feat(trmnl): serve the device endpoint over TLS

The cleartext LoadBalancer was justified with "the firmware cannot be
handed the internal CA". There is no internal CA in that path:
letsencrypt-cluster solves DNS-01 against the renner.uno Cloudflare zone,
so a LAN-only name gets a publicly-trusted certificate without ever being
publicly reachable — which is why trmnl.renner.uno has always served an
issuer CN=YR2 cert.

trmnl-device.renner.uno therefore moves onto Traefik with its own
Ingress, and API_URI follows it to https so the image_url handed back on
/api/display is fetched over the same scheme the device polls with. The
name moves rather than being duplicated: external-dns runs --policy=sync
and would flap the record between the Traefik VIP and the LB address if
both an Ingress and the Service claimed it.

The LoadBalancer stays, without a hostname. http://10.2.99.89 remains a
path to /api/setup that depends on neither Traefik nor cert renewal, and
the captive portal takes a bare address, so it is the recovery route if
TLS is ever what breaks the panel.

Note Traefik's web entrypoint carries a global http -> websecure
redirect, so http://trmnl-device.renner.uno now answers 308 rather than
serving. The device is provisioned with the https URL.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

kubernetes/apps/trmnl/device-ingress.yaml

@@ -0,0 +1,52 @@
+# Device-facing endpoint, over TLS.
+#
+# This replaces the reason the cleartext LoadBalancer in device-service.yaml
+# was given a hostname at all. That file claimed the firmware "would reject
+# the internal CA" — but nothing here is signed by an internal CA:
+# letsencrypt-cluster solves DNS-01 against the renner.uno Cloudflare zone,
+# so trmnl.renner.uno already serves a public Let's Encrypt certificate
+# (issuer CN=YR2) that any client with a normal CA bundle trusts. A
+# LAN-only name gets the same treatment — DNS-01 never needs the host to be
+# publicly reachable — so the device can speak HTTPS like everything else.
+#
+# The hostname moves here from the Service's external-dns annotation rather
+# than being duplicated: two sources claiming trmnl-device.renner.uno would
+# have external-dns flapping the record between the Traefik VIP and the
+# device LB. The LoadBalancer keeps its address and stays reachable at
+# http://10.2.99.89 as a nameless fallback if TLS ever turns out to be the
+# thing that breaks.
+#
+# CONSEQUENCE, and the reason API_URI in terminus.yaml changes with this:
+# Traefik's `web` entrypoint carries a global http -> websecure redirect
+# (helmrelease.yaml: `to: websecure, scheme: https, permanent: true`), so
+# once this name points at Traefik, http://trmnl-device.renner.uno answers
+# 308 rather than serving. Whether the firmware follows that is not
+# documented, so the device is provisioned with the https URL and Terminus
+# hands back https image_urls to match. No mixed-scheme fetch.
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: terminus-device
+  namespace: trmnl
+  # No external-dns hostname annotation: external-dns-unifi runs with
+  # --source=ingress, so it registers the hosts in spec.rules on its own.
+  # Same as the terminus Ingress next door.
+  annotations:
+    cert-manager.io/cluster-issuer: letsencrypt-cluster
+spec:
+  ingressClassName: traefik
+  tls:
+    - hosts:
+        - trmnl-device.renner.uno
+      secretName: trmnl-device-tls
+  rules:
+    - host: trmnl-device.renner.uno
+      http:
+        paths:
+          - path: /
+            pathType: Prefix
+            backend:
+              service:
+                name: terminus
+                port:
+                  number: 80

