chart: bind the HTTPRoute to a named gateway listener

The route carried no sectionName, so it attached to every listener whose
hostname matched — including the hostname-less plaintext HTTP listener.
On a publicly reachable hostname that means the API accepts bearer tokens
over cleartext.

networking.listener names the listener to bind to. It defaults to empty,
which keeps the previous attach-to-all behaviour.

Also document the Kubernetes install path, which the README omitted.

charts/terdut-server/Chart.yaml

@@ -2,5 +2,5 @@ apiVersion: v2
 name: terdut-server
 description: A Helm chart for Terminal Duty — on-call alert management server
 type: application
-version: 0.2.0
+version: 0.5.0
 appVersion: "latest"

charts/terdut-server/templates/httpproxy.yaml

@@ -9,6 +9,9 @@ spec:
   parentRefs:
   - name: envoy-main
     namespace: envoy-gateway-system
+    {{- with .Values.networking.listener }}
+    sectionName: {{ . | quote }}
+    {{- end }}
   rules:
   - backendRefs:
     - name: {{ include "terdut-server.fullname" . }}

charts/terdut-server/values.yaml

@@ -1,6 +1,10 @@
 networking:
   hostname: "terdut.example.com"
   servicePort: 8080
+  # Gateway listener to bind the HTTPRoute to. Empty attaches to every matching
+  # listener, including plaintext HTTP. Set this to the name of the HTTPS
+  # listener to serve the API over TLS only.
+  listener: ""
 
 image:
   repository: ghcr.io/yeniklas/terdut-server