feat: support overriding ext_auth path

Signed-off-by: Rudrakh Panigrahi <rudrakh97@gmail.com>

Author: rudrakhp

api/v1alpha1/ext_auth_types.go

@@ -148,6 +148,7 @@ type GRPCExtAuthService struct {
 // +kubebuilder:validation:XValidation:message="backendRef or backendRefs needs to be set",rule="has(self.backendRef) || self.backendRefs.size() > 0"
 // +kubebuilder:validation:XValidation:message="BackendRefs only supports Service, ServiceImport, and Backend kind.",rule="has(self.backendRefs) ? self.backendRefs.all(f, f.kind == 'Service' || f.kind == 'ServiceImport' || f.kind == 'Backend') : true"
 // +kubebuilder:validation:XValidation:message="BackendRefs only supports Core, multicluster.x-k8s.io, and gateway.envoyproxy.io groups.",rule="has(self.backendRefs) ? (self.backendRefs.all(f, f.group == \"\" || f.group == 'multicluster.x-k8s.io' || f.group == 'gateway.envoyproxy.io')) : true"
+// +kubebuilder:validation:XValidation:message="only one of path or pathOverride can be specified",rule="!(has(self.path) && has(self.pathOverride))"
 type HTTPExtAuthService struct {
 	// Only Service kind is supported for now.
 	BackendCluster `json:",inline"`
@@ -160,9 +161,19 @@ type HTTPExtAuthService struct {
 	// For example, if the original request path is "/hello", and the path specified here is "/auth",
 	// then the path of the authorization request will be "/auth/hello". If the path is not specified,
 	// the path of the authorization request will be "/hello".
+	// Only one of Path or PathOverride can be set.
 	// +optional
 	Path *string `json:"path,omitempty"`
 
+	// PathOverride replaces the original request path in the authorization request.
+	// If set, the path will be overridden to this value during authorization.
+	// For example, if the original request path is "/hello", and PathOverride is set to "/auth",
+	// then the path of the authorization request will be "/auth".
+	// Only one of Path or PathOverride can be set.
+	//
+	// +optional
+	PathOverride *string `json:"pathOverride,omitempty"`
+
 	// HeadersToBackend are the authorization response headers that will be added
 	// to the original client request before sending it to the backend server.
 	// Note that coexisting headers will be overridden.

api/v1alpha1/zz_generated.deepcopy.go

@@ -3423,6 +3423,15 @@ spec:
                           For example, if the original request path is "/hello", and the path specified here is "/auth",
                           then the path of the authorization request will be "/auth/hello". If the path is not specified,
                           the path of the authorization request will be "/hello".
+                          Only one of Path or PathOverride can be set.
+                        type: string
+                      pathOverride:
+                        description: |-
+                          PathOverride replaces the original request path in the authorization request.
+                          If set, the path will be overridden to this value during authorization.
+                          For example, if the original request path is "/hello", and PathOverride is set to "/auth",
+                          then the path of the authorization request will be "/auth".
+                          Only one of Path or PathOverride can be set.
                         type: string
                     type: object
                     x-kubernetes-validations:
@@ -3438,6 +3447,8 @@ spec:
                       rule: 'has(self.backendRefs) ? (self.backendRefs.all(f, f.group
                         == "" || f.group == ''multicluster.x-k8s.io'' || f.group ==
                         ''gateway.envoyproxy.io'')) : true'
+                    - message: only one of path or pathOverride can be specified
+                      rule: '!(has(self.path) && has(self.pathOverride))'
                   recomputeRoute:
                     description: |-
                       RecomputeRoute clears the route cache and recalculates the routing decision.

charts/gateway-crds-helm/templates/generated/gateway.envoyproxy.io_securitypolicies.yaml

@@ -3422,6 +3422,15 @@ spec:