kubernetes/apps/trmnl/device-service.yaml

@@ -1,15 +1,24 @@
-# Device-facing endpoint. Cleartext HTTP, deliberately.
+# Cleartext fallback for the device, reachable by address only.
 #
-# The TRMNL firmware initiates every request and cannot be handed the
+# This used to be THE device endpoint, on the premise that the firmware
-# internal CA, so terminating TLS here would simply break polling. Scope of
+# "cannot be handed the internal CA". The premise was wrong: nothing here
-# the exposure: this Service is LAN-only (no public DNS label, no Cloudflare
+# hands out an internal CA for these names — letsencrypt-cluster solves
-# record), it carries no admin session — the device authenticates with its
+# DNS-01 against the renner.uno Cloudflare zone and issues publicly-trusted
-# MAC in the `ID` header plus a per-device api_key — and the Terminus admin
+# certificates for LAN-only hosts, which is why trmnl.renner.uno has always
-# UI stays on the TLS route at trmnl.renner.uno.
+# served an issuer CN=YR2 certificate. The device speaks HTTPS via
+# device-ingress.yaml, which now owns the trmnl-device.renner.uno name.
+#
+# Kept, without a hostname, because it is the one path to Terminus that
+# depends on neither Traefik nor certificate renewal: http://10.2.99.89
+# still serves /api/setup and /api/display. If TLS is ever what breaks the
+# panel, the recovery is to type that address into the captive portal.
+#
+# Scope of the exposure is unchanged: LAN-only (no public DNS label, no
+# Cloudflare record), no admin session — the device authenticates with its
+# MAC in the `ID` header plus a per-device api_key.
 #
 # Same shape as home-assistant-bgp: a dedicated address on the Cilium BGP
-# pool rather than a TLS-less Ingress, which would be a new pattern for this
+# pool.
-# repo. The device is provisioned with the HOSTNAME, not the address.
 #
 # The address is requested explicitly, matching every other LB service here.
 # Left to allocate freely, Cilium IPAM handed out the first free address in
@@ -30,8 +39,10 @@ metadata:
   labels:
     app.kubernetes.io/name: terminus
     lb-pool: bgp
+  # No external-dns hostname: device-ingress.yaml claims that name. Two
+  # sources claiming trmnl-device.renner.uno would flap the record between
+  # the Traefik VIP and this address (external-dns runs --policy=sync).
   annotations:
-    external-dns.alpha.kubernetes.io/hostname: trmnl-device.renner.uno
     lbipam.cilium.io/ips: "10.2.99.89,fd99::89"
 spec:
   type: LoadBalancer

kubernetes/apps/trmnl/kustomization.yaml

@@ -6,6 +6,9 @@ resources:
   - valkey.yaml
   - terminus.yaml
   - ingress.yaml
+  # TLS device endpoint (owns trmnl-device.renner.uno) plus the nameless
+  # cleartext LoadBalancer it falls back to.
+  - device-ingress.yaml
   - device-service.yaml
   # Headless HA screenshotter. Lives in this namespace because Terminus
   # FETCHES rendered screens back from it (uri delivery mode), so the

kubernetes/apps/trmnl/terminus.yaml

@@ -7,11 +7,17 @@ data:
   TZ: "Europe/Berlin"
   HANAMI_PORT: "2345"
   # What the device is told to fetch from. Terminus bakes this into the
-  # absolute `image_url` it hands back on /api/display, so it MUST be the
+  # absolute `image_url` it hands back on /api/display, so it has to be a
-  # cleartext LAN name, not trmnl.renner.uno — the firmware speaks plain
+  # name the DEVICE can resolve and fetch — and it has to carry the same
-  # HTTP and would reject the internal CA. No trailing slash: the same
+  # scheme the device polls with, or every screen fetch is a second,
-  # string is typed into the captive portal at provisioning time.
+  # cleartext connection. No trailing slash: the same string is typed into
-  API_URI: "http://trmnl-device.renner.uno"
+  # the captive portal at provisioning time.
+  #
+  # https since device-ingress.yaml took over trmnl-device.renner.uno. The
+  # earlier value was http on the theory that the firmware would reject an
+  # internal CA; there is no internal CA here — letsencrypt-cluster issues
+  # publicly-trusted certs for LAN-only names via DNS-01.
+  API_URI: "https://trmnl-device.renner.uno"
   KEYVALUE_URL: "redis://terminus-valkey:6379"
   # Rack::Attack rate-limit bypass. Beyond upstream's RFC1918 defaults this
   # adds fc00::/7, which covers the pod CIDR (fd10:244::/48), the Cilium LB