is withdrawn. The internal split-horizon answer is Pi-hole's job (R-DNS-03), which is why withdrawing these records requires Pi-hole to be answering the LAN authoritatively first: the zone has no *.home.keithjackson.dev wildcard, and *.keithjackson.dev does not match two labels, so a withdrawn name is a public NXDOMAIN with no fallback.
  • Why not a cluster-wide ExternalDNS opt-in filter (labelFilter, which v0.21.0 supports for both configured sources): seven published names come from hand-authored platform//apps/ manifests that carry no exposure field for a renderer to read, and an opt-in filter deletes all seven the moment it is set. Per-resource exclusion has exactly the blast radius of the defect. The filter stays available as hardening once those seven are adjudicated — see platform/externaldns/helmrelease.yaml and the register in the L0 check.

• public renders the record but the renderer does not yet set a target: the record still resolves to the shared Gateway VIP, i.e. an RFC1918 address, so a public service is not in fact publicly reachable. Fixing that is not a renderer change on v0.21.0 — source/gateway.go reads external-dns.alpha.kubernetes.io/target only from the Gateway (and a ListenerSet), never from an HTTPRoute, so a per-service target override is not expressible while the public services share the shared Gateway. The open decision is recorded in platform/externaldns/helmrelease.yaml.

• Exposure does not relax east-west default-deny (docs/09 §"Interaction with default-deny").

• Requirements: R-DNS-02/03 (docs/09), R-NET-04 (docs/03).

egress (internet | vpn) — egress steering

• internet → pod egress allow to the default WAN route (node → SOHO edge → internet).
• vpn → the pod is steered through the shared in-cluster Gluetun/PIA (WireGuard) egress gateway (Cilium Egress Gateway / routing). The pod gets no independent egress path; the kill-switch (fail-closed) and allow rules are enforced at the gateway + namespace/policy level, outside the workload.
• Requirements: R-NET-05 (egress class), R-NET-06 (VPN kill-switch, mandatory & central). VPN-class set is normative: sonarr, radarr, jackett, qbittorrent (docs/03/13).

dependencies[] (to / port / protocol) — east-west policy

• Each namespace first gets the default-deny baseline (deny all ingress + egress) applied by GitOps at namespace creation, with a standing allow only for DNS to the in-cluster resolver. Observability scraping is NOT in the baseline — it is an additive allow rendered per declared observability.metricsEndpoint (see below), scoped to that one port. This paragraph used to claim the baseline carried a standing monitoring allow; it never did, and an app metrics port would have been dropped by policy even with the Service port and monitor endpoint in agreement.
• Each dependencies[] entry renders one CiliumNetworkPolicy egress allow: this service → to service on port/protocol. Everything undeclared stays denied.
• Empty dependencies ⇒ the service can reach only DNS.
• Requirements: R-NET-01 (default-deny baseline), R-NET-02 (explicit allow / deny undeclared). Auditable via Hubble (R-SEC-03, R-OBS-04).

storage[] (name / size / class / mountPath / export / subPath / readOnly) — PVs + PVCs

