feat(dns): publish Gateway names to the WAN via in-cluster DDNS
Gateway-published records now CNAME to wan.${BASE_DOMAIN}, which a
favonia/cloudflare-ddns Deployment keeps at the home WAN's current public
IP. Operator decision: every Gateway-published name goes public; internal
services (controller: none) remain unpublished.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
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---
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date: 2026-10-03
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branch: feat/public-dns-wan-target
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title: Public DNS now points at the WAN — Gateway-published names CNAME to an in-cluster DDNS record
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---
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## What changed
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The operator closed the open "public-target gap" recorded in
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`platform/externaldns/helmrelease.yaml`. The WAN NAT / port-forwarding (80/443 → Gateway VIP
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192.168.2.20) was done by the operator outside this repo.
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Operator decisions (2026-10-03):
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1. **Scope: every Gateway-published name goes public.** That covers the five `exposure: public`
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apps (plex, gitea, keycloak, nextcloud, seerr) and also the hand-authored admin UIs (auth,
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crafty, grafana, headlamp, the `home.keithjackson.dev` apex). `internal` services still publish
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nothing: their `controller: none` route annotation is checked before the target is read.
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2. **The WAN IP is kept current in-cluster**, not hardcoded.
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Implementation:
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- `platform/gateway/gateway.yaml`: `external-dns.alpha.kubernetes.io/target: wan.${BASE_DOMAIN}` on
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the shared Gateway. Every gateway-sourced record changes from `A 192.168.2.20` to
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`CNAME wan.home.keithjackson.dev`.
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- `platform/externaldns/ddns.yaml` (new): `favonia/cloudflare-ddns:1.17.1` Deployment in the
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`external-dns` namespace. It reuses `cloudflare-api-token` and keeps `wan.${BASE_DOMAIN}` an
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unproxied IPv4 A record at the WAN IP (detected via Cloudflare trace, checked every 5 min,
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`DELETE_ON_STOP=false`). external-dns has no TXT registry entry for it, so it never owns or
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deletes it.
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- The helmrelease comment block and the README now describe the decision instead of the gap.
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Known consequence: **k3s nodes resolve through public DNS** (`node_baseline_dns_servers` = 8.8.8.8 /
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1.1.1.1). The kube-apiserver's OIDC issuer `keycloak.home.keithjackson.dev` therefore resolves to the
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WAN IP from the nodes, and kubectl SSO works only if the router hairpins WAN:443 back to the Gateway.
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A LAN-side probe of `136.51.115.252:443` on 2026-10-03 returned a **self-signed placeholder cert**,
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not the Gateway's Let's Encrypt wildcard. That suggests no hairpin. The cert-based admin kubeconfig
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is unaffected.
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## What I verified
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- Live prod, 2026-10-03, before the change: Gateway `gateway/shared` ADDRESS `192.168.2.20`.
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External-dns args include `--source=gateway-httproute --source=service --policy=sync
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--txt-owner-id=prod --domain-filter=keithjackson.dev`, and it logs "All records are already up to
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date".
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- Public answers at 1.1.1.1: plex/gitea/keycloak/grafana/auth/apex → `192.168.2.20`;
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`crafty-mc` → `.22` and `unifi` → `.21` (service source, not affected by this change); jackett →
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none (internal, correctly unpublished).
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- The authority (betty.ns.cloudflare.com) has no unprefixed TXT, AAAA or MX at `plex.` or the apex,
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so the A→CNAME switch has no co-existing record to collide with.
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- WAN IP from the workstation: `136.51.115.252`.
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- No CiliumNetworkPolicy or NetworkPolicy in `external-dns`. The Kyverno label and default-deny
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policies match only `app-namespace` namespaces. The vpn egress policy selects only
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`egress-class: vpn` pods.
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- Toolbox gate result: see the PR description (run after this commit).
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## What I did NOT verify
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- **The outside-in path.** I have no vantage point outside the LAN. Whether
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`https://<svc>.home.keithjackson.dev` from the internet reaches the Gateway with the LE cert is
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UNVERIFIED.
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- **Hairpin / kubectl SSO after the flip.** Likely broken per the probe above. Fix candidates: a
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node `/etc/hosts` pin for `keycloak.${BASE_DOMAIN}` → Gateway VIP via `node_baseline`, or router
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NAT reflection.
