expose-service

name	expose-service
description	Expose a workload for access. Four paths: envoy-internal (LAN via split-horizon DNS), Tailscale Ingress (internal remote HTTP with browser-trusted TLS), Tailscale Service annotation (raw TCP / non-HTTP), envoy-external + Cloudflare tunnel (genuinely public, requires explicit approval). Handles HTTPRoute authoring, DNSEndpoint for secondary domains, and per-domain cert wiring.

Expose a service

Task skill for routing traffic to a workload. Anton has three supported access paths; architecture deep-dive lives in kubernetes/apps/network/CLAUDE.md.

Exposure policy (ADR 0012, amended 2026-04-17)

Pick by who needs to reach the workload, not by what feels easiest:

1. LAN clients only → envoy-internal HTTPRoute. Split-horizon DNS via k8s-gateway returns the internal LB to LAN clients.
2. Off-LAN HTTP admin UI (browser) → Tailscale Ingress (ingressClassName: tailscale + tls.hosts: [<slug>]). The operator provisions a Let's Encrypt cert on <slug>.<tailnet>.ts.net; browsers trust it natively. Recipe A in references/tailscale.md.
3. Off-LAN raw TCP or non-HTTP → Tailscale Service annotation (tailscale.com/expose: "true"). No TLS termination on the proxy — clients reach whatever the backend serves on its target port. Recipe B in references/tailscale.md.
4. LAN clients AND off-LAN HTTP access → envoy-internal HTTPRoute plus a Tailscale Ingress for the same workload. LAN users keep the <app>.${SECRET_DOMAIN} URL; remote ops use <slug>.<tailnet>.ts.net.
5. Genuinely public (audience that cannot be required to join the tailnet) → envoy-external HTTPRoute + Cloudflare tunnel. Requires explicit user approval before authoring.

Do not pick envoy-external to solve "I want to reach this from my laptop off-LAN" — that is what Tailscale is for now (ADR 0012). Shipping something public and pulling it back is irreversible (cached DNS, search engines, external referrers); Tailscale is reversible.

⚠️ Throughput caveat (ADR 0012 amendment). Tailscale proxies default to userspace netstack and on v1.84+ hit upstream bug tailscale/tailscale#16198; SPA payloads over the tailnet run ~12 KB/s from a macOS peer. LAN clients are unaffected. Use Tailscale for off-LAN admin access, not for heavy data paths, until the operator ships 1.98.x. Full context in references/tailscale.md.

Gateway-choice matrix

Use case	Path	Hostname	TLS in browser?	Reaches
LAN only (default)	envoy-internal HTTPRoute	<app>.${SECRET_DOMAIN}	Yes (cert-manager)	LAN → k8s-gateway DNS → cluster
Off-LAN HTTP admin UI	Tailscale Ingress (ingressClassName: tailscale)	<slug>.<tailnet>.ts.net	Yes (Let's Encrypt via MagicDNS)	Tailnet device → operator proxy → Service
Off-LAN raw TCP / non-HTTP	Tailscale Service annotation	<slug>.<tailnet>.ts.net	No (TCP pass-through)	Tailnet device → operator proxy → Service
LAN + off-LAN HTTP	HTTPRoute and Tailscale Ingress	both above	Yes on both	either path resolves independently
Public (requires approval)	envoy-external HTTPRoute	<app>.${SECRET_DOMAIN}	Yes (Cloudflare)	Internet → Cloudflare tunnel → cluster
App on a second domain (${SECRET_DOMAIN_TWO})	envoy-external HTTPRoute	<app>.${SECRET_DOMAIN_TWO}	Yes	also needs an explicit DNSEndpoint — see references/secondary-domain.md

Both envoy gateways live in namespace network. HTTPRoutes must set parentRefs[].namespace: network (cross-namespace) and sectionName: https (attach to the TLS listener, not port 80). Tailscale exposure does not use a Gateway-API HTTPRoute — it uses either a networking.k8s.io/v1 Ingress (Recipe A) or a Service annotation (Recipe B).

No bundling. Tailscale exposure changes ship on their own PR, never mixed with Cilium / gateway / CNI changes (ADR 0012).