• class: longhorn → a PVC on the 3-replica Longhorn StorageClass sized by size (replicated config/DB/app state), ReadWriteOnce, dynamically provisioned. For a vm, the disk is a Longhorn volume via CDI.
• class: bulk → a static, pre-bound external NFS PersistentVolume and its PVC. The entry's export is the absolute path on the bulk server; the SERVER is never named in a ServiceDefinition — it is the ${BULK_NFS_SERVER} cluster-vars knob, so one authored definition promotes across environments that reach the same storage by different addresses (R-ENV-02). Not 3× replicated: durability is the storage host's ZFS pool, not Longhorn.
  • storageClassName: "" on both PV and PVC (explicitly empty ⇒ statically provisioned; no provisioner is ever asked to create anything, and the default-StorageClass annotation is suppressed). Deliberately NOT the bulk StorageClass: a StorageClass provisioner is immutable, so re-pointing that stub would make Flux fail permanently on it.
  • Binding is pinned from both ends — claimRef on the PV, volumeName on the PVC — so no other claim of matching size/mode can win a race for the volume.
  • persistentVolumeReclaimPolicy: Retain, always. Bulk data pre-exists the cluster, is far larger than the cluster, and may have consumers outside it; nothing here may reclaim it.
  • Access mode follows the read/write posture and is always …Many, because one export is consumed by several namespaces and several nodes at once: ReadOnlyMany when readOnly, ReadWriteMany otherwise. ReadWriteOnce cannot express either.
  • mountOptions are a platform decision held in the renderer, not a per-service field: nfsvers=4.1,hard,noatime,timeo=600,retrans=2. NFSv4 carries mount and lock in-protocol, so the only port that must be reachable is tcp/2049 — no rpcbind/111, mountd or statd, which is what keeps the firewall surface to a single rule. hard is chosen over soft because a soft mount converts a server hiccup into a short read handed to the application.
  • size on a bulk entry is the PV's advertised capacity and nothing more — no component enforces it (the ZFS pool is the real limit), so it should state the dataset's actual size so kubectl get pv reports something true.
  • fsGroup does not apply. The in-tree NFS volume plugin performs no ownership management, so podSecurityContext.fsGroup is a no-op on a bulk volume. A bulk mount that must be written therefore requires the container's own uid/gid to be one the export's ownership permits (e.g. Plex's PLEX_UID/PLEX_GID, LinuxServer images' PUID/PGID) — or a server-side squash. A mount that succeeds but cannot write is the characteristic failure of this tier.
• mountPath (any class) overrides the /data/<name> default verbatim.
• subPath (any class) mounts a subtree instead of the volume root. Two subPath mounts of one export are two separate mounts, so link() between them fails EXDEV; a workload that needs hardlinks or atomic moves between two directories (Sonarr/Radarr importing from a download path into a library) must mount their common ancestor once instead.
• readOnly (any class) marks the volumeMount read-only, and on a bulk entry also sets the PV's nfs.readOnly so the kernel mount really is ro. Note this is a client-side guarantee: one export serving both a reader and a writer that may land on any node cannot distinguish them server-side.
• State separation rule: anything that must survive a rebuild lives on a named volume here, never on ephemeral fs/hostPath — so the workload can be destroyed and re-applied from git with data intact.
• Requirements: R-STATE-01 (rebuild survival), R-STATE-02 (Longhorn replication), R-STATE-04 (bulk tier). (docs/04)

hardware (gpu) — host device capability

• The field is INTENT, never MECHANISM. hardware.gpu is an enum of capability classes (today: intel-quicksync), not a device path, not a hostPath, not a resource request. The ServiceDefinition says what class of host device this workload needs; how the platform hands it over is catalog/render.py's business and lives nowhere else. Do not "simplify" this into a raw /dev/... path. The entire payoff is that migrating from the hostPath mechanism below to the Intel GPU device plugin (resources.limits: gpu.intel.com/i915) is a renderer change with zero catalog edits and zero re-review of per-service device wiring. Extend the enum for a genuinely different capability class (e.g. nvidia-nvenc); never to name a second route to the same one.

• gpu: intel-quicksync → on the app container only (never a sidecar), exactly two things:

  1. a hostPath volume dri → /dev/dri, type: DirectoryOrCreate;
  2. a read-write volumeMount of dri at /dev/dri on the app container (VA-API opens the render node read-write, so it is deliberately not readOnly).

  Mounting the device is sufficient. That is the whole mapping.

• podSecurityContext.supplementalGroups is deliberately NOT rendered, and adding it would be a regression rather than a hardening. /dev/dri/renderD128 is root:render 0660, so the obvious move is to push the host render GID in — and it does not work. Measured in the running container on prod-2, 2026-09-30: the image's own /etc/cont-init.d/45-plex-hw-transcode-and-connected-tuner hook finds every char device under /dev/dri, stat -c '%g' each one's GID, groupadds a matching group inside the container when none exists, and usermod -a -G the app user into it — every start, nothing hardcoded. cont-init.d completes before services.d, so the account database is already correct when the service execs. The service then starts via exec s6-setuidgid plex …, and s6-setuidgid replaces the process group list from /etc/group rather than appending to it: Plex Media Server runs as Uid: 1000 Gid: 1000 Groups: 100 1000, with root's gid 0 — which PID 1 (s6-svscan) does hold — gone. A Kubernetes supplementalGroups therefore reaches s6-svscan and is discarded before the app ever starts. It would be inert and it would mislead whoever debugs this next. The renderer asserts its own absence in render.py --selftest.