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- **The record-type flip itself**, until Flux reconciles: whether Cloudflare accepts external-dns's
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create-CNAME in the same batch as the delete-A, or converges one interval later.
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- `favonia/cloudflare-ddns` under this pod securityContext. The README warns that
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`no-new-privileges` misbehaves on some Proxmox-style hosts. These are bare-metal nodes, but it is
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untested until the pod runs.
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- Whether the L4 service-source names (crafty-mc, unifi) should also go public. Not decided, not
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changed.
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- `conformance/tests/l0-static/internal-services-publish-no-public-dns/check.sh` header lines 39–40
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still describe the target as open. That is a sensitive path, so it is left for a follow-up.
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@@ -20,6 +20,30 @@ A wildcard `*.keithjackson.dev` matches only one label deep, so `<svc>.home.keit
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its own record. **`internal` services need NO public record** — PiHole resolves them to the internal
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Gateway VIP (split-horizon). ExternalDNS manages **`public`** services' records only.
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## Public target + in-cluster DDNS (2026-10-03)
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Gateway-published records are **CNAMEs to `wan.home.keithjackson.dev`**, not the Gateway VIP:
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```
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plex.home.keithjackson.dev CNAME wan.home.keithjackson.dev <- external-dns (Gateway `target` annotation)
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wan.home.keithjackson.dev A <current WAN IP> <- cloudflare-ddns (ddns.yaml), every 5m
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```
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- The `target` annotation is on the **shared Gateway** (`platform/gateway/gateway.yaml`), so it
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applies to every route that publishes at all. `internal` routes (`controller: none`) still publish
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nothing.
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- `ddns.yaml` runs `favonia/cloudflare-ddns` in this namespace with the same `cloudflare-api-token`.
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It detects the WAN IP through Cloudflare's trace endpoint, so the pod **must not** carry
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`egress-class: vpn`.
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- LAN and pods resolve `*.home.keithjackson.dev` to the Gateway VIP via PiHole and CoreDNS
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(split-horizon) and never use the public path.
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- **Nodes resolve through public DNS** (`node_baseline_dns_servers`), so from a node, the apiserver's
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OIDC issuer `keycloak.home.keithjackson.dev` resolves to the WAN IP. kubectl SSO therefore relies on
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the router hairpinning (NAT reflection) WAN:443 back to the Gateway.
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Check: `dig +short @1.1.1.1 plex.home.keithjackson.dev` → `wan.home.keithjackson.dev.` then the WAN IP;
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`kubectl -n external-dns logs deploy/cloudflare-ddns`.
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## Secrets
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Cloudflare API token referenced **by name** (`cloudflare-api-token`, shared with cert-manager),
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@@ -0,0 +1,87 @@
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---
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# In-cluster dynamic DNS for the home WAN (2026-10-03).
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#
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# Keeps ONE record, `wan.${BASE_DOMAIN}` (A, IPv4 only, not proxied), pointed at the home WAN's
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# current public IP. Every public name external-dns publishes from the shared Gateway is a CNAME to
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# it (platform/gateway/gateway.yaml `external-dns.alpha.kubernetes.io/target`), so a WAN IP change
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# moves all of them through this one record, with no Git change and no external-dns involvement.
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#
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# OWNERSHIP SPLIT WITH EXTERNAL-DNS. This record carries no external-dns TXT registry entry, so
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# external-dns (policy: sync, owner `prod`) never treats it as its own and never deletes it.
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# Conversely this updater manages only the names in DOMAINS and never touches external-dns's records.
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#
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# IP DETECTION. Default `cloudflare.trace`: an HTTPS request to Cloudflare's trace endpoint, which
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# reports the address the request arrived from. Correct here only because this pod is NOT in the
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# `vpn` egress class — the CiliumEgressGatewayPolicy (platform/vpn-egress) selects pods by
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# `homelab.keithjackson.dev/egress-class: vpn` alone, cluster-wide. Labelling this pod `vpn` would
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# publish the VPN exit IP instead of the WAN IP.
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#
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# TOKEN. Reuses this namespace's `cloudflare-api-token` (same Zone:DNS:Edit token as external-dns
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# and cert-manager) — no new secret.
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#
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# TIER NOTE. This lives in the gating `platform` Flux Kustomization (wait: true) next to
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# external-dns. If it ever crashloops, `platform` goes not-Ready and apps stop reconciling (no
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# outage). Kept here rather than in its own non-gating Kustomization to avoid a clusters/** change.
