feat(k8s): publish the portals through the labs Caddy (refs #177)

Adds a `keycloakUrl` chart value: when set, it replaces host + Keycloak's
NodePort as the pinned issuer and the portals' OIDC authority, so the stack
works behind the existing *.labs.respellion.tech Caddy over HTTPS. Empty keeps
today's behaviour. The deploy workflow passes the KEYCLOAK_URL repo variable.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

infra/helm/big-reference/templates/_helpers.tpl

@@ -135,6 +135,14 @@ cluster-internal hosts ({{ .Release.Namespace }}) and the node address
 {{- end }}
 {{- end -}}
 
+{{/*
+The origin a browser reaches Keycloak on: the issuer Keycloak pins and the
+authority the portals use, from one place so they cannot drift (ADR-0010).
+*/}}
+{{- define "big.keycloakUrl" -}}
+{{- .Values.keycloakUrl | default (printf "http://%s:%v" .Values.host (index .Values.nodePorts "keycloak")) -}}
+{{- end -}}
+
 {{- define "big.labels" -}}
 app.kubernetes.io/name: {{ .name }}
 app.kubernetes.io/instance: {{ .root.Release.Name }}

infra/helm/big-reference/templates/config.yaml

@@ -40,5 +40,5 @@ metadata:
 {{- include "big.labels" (dict "root" $ "name" (printf "portal-config-%s" $realm)) | nindent 4 }}
 data:
   config.json: |
-    { "authority": "{{ printf "http://%s:%v" $.Values.host (index $.Values.nodePorts "keycloak") }}/realms/{{ $realm }}" }
+    { "authority": "{{ include "big.keycloakUrl" $ }}/realms/{{ $realm }}" }
 {{- end }}

infra/helm/big-reference/templates/deployments.yaml

@@ -28,7 +28,7 @@ spec:
       {{- range $w.files }}
       {{- if hasPrefix "portal-config-" .configMap }}
       annotations:
-        checksum/portal-config: {{ printf "%s|%v" $.Values.host (index $.Values.nodePorts "keycloak") | sha256sum }}
+        checksum/portal-config: {{ include "big.keycloakUrl" $ | sha256sum }}
       {{- end }}
       {{- end }}
       labels:

infra/helm/big-reference/values.yaml

@@ -25,6 +25,11 @@
 # string, so browser tokens and the BFF's discovered issuer agree.
 host: 192.168.122.100
 
+# Set when a TLS proxy outside the cluster publishes Keycloak: the full origin, no
+# trailing slash. It replaces `host` + Keycloak's NodePort as the issuer and the
+# portals' authority (runbook, "Publishing through the labs Caddy").
+keycloakUrl: ""
+
 # Set when pulling from a private registry (e.g. the Gitea Container Registry).
 imagePullSecrets: []
 
@@ -268,7 +273,7 @@ workloads:
       # Pin the issuer to the address the browser uses, and let backchannel calls
       # keep using keycloak:8080 — the BFF discovers metadata in-cluster and gets
       # this issuer back, which is what browser tokens carry (infra/host-browser.yml).
-      KC_HOSTNAME: "http://{{ .Values.host }}:{{ index .Values.nodePorts \"keycloak\" }}"
+      KC_HOSTNAME: '{{ include "big.keycloakUrl" . }}'
       KC_HOSTNAME_BACKCHANNEL_DYNAMIC: "true"
     ports: [{ name: http, port: 8080 }]
     # TCP, not /health/ready on the management port: nothing here gates on realm