  • A corollary worth having: because the hook re-stats the device on every start, the host GID drifting (a node rebuild renumbering the systemd dynamic render group) is self-healing. No GID is pinned anywhere in this repo.
  • Scope of that measurement, stated so nobody over-reads it. "Mounting the device is sufficient" was established for an image that resolves the device group itself. A FUTURE consumer that runs non-root and has no equivalent init hook would still need the group solved somehow — and the answer for that case is a renderer change (per-image handling, or the device plugin), not a new ServiceDefinition field. The enum is what keeps that option open. The first such consumer must re-measure rather than assume this bullet covers it.

• DirectoryOrCreate is load-bearing — do not tighten it to Directory. A node that comes back without the render device (rebuild, BIOS change, driver regression, hardware swap) must degrade the workload to software transcoding, not fail the mount. apps-wave-0 is wait: true and apps-wave-1 dependsOn it, so a failed hostPath mount stalls the whole app tier for the sake of a feature that is not load-bearing. /dev is tmpfs, so the empty directory the kubelet creates on such a node leaves nothing durable behind.

  • The cost of that choice, stated plainly: a missing device is silent. The workload software-transcodes and nothing reports it. There is no metric to alert on — media apps here render no metricsEndpoint, so no ServiceMonitor exists — and an alert that cannot fire is worse than none (see §observability's 2026-09-13 correction). The only proof of hardware transcode is an operator observing it in the application's own dashboard.

• Deliberately NOT rendered from this field: no privileged: true (Kyverno restrict-host-namespaces is Enforce on app namespaces and would reject it, and the render node does not need it); no nodeSelector (placement is a separate concern with its own justification — this field is about the device, not about where the pod lands); no resource requests/limits (there is no app-container resource render path, and inventing one here would be scope creep).

• Absent ⇒ nothing at all is rendered; every service that does not opt in stays byte-identical. Ignored for kind: vm — a VM receives devices through KubeVirt's own domain.devices.

• Requirements: R-PLAT-02 (the PaaS provides the host capability; the app declares need).

ingressRoutes[] (host / port) — HTTPRoute + Certificate + DNS

• Each entry renders an HTTPRoute attaching host → the service port on the shared Gateway.
• TLS: the Gateway terminates with the cert-manager wildcard *.home.keithjackson.dev certificate (Let's Encrypt via DNS-01, scoped Cloudflare token), so no per-service cert step — trusted, non-self-signed, auto-renewed, including for internal services. Per-service Certificate only where isolation warrants.
• DNS: ExternalDNS watches the HTTPRoute and manages the <host> record — but only for a public service. An internal service's route is rendered with ExternalDNS's controller annotation set to none, which removes it from ExternalDNS's view entirely (see §exposure), so its <host> exists only in the internal split-horizon answer PiHole serves, never in the public zone. A public record's TARGET is still the Gateway VIP, not a routable address — open operator decision, see §exposure.
• The host pattern is enforced to <label>.home.keithjackson.dev by the schema.
• Requirements: R-TLS-01/02/03 (docs/08), R-DNS-01/02/03 (docs/09).

inClusterClients[] (namespace / port / protocol / name) — direct east-west clients