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: cloudflare-ddns
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namespace: external-dns
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labels:
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app.kubernetes.io/name: cloudflare-ddns
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spec:
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replicas: 1 # exactly one writer for the record
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revisionHistoryLimit: 3
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strategy:
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type: Recreate # never two updaters at once
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selector:
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matchLabels:
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app.kubernetes.io/name: cloudflare-ddns
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template:
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metadata:
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labels:
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app.kubernetes.io/name: cloudflare-ddns
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spec:
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automountServiceAccountToken: false
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securityContext:
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runAsNonRoot: true
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runAsUser: 1000
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runAsGroup: 1000
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seccompProfile:
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type: RuntimeDefault
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containers:
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- name: cloudflare-ddns
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image: favonia/cloudflare-ddns:1.17.1
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imagePullPolicy: IfNotPresent
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env:
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- name: CLOUDFLARE_API_TOKEN
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valueFrom:
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secretKeyRef:
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name: cloudflare-api-token
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key: api-token
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- name: DOMAINS
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value: "wan.${BASE_DOMAIN}"
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- name: IP6_PROVIDER
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value: "none" # IPv4 WAN only; leaves any AAAA alone
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- name: PROXIED
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value: "false" # DNS-only: Plex/Gitea/etc. terminate TLS on the Gateway
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- name: UPDATE_CRON
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value: "@every 5m"
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- name: DELETE_ON_STOP
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value: "false" # a pod restart must not blank the record every CNAME depends on
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- name: RECORD_COMMENT
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value: "managed by k3s cloudflare-ddns (platform/externaldns/ddns.yaml)"
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- name: EMOJI
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value: "false"
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resources:
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requests:
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cpu: 5m
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memory: 16Mi
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limits:
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memory: 64Mi
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securityContext:
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allowPrivilegeEscalation: false
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readOnlyRootFilesystem: true
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capabilities:
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drop:
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- ALL
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@@ -81,38 +81,29 @@ spec:
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# what this instance can see or own; per-resource exclusion only ever REMOVES an object from
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# this instance's view, so it cannot make prod capable of deleting a record it does not own.
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# ---------------------------------------------------------------------------------------------
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# THE PUBLIC-TARGET GAP — STILL OPEN, AND NOT FIXABLE HERE ON v0.21.0 (operator decision)
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# THE PUBLIC TARGET — DECIDED 2026-10-03 (operator): every Gateway-published name goes public
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#
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# The five `exposure: public` services (plex, gitea, seerr, keycloak, nextcloud) publish records
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# that point at 192.168.2.20 — the Gateway VIP, an unroutable RFC1918 address — so they are not
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# actually reachable from the internet either. Their records are LEFT EXACTLY AS THEY ARE by
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# this change, for two independent reasons:
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# Until 2026-10-03 every gateway-sourced record answered with the Gateway VIP (192.168.2.20,
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# RFC1918), so nothing published here was reachable from the internet. Two facts constrained the
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# fix, and both still hold:
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# * `external-dns.alpha.kubernetes.io/target` is read in v0.21.0's gateway-httproute source ONLY
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# from the GATEWAY (source/gateway.go: `overrides: annotations.TargetsFromTargetAnnotation(
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# gw.Annotations)`) and from a ListenerSet listener — NEVER from an HTTPRoute. A target on the
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# shared Gateway therefore moves EVERY gateway-sourced record at once.
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# * The home WAN IP is residential and can change, so a literal IP in Git would rot.
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#
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# 1. THE VALUE IS NOT ESTABLISHED. The one public IP this repo knows is 136.51.115.252
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# (clusters/prod/kustomization.yaml, where the zone's `*.keithjackson.dev` wildcard also
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# points). It belongs to the LEGACY non-k3s stack and currently serves a placeholder
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# certificate. Whether prod's public services belong behind it, behind a new forward, or
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# are not meant to be public at all is an operator decision. Breaking five services' DNS
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# on a guess is worse than leaving a known-wrong-but-stable state.
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# 2. THE MECHANISM CANNOT BE SCOPED TO THEM. `external-dns.alpha.kubernetes.io/target` is a
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# real override, but in v0.21.0's gateway-httproute source it is read ONLY from the
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# GATEWAY (source/gateway.go: `overrides: annotations.TargetsFromTargetAnnotation(
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# gw.Annotations)`) and from a ListenerSet listener — NEVER from the HTTPRoute. So there is
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# no per-service target override while every public service shares the `shared` Gateway.
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# Annotating the Gateway would move EVERY gateway-sourced record, which after this change
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# still includes auth, crafty, grafana, headlamp and the apex — i.e. it would publish a
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# routable address for admin UIs. That is strictly worse than the status quo.
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#
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# SO THE DECISION THE OPERATOR OWNS IS TWO-PART, and no knob is added here until the first half
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# is answered, because a knob that cannot take effect invites someone to set it and expect one:
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# (a) WHAT address should the five public names answer with — 136.51.115.252 as-is, a new
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# port-forward/WAN address, or nothing (drop `exposure: public` to `internal` instead)?
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# (b) HOW should they be separated from the non-public names that share the Gateway? Options,
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# roughly in ascending cost: a SECOND Gateway (or a ListenerSet) carrying the target
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# annotation, with only the public services' routes attached; or publishing the five names
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# from the `crd` source (DNSEndpoint objects the renderer emits for `public` services),
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# which restores per-service targeting without a second Gateway.
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# Only (b) is a manifest change; (a) is a fact about the home WAN that has to be checked.
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# The operator's answers: (a) yes, ALL of them — the five `exposure: public` apps AND the admin
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# UIs (auth, crafty, grafana, headlamp, the apex), which sit behind Keycloak / oauth2-proxy;
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# (b) the address is kept current IN-CLUSTER. Implementation:
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# * platform/gateway/gateway.yaml sets `target: wan.${BASE_DOMAIN}` on the shared Gateway, so
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# each published name becomes a CNAME to that one hostname;
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# * platform/externaldns/ddns.yaml (favonia/cloudflare-ddns) keeps `wan.${BASE_DOMAIN}` an A
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# record at the current WAN IP. That record has no external-dns TXT registry entry, so this
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# instance never owns or garbage-collects it.
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# Internal services are unchanged: their routes carry `controller: none` (above), which is
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# checked BEFORE the target is read, so they still publish nothing. The `service` source (the L4
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# LoadBalancers crafty-mc, unifi) does not read the Gateway's annotation and still publishes its
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# LB VIP. Whether those should go public is a separate, still-open question.
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# ---------------------------------------------------------------------------------------------
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# CROSS-CLUSTER DNS OWNERSHIP. Read before changing either knob below.
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#
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@@ -8,3 +8,5 @@ resources:
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# SOPS-encrypted Cloudflare token (env CF_API_TOKEN) — SAME token as cert-manager, second copy in
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# the external-dns namespace. Flux decrypts at reconcile.
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- cloudflare-api-token.sops.yaml
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# DDNS for `wan.${BASE_DOMAIN}` — the CNAME target every Gateway-published record points at.
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- ddns.yaml
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@@ -7,6 +7,23 @@ kind: Gateway
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metadata:
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name: shared
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namespace: gateway
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annotations:
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# PUBLIC DNS TARGET (2026-10-03, operator decision). Without this, external-dns publishes every
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# route on this Gateway with the Gateway's OWN address (${GATEWAY_VIP}, RFC1918), which is
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# unreachable from the internet. With it, every published `<svc>.${BASE_DOMAIN}` (and the apex)
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# becomes a CNAME to `wan.${BASE_DOMAIN}`, an A record that platform/externaldns/ddns.yaml keeps
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# pointed at the home WAN's current public IP. The WAN forwards 80/443 to ${GATEWAY_VIP}.
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#
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# Scope is EVERY route on this Gateway that publishes at all — the operator chose to make the
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# admin UIs (auth, grafana, headlamp, crafty, apex) publicly resolvable alongside the five
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# `exposure: public` apps. `internal` services stay unpublished via their
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# `external-dns.alpha.kubernetes.io/controller: none` route annotation, which external-dns checks
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# BEFORE it reads this target. external-dns v0.21.0 reads `target` from the Gateway only, never
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# from an HTTPRoute — see platform/externaldns/helmrelease.yaml.
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#
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# LAN and in-cluster clients are unaffected: PiHole and CoreDNS answer ${BASE_DOMAIN} with
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# ${GATEWAY_VIP} directly (split-horizon), so they never take this public path.
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external-dns.alpha.kubernetes.io/target: "wan.${BASE_DOMAIN}"
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spec:
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gatewayClassName: cilium
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listeners:
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Reference in new issue
Block a user