longhorn: log in through authentik on the Gateway

Longhorn has no users of its own; nginx guarded it with basic auth using apr1 hashes, which Envoy Gateway does not support. An Envoy Gateway SecurityPolicy now sends visitors through an authentik OIDC application that only admins may use. The client secret lives in Vault at kv/longhorn-oidc and reaches both authentik and Envoy through External Secrets.

gateway/gateway.yaml

@@ -212,3 +212,17 @@ spec:
         selector:
           matchLabels:
             kubernetes.io/metadata.name: argocd
+  - name: https-longhorn
+    protocol: HTTPS
+    port: 443
+    hostname: longhorn.rubenhensen.nl
+    tls:
+      certificateRefs:
+      - name: letsencrypt-prod
+        namespace: longhorn-system
+    allowedRoutes:
+      namespaces:
+        from: Selector
+        selector:
+          matchLabels:
+            kubernetes.io/metadata.name: longhorn-system