• Each entry renders ONE CiliumNetworkPolicy ingress allow on this service: endpointSelector = this service, fromEndpoints matching only the reserved k8s:io.kubernetes.pod.namespace: <namespace> label, toPorts carrying only the declared port/protocol. Name: <service>-allow-<name>-ingress, name defaulting to namespace.
• Why the field exists. ingressRoutes opens the north-south path only (the gateway allow admits fromEntities: [ingress], the Gateway proxy identity, and nothing else), and dependencies compiles edges only between catalog services — both halves come from a catalog entry's own declaration. A platform controller that dials this service's ClusterIP directly was therefore unauthorable, and under default-deny it is dropped. Prod hit exactly that: its GitRepository points at the in-cluster Gitea Service (http://gitea.gitea.svc.cluster.local:3000/..., clusters/prod/kustomization.yaml) so GitOps depends on no public DNS/Cloudflare/Gateway/${BASE_DOMAIN}, but flux-system's source-controller was denied — and the HTTPRoute that would have served a public name lives in a downstream tier that cannot apply while the source is down (source down → routes never rename → source stays down).
• Least privilege is part of the contract: a namespace and a port, never fromEntities: all, never a port-less allow. The client is selected by namespace rather than pod labels because an upstream controller's labels are its chart's to change, not this platform's contract — so name a platform-controller namespace whose entire membership may hold that reach, never a shared one.
• Additive, and not a dependency: the namespace default-deny baseline is unchanged (ingress: []), every undeclared source/port stays denied, and the entry creates no wave ordering edge — the client is a platform component, not a catalog service.
• Requirements: R-NET-01 (default-deny baseline stands), R-NET-02 (explicit allow / deny undeclared), R-GITOPS-02 (the allowance is authored in the one reviewable object rather than surviving as a live-applied cluster object). Auditable via Hubble (R-SEC-03, R-OBS-04).

auth (mode / groups[]) — identity integration (Keycloak / oauth2-proxy)

• oidc → register the app as a Keycloak OIDC client (declarative realm/client config, GitOps; client secret SOPS-encrypted). App does its own login redirect.
• forward-auth → protect the service's ingressRoutes at the Gateway with oauth2-proxy → Keycloak so auth happens before traffic reaches the app (bare UIs without usable OIDC).
• native → no platform SSO wiring; app owns its auth (documented exception, e.g. Plex/Seerr; and Keycloak itself as the IdP, admin login local + MFA).
• none → no auth wiring (internal-only, discouraged).
• groups[] → the Keycloak groups permitted access, enforced by the OIDC client mappers / oauth2-proxy allowed_groups. Schema requires ≥1 group for oidc/forward-auth — access is "in an authorized group," not merely "logged in."
• Keycloak, oauth2-proxy, and app→Keycloak / proxy→Keycloak / Keycloak→DB flows are ordinary workloads under default-deny with explicit allows (ties back to dependencies).
• Requirements: R-IDP-02 (protect OIDC-capable and bare UIs), R-IDP-06 (group-based authorization). (docs/15, ADR-0014)

update (channel / range / cadence / autoRollbackOnFailedHealth / pin)

• container kind → a Flux ImagePolicy (+ ImageRepository) encoding channel/range; Flux image-automation advances the running version on its scan interval (cadence). pin freezes the service (stops automation). No human/AI edits a tag.
• vm kind → in-guest unattended package updates on cadence (cloud-init), per docs/11 §3.
• autoRollbackOnFailedHealth: true → health-gated rollout that reverts on failed health and alerts.
• Requirements: R-UPD-01 (stable only), R-UPD-02 (no human/AI authoring), R-UPD-03 (health-gated auto-rollback). (docs/11, ADR-0009)

observability (metrics / slis[] / metricsEndpoint / livenessWorkload) — ServiceMonitor + alerts

• metrics: true → the platform collects signals for this service: logs to Loki via the node agent, and kube-state-metrics readiness for the up SLI below. Both are platform-wide scrapes; neither needs a per-service CR. It does not assert that the workload serves a Prometheus endpoint. (Corrected 2026-09-13. It used to render a ServiceMonitor unconditionally, hardcoded to a Service port named metrics. No rendered Service ever defined such a port, so all twelve app monitors discovered ZERO targets — verified on prod: 24 jobs in up, not one of the twelve — and every up{job=...} SLI built on them was structurally inert. metrics: true could not have been right: Plex, Pi-hole, Jackett, qBittorrent, Sonarr, Radarr, Seerr, Semaphore and Nextcloud serve no Prometheus endpoint at all without a separate exporter.)
• metricsEndpoint: {port, name?, path?, interval?} → the workload does serve metrics, here. Renders all three halves of a working scrape from the one declaration, because any one of them missing makes the scrape silently yield nothing:
  1. a named Service port (name, default metrics) on that port;
  2. a ServiceMonitor endpoint selecting that port name, on path at interval;
  3. a CiliumNetworkPolicy admitting the monitoring namespace to that port — the namespace default-deny baseline is ingress: [], so without it the scrape is dropped by policy. The metrics port is deliberately not added to the Gateway ingress allow: it is east-west for Prometheus, never north-south.
• each entry in slis[] → at least one alert rule routed by Alertmanager to email; a per-service Grafana dashboard row. up → a <name>-down critical alert reading the readiness of livenessWorkload from kube-state-metrics (kube_deployment_status_replicas_available, kube_statefulset_status_replicas_ready, kube_daemonset_status_number_available) or, for a VirtualMachineInstance, the existence of kubevirt_vmi_info{phase="running"}. Each rule carries an or absent(...) half, so the signal DISAPPEARING fires the alert rather than silencing it.
• livenessWorkload: {kind, name} → which object's readiness is this service. Defaults to the object this SD renders; override it when the running workload is a different one (keycloak's server is a StatefulSet owned by the Keycloak operator — a Deployment-shaped rule would absent() and fire forever).
• Requirements: R-OBS-01 (per-service SLIs/alerts). Platform-health alerts (R-OBS-04) are rendered platform-wide, not per ServiceDefinition. (docs/10)

backup (policy)

• a schedule ref (e.g. daily-offcluster) → Velero + Longhorn off-cluster backup schedule for this service's volumes/namespace.
• literal reacquirable → no 1:1 backup (bulk media only). Irreplaceable state (configs, DBs, Nextcloud, Gitea, PiHole config, Keycloak DB) MUST NOT be reacquirable.
• Requirements: R-STATE-03 (off-cluster DR backup). (docs/04)

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Cross-field invariants the renderer / L0-L1 tests rely on

1. kind ↔ source: container⇒image, vm⇒vmTemplate (schema-enforced).
2. auth ↔ groups: oidc/forward-auth ⇒ non-empty groups (schema-enforced; R-IDP-06).
3. default-deny is unconditional: every namespace gets the deny baseline regardless of dependencies; dependencies only adds allows (R-NET-01/02). The same holds for inClusterClients: it adds one namespace+port ingress allow and never relaxes the baseline.
4. egress is enforced outside the workload: vpn renders gateway steering + kill-switch, never a per-service sidecar the app could bypass (R-NET-05/06).
5. TLS is never self-signed and needs no per-service step: the wildcard Gateway cert covers every ingressRoutes.host, internal included (R-TLS-01/03).
6. irreplaceable ⇒ off-cluster backup: DR-critical services must not carry backup.policy: reacquirable (R-STATE-03). (Advisory: not enforced by the schema — an L0 policy check should assert it; see "Ambiguities / escalations" in schemas/README.md.)
7. exposure: internal ⇒ no public DNS record, structurally. Every HTTPRoute rendered for an internal service (including one that omits exposure and takes the default) carries external-dns.alpha.kubernetes.io/controller: none, and no public service's route carries it. Derived from exposure alone; enforced on every gate run by conformance/tests/l0-static/internal-services-publish-no-public-dns (R-DNS-03).
8. hardware is inert until opted into, and its mechanism is renderer-local. An SD with no hardware key renders no volume and no volumeMount; an SD with it gains no securityContext either. Both directions are proven by render.py --selftest. The /dev/dri hostPath and the DirectoryOrCreate type appear in catalog/render.py and nowhere else, so the capability's implementation can be replaced without touching a single ServiceDefinition.

Requirement traceability (contract-level)

Primary R-GITOPS-02 (single reviewable object wires every requirement). Field-level: R-NET-01/02 (dependencies, inClusterClients), R-NET-05/06 (egress), R-STATE-01/02/04 (storage), R-STATE-03 (backup), R-TLS-01/02/03 + R-DNS-01/02/03 (ingressRoutes + exposure), R-OBS-01 (observability), R-UPD-01/02/03 (update), R-IDP-02/06 (auth), R-PLAT-02/03 (kind/source).