storage: Use Authelia for Longhorn UI auth

Instead of using a static username/password and HTTP Basic
authentication for the Longhorn UI, we can now use Authelia via the
*nginx* auth subrequest functionality.

storage/longhorn-ingress.yaml

@@ -4,14 +4,12 @@ metadata:
   name: longhorn-ingress
   namespace: longhorn-system
   annotations:
-    # type of authentication
-    nginx.ingress.kubernetes.io/auth-type: basic
-    # prevent the controller from redirecting (308) to HTTPS
-    nginx.ingress.kubernetes.io/ssl-redirect: 'false'
-    # name of the secret that contains the user/password definitions
-    nginx.ingress.kubernetes.io/auth-secret: basic-auth
-    # message to display with an appropriate context why the authentication is required
-    nginx.ingress.kubernetes.io/auth-realm: 'Authentication Required '
+    nginx.ingress.kubernetes.io/auth-method: GET
+    nginx.ingress.kubernetes.io/auth-url: http://authelia.authelia.svc.cluster.local:9091/api/verify
+    nginx.ingress.kubernetes.io/auth-signin: https://auth.pyrocufflink.blue/?rm=$request_method
+    nginx.ingress.kubernetes.io/auth-response-headers: Remote-User,Remote-Name,Remote-Groups,Remote-Email
+    nginx.ingress.kubernetes.io/auth-snippet: |
+      proxy_set_header X-Forwarded-Method $request_method;
     # custom max body size for file uploading like backing image uploading
     nginx.ingress.kubernetes.io/proxy-body-size: 10000m
 spec: