feat(comfyui): put ComfyUI behind ZITADEL single sign-on

comfyui.riotpiao.com is served with no authentication at all: anyone who can
resolve the host reaches the UI and its queue. ComfyUI has no OIDC support, so the
front door is oauth2-proxy, and nginx asks it for a decision on every request.

Nothing inside the cluster calls this host, so the whole host is gated rather than
carved into open and closed paths. If a client ever needs direct access, add a skip
rule for its exact paths.

The ZITADEL app is created by the provisioning script, and the client secret,
cookie secret and client id live in a SOPS secret written by ksops.

k8s/apps/comfyui/ingress.yaml

@@ -13,6 +13,11 @@ metadata:
     # WebSocket support for ComfyUI's live preview
     nginx.ingress.kubernetes.io/proxy-http-version: "1.1"
     nginx.ingress.kubernetes.io/upstream-hash-by: "$remote_addr"
+    # Single sign-on. ComfyUI has no auth of its own, so every request is handed to
+    # oauth2-proxy for an allow or deny decision.
+    nginx.ingress.kubernetes.io/auth-url: "http://comfyui-oauth2-proxy.comfyui.svc.cluster.local:4180/oauth2/auth"
+    nginx.ingress.kubernetes.io/auth-signin: "https://comfyui.riotpiao.com/oauth2/start?rd=$scheme://$host$request_uri"
+    nginx.ingress.kubernetes.io/auth-response-headers: "x-auth-request-user,x-auth-request-email"
     nginx.ingress.kubernetes.io/configuration-snippet: |
       proxy_set_header Upgrade $http_upgrade;
       proxy_set_header Connection "upgrade";

k8s/apps/comfyui/kustomization.yaml

@@ -4,4 +4,5 @@ kind: Kustomization
 resources:
   - deployment.yaml
   - service.yaml
+  - oauth2-proxy.yaml
   - ingress.yaml

k8s/apps/comfyui/oauth2-proxy.yaml

@@ -0,0 +1,101 @@
+# ComfyUI has no authentication of its own: comfyui.riotpiao.com is open to anyone
+# who can resolve the host. It also has no OIDC support, so ZITADEL cannot be a
+# login method inside it. oauth2-proxy is the front door instead: nginx asks it for
+# a decision on every request and it answers from a ZITADEL session.
+#
+# No API client calls this host today, so the whole host is gated. If a client ever
+# needs direct access, add a skip rule for the exact paths it uses rather than
+# opening the whole host.
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: comfyui-oauth2-proxy
+  namespace: comfyui
+  labels:
+    app: comfyui-oauth2-proxy
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: comfyui-oauth2-proxy
+  template:
+    metadata:
+      labels:
+        app: comfyui-oauth2-proxy
+    spec:
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 65534
+        seccompProfile: {type: RuntimeDefault}
+      containers:
+        - name: oauth2-proxy
+          image: quay.io/oauth2-proxy/oauth2-proxy:v7.7.1
+          args:
+            - --provider=oidc
+            - --oidc-issuer-url=https://zitadel.riotpiao.com
+            - --email-domain=*
+            - --upstream=static://202
+            - --reverse-proxy=true
+            - --set-xauthrequest=true
+            - --cookie-secure=true
+            - --cookie-expire=12h
+            - --cookie-refresh=1h
+            - --skip-provider-button=true
+            - --redirect-url=https://comfyui.riotpiao.com/oauth2/callback
+            - --http-address=0.0.0.0:4180
+          env:
+            - name: OAUTH2_PROXY_CLIENT_ID
+              valueFrom: {secretKeyRef: {name: comfyui-oauth2-proxy, key: client-id}}
+            - name: OAUTH2_PROXY_CLIENT_SECRET
+              valueFrom: {secretKeyRef: {name: comfyui-oauth2-proxy, key: client-secret}}
+            - name: OAUTH2_PROXY_COOKIE_SECRET
+              valueFrom: {secretKeyRef: {name: comfyui-oauth2-proxy, key: cookie-secret}}
+          ports:
+            - {name: http, containerPort: 4180}
+          readinessProbe:
+            httpGet: {path: /ping, port: http}
+            initialDelaySeconds: 5
+          livenessProbe:
+            httpGet: {path: /ping, port: http}
+            initialDelaySeconds: 15
+          securityContext:
+            allowPrivilegeEscalation: false
+            capabilities: {drop: ["ALL"]}
+          resources:
+            requests: {cpu: 10m, memory: 32Mi}
+            limits: {cpu: 200m, memory: 128Mi}
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: comfyui-oauth2-proxy
+  namespace: comfyui
+  labels:
+    app: comfyui-oauth2-proxy
+spec:
+  type: ClusterIP
+  selector:
+    app: comfyui-oauth2-proxy
+  ports:
+    - {name: http, port: 4180, targetPort: http}
+---
+# The proxy needs its own path. The auth_request annotation on the main ingress would
+# otherwise also guard /oauth2/start, and the login entry point would demand a login.
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: comfyui-oauth2
+  namespace: comfyui
+spec:
+  ingressClassName: nginx
+  rules:
+    - host: comfyui.riotpiao.com
+      http:
+        paths:
+          - path: /oauth2
+            pathType: Prefix
+            backend:
+              service:
+                name: comfyui-oauth2-proxy
+                port:
+                  number: 4180