Put the artifactapi web UI behind Authentik oauth2-proxy (#456)

The artifactapi web UI is open to anyone who can reach the host. Front it with Authentik SSO gated on akP-artifactapi-admin, while leaving the package-manager surfaces (/api/v1, /api/v2, /v2 docker registry, /terraform, /.well-known) untouched — dnf, containerd mirrors, buildah, terraform and CI publish steps cannot do a browser flow.

- Add the oauth2-proxy ConfigMap, Deployment, Service and VMPodScrape.
- Add the oauth-credentials VaultStaticSecret.
- Point the api-route /ui rule at oauth2-proxy and add a /oauth2 rule; the catch-all / rule still goes straight to the api Service on both listeners.

Requires terraform-authentik #34 applied and the Vault kv seed first.

Reviewed-on: #456
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

apps/base/artifactapi/httproute.yaml

@@ -1,4 +1,21 @@
 ---
+# Path split between the authenticated UI and the unauthenticated machine API.
+# Longest matching prefix wins, so the two UI rules take precedence over "/".
+#
+# AUTHENTICATED (oauth2 Service -> oauth2-proxy -> ui Service):
+#   /oauth2   oauth2-proxy sign_in / start / callback / sign_out
+#   /ui       the human-facing SPA
+#
+# NOT AUTHENTICATED (artifactapi Service, unchanged):
+#   /api/v1/{remote,local,virtual}/*   package proxy reads (yum/dnf, pip, ...)
+#   /api/v2/remotes|virtuals|locals/*  management API + the UI's own XHR calls
+#   /api/v2/remotes/{name}/files/*     CI publish uploads (PUT) and downloads
+#   /v2/*                              Docker Registry V2 (containerd, buildah)
+#   /terraform/v1/providers/*          Terraform provider registry
+#   /.well-known/terraform.json        Terraform service discovery
+#   /health, /version, /               probes and the redirect to /ui/
+# Those clients cannot complete a browser OIDC flow, so they must never be
+# routed through oauth2-proxy.
 apiVersion: gateway.networking.k8s.io/v1
 kind: HTTPRoute
 metadata:
@@ -22,7 +39,17 @@ spec:
     - backendRefs:
         - group: ""
           kind: Service
-          name: ui
+          name: oauth2
+          port: 80
+          weight: 1
+      matches:
+        - path:
+            type: PathPrefix
+            value: /oauth2
+    - backendRefs:
+        - group: ""
+          kind: Service
+          name: oauth2
           port: 80
           weight: 1
       matches:

apps/base/artifactapi/kustomization.yaml

@@ -12,6 +12,8 @@ resources:
   - gateway.yaml
   - httproute.yaml
   - namespace.yaml
+  - oauth2-proxy-configmap.yaml
+  - oauth2-proxy-deployment.yaml
   - redis-deployment.yaml
   - services.yaml
   - ui-deployment.yaml

apps/base/artifactapi/oauth2-proxy-configmap.yaml

@@ -0,0 +1,41 @@
+---
+# Non-secret oauth2-proxy configuration (client_id/secret/cookie_secret come
+# from the oauth-credentials Secret).
+#
+# SCOPE: this proxy fronts the artifactapi web UI ONLY. The HTTPRoute sends just
+# /ui and /oauth2 here; every machine surface (/api/v1, /api/v2, /v2 docker
+# registry, /terraform, /.well-known/terraform.json, /health, /version, /) goes
+# straight to the api Service and is NOT authenticated. yum/dnf, containerd
+# registry mirrors, docker/buildah, terraform init and Woodpecker publish steps
+# cannot complete a browser OIDC flow, so they must never reach this container.
+# Its only upstream is the ui Service -- there is deliberately no api upstream.
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: artifactapi-oauth2-env
+  namespace: artifactapi
+data:
+  OAUTH2_PROXY_HTTP_ADDRESS: "0.0.0.0:4180"
+  OAUTH2_PROXY_METRICS_ADDRESS: "0.0.0.0:44180"
+  OAUTH2_PROXY_PROVIDER: "oidc"
+  # Publicly-trusted Authentik host: the authorize step is a browser redirect,
+  # so the issuer must present a cert every user's browser already trusts (the
+  # k8s host serves an internal-CA cert). Slug from terraform-authentik.
+  OAUTH2_PROXY_OIDC_ISSUER_URL: "https://identity.unkin.net/application/o/artifactapi/"
+  OAUTH2_PROXY_REDIRECT_URL: "https://artifactapi.k8s.syd1.au.unkin.net/oauth2/callback"
+  OAUTH2_PROXY_UPSTREAMS: "http://ui.artifactapi.svc.cluster.local:80/"
+  OAUTH2_PROXY_SCOPE: "openid email profile ak_groups"
+  # Populate session.Groups from the Authentik hierarchical ak_groups claim.
+  OAUTH2_PROXY_OIDC_GROUPS_CLAIM: "ak_groups"
+  OAUTH2_PROXY_ALLOWED_GROUPS: "akP-artifactapi-admin"
+  OAUTH2_PROXY_PASS_USER_HEADERS: "true"
+  OAUTH2_PROXY_EMAIL_DOMAINS: "*"
+  # Authentik hardcodes email_verified=false in the id_token; authorization is
+  # enforced via ak_groups, so accepting the unverified email is safe.
+  OAUTH2_PROXY_INSECURE_OIDC_ALLOW_UNVERIFIED_EMAIL: "true"
+  OAUTH2_PROXY_COOKIE_SECURE: "true"
+  OAUTH2_PROXY_COOKIE_DOMAINS: "artifactapi.k8s.syd1.au.unkin.net"
+  OAUTH2_PROXY_WHITELIST_DOMAINS: "artifactapi.k8s.syd1.au.unkin.net"
+  OAUTH2_PROXY_REVERSE_PROXY: "true"
+  OAUTH2_PROXY_CODE_CHALLENGE_METHOD: "S256"
+  OAUTH2_PROXY_SKIP_PROVIDER_BUTTON: "true"