Workflow

1. Confirm the path against the exposure policy above. If envoy-external is on the table, verify the user has approved public exposure before writing anything. "I want to reach it off-LAN" is a Tailscale reason, not an envoy-external reason.
2. Author the resource(s):
   • HTTPRoute path (envoy-internal or envoy-external) — write kubernetes/apps/<ns>/<app>/app/httproute.yaml using the template in references/authoring-httproute.md, or use the chart-values variant (Workflow B) if the chart supports it (bjw-s app-template).
   • Tailscale Ingress (Recipe A, HTTP admin UIs) — write an Ingress with ingressClassName: tailscale and tls.hosts: [<slug>]. Prefer the chart's own ingress.* values knob when available. Recipe: references/tailscale.md.
   • Tailscale Service annotation (Recipe B, raw TCP / non-HTTP) — add tailscale.com/expose: "true" and tailscale.com/hostname: <short-slug> to the Service's annotations. Prefer the chart's service.annotations knob over a Kustomize patch. Recipe: references/tailscale.md.
   • Combined (HTTPRoute + Tailscale Ingress) — do both; they are independent and don't conflict. Same-PR bundling of Tailscale work with Cilium / gateway / CNI changes is forbidden (ADR 0012).
3. Wire any new manifest file into kubernetes/apps/<ns>/<app>/app/kustomization.yaml. Annotation-only changes via chart values need no kustomization edit.
4. If the hostname is on a secondary domain (not ${SECRET_DOMAIN}), also add a DNSEndpoint resource and verify the gateway's cert listener covers the domain — see references/secondary-domain.md. Skipping this is the single most common footgun in this skill. (Does not apply to Tailscale — MagicDNS handles its own.)
5. Ship it. If any *.sops.* files are new, run sops -e -i <file> to encrypt. Then commit + push, and task reconcile (or wait for the Flux interval).
6. Verify. Run the checks in references/verify.md; for the Tailscale path, also verify as documented in references/tailscale.md.

Pre-commit checklist

Common:

• Path choice matches policy (LAN-only → internal; off-LAN HTTP → Tailscale Ingress; off-LAN raw TCP → Tailscale annotation; external only when explicitly approved)
• Diff contains Tailscale changes only — no Cilium / gateway / CNI edits in the same commit (ADR 0012)
• No plaintext secrets: any *.sops.* files show encrypted via sops filestatus

HTTPRoute path:

• parentRefs[0].name is envoy-external or envoy-internal (never a Service name)
• parentRefs[0].namespace: network set (cross-namespace attach is required)
• parentRefs[0].sectionName: https set (attach to TLS listener, not port 80)
• backendRefs[].name matches an actual Service in the app's namespace
• HTTPRoute (and DNSEndpoint, if any) listed in app/kustomization.yaml
• If hostname is on ${SECRET_DOMAIN_TWO} → DNSEndpoint resource present
• If a new second-domain cert was added → gateway listener's tls.certificateRefs updated

Tailscale Ingress path (Recipe A):

• ingressClassName: tailscale set; no spec.rules[].host (operator reads tls.hosts)
• tls.hosts[0] is a short slug (no dots, no tailnet name embedded)
• defaultBackend.service points at an actual Service in the app's namespace
• Ingress listed in app/kustomization.yaml (or delivered via chart ingress.* values)
• No real tailnet name committed anywhere (use <tailnet-name>.ts.net placeholder in docs)

Tailscale Service annotation path (Recipe B, non-HTTP / raw TCP only):

• Annotation is on the Service the chart produces, not on a wrapping resource
• tailscale.com/hostname is a short slug (no dots, no tailnet name embedded)
• Workload is genuinely non-HTTP — if it's a browser UI, use Recipe A instead
• No real tailnet name committed anywhere

Canonical in-tree examples

Read the live manifest rather than a frozen copy:

• Public, app-template inline route: values (Workflow B) → kubernetes/apps/default/echo/app/helmrelease.yaml
• Internal, standalone HTTPRoute (Workflow A) → kubernetes/apps/observability/kube-prometheus-stack/app/httproute.yaml
• DNSEndpoint shape (CNAME to tunnel on a secondary domain) → kubernetes/apps/network/cloudflare-tunnel/app/dnsendpoint.yaml

Further reading

Reference	When to read
references/authoring-httproute.md	Writing the HTTPRoute YAML (Workflow A standalone, Workflow B route-in-values)
references/secondary-domain.md	Hostname on ${SECRET_DOMAIN_TWO} or any non-primary domain
references/verify.md	After deploy, or when an HTTPRoute exists but the app is unreachable
references/envoy-gateway.md	Background on the in-cluster gateway controller (Gateway specs, LB IPs, policies)
references/cloudflare-tunnel.md	Background on the public ingress path (cloudflared, http2 transport, origin config)
references/tailscale.md	What Tailscale does — and does not — do in this cluster

Related skills

• Architecture / traffic flow / debug commands → kubernetes/apps/network/CLAUDE.md
• Pattern reference for HelmRelease / ks.yaml → anton-repo-conventions
• Triaging an HTTPRoute that exists but the app is unreachable → debug-flux-reconciliation