apps/base/artifactapi/oauth2-proxy-deployment.yaml

@@ -0,0 +1,93 @@
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: oauth2
+  namespace: artifactapi
+  annotations:
+    configmap.reloader.stakater.com/auto: "true"
+    secret.reloader.stakater.com/reload: "oauth-credentials"
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app: oauth2
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+    type: RollingUpdate
+  template:
+    metadata:
+      labels:
+        app: oauth2
+    spec:
+      serviceAccountName: default
+      automountServiceAccountToken: false
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 65532
+        runAsGroup: 65532
+        fsGroup: 65532
+        seccompProfile:
+          type: RuntimeDefault
+      containers:
+        - name: oauth2-proxy
+          image: quay.io/oauth2-proxy/oauth2-proxy:v7.15.3
+          imagePullPolicy: IfNotPresent
+          ports:
+            - containerPort: 4180
+              name: http
+              protocol: TCP
+            - containerPort: 44180
+              name: metrics
+              protocol: TCP
+          envFrom:
+            - configMapRef:
+                name: artifactapi-oauth2-env
+                optional: false
+          env:
+            - name: OAUTH2_PROXY_CLIENT_ID
+              valueFrom:
+                secretKeyRef:
+                  name: oauth-credentials
+                  key: client_id
+            - name: OAUTH2_PROXY_CLIENT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: oauth-credentials
+                  key: client_secret
+            - name: OAUTH2_PROXY_COOKIE_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: oauth-credentials
+                  key: cookie_secret
+          livenessProbe:
+            httpGet:
+              path: /ping
+              port: http
+            initialDelaySeconds: 10
+            periodSeconds: 30
+            timeoutSeconds: 5
+            failureThreshold: 3
+          readinessProbe:
+            httpGet:
+              path: /ready
+              port: http
+            initialDelaySeconds: 5
+            periodSeconds: 10
+            timeoutSeconds: 5
+            failureThreshold: 3
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop:
+                - ALL
+          resources:
+            requests:
+              cpu: 50m
+              memory: 64Mi
+            limits:
+              cpu: 500m
+              memory: 256Mi
+      restartPolicy: Always

apps/base/artifactapi/services.yaml

@@ -16,6 +16,26 @@ spec:
   sessionAffinity: None
   type: ClusterIP
 ---
+# Authenticated front door for the web UI only: api-route sends /ui and /oauth2
+# here, oauth2-proxy authenticates and forwards to the ui Service. Every other
+# path reaches the api Service above directly and stays unauthenticated.
+apiVersion: v1
+kind: Service
+metadata:
+  name: oauth2
+  namespace: artifactapi
+spec:
+  internalTrafficPolicy: Cluster
+  ports:
+    - name: http
+      port: 80
+      protocol: TCP
+      targetPort: http
+  selector:
+    app: oauth2
+  sessionAffinity: None
+  type: ClusterIP
+---
 apiVersion: v1
 kind: Service
 metadata:

apps/base/artifactapi/vaultstaticsecret.yaml

@@ -32,3 +32,26 @@ spec:
   refreshAfter: 5m
   type: kv-v2
   vaultAuthRef: default
+---
+# Authentik OIDC client for the artifactapi UI front door (client_id,
+# client_secret, cookie_secret). Seeded out of band at
+# kv/kubernetes/namespace/artifactapi/default/oauth-credentials; the default
+# k8s auth role already grants the artifactapi/default ServiceAccount read on
+# kv/data/kubernetes/namespace/{{sa_namespace}}/{{sa_name}}/*, so no
+# terraform-vault change is needed. Consumed by the oauth2 Deployment.
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultStaticSecret
+metadata:
+  name: oauth-credentials
+  namespace: artifactapi
+spec:
+  destination:
+    create: true
+    name: oauth-credentials
+    overwrite: true
+  hmacSecretData: true
+  mount: kv
+  path: kubernetes/namespace/artifactapi/default/oauth-credentials
+  refreshAfter: 5m
+  type: kv-v2
+  vaultAuthRef: default

apps/base/artifactapi/vmpodscrape.yaml

@@ -14,3 +14,17 @@ spec:
   podMetricsEndpoints:
     - port: metrics
       path: /metrics
+---
+# Scrape the UI oauth2-proxy (:44180), which exposes sign-in/authz counters.
+apiVersion: operator.victoriametrics.com/v1beta1
+kind: VMPodScrape
+metadata:
+  name: oauth2
+  namespace: artifactapi
+spec:
+  selector:
+    matchLabels:
+      app: oauth2
+  podMetricsEndpoints:
+    - port: metrics
+      path: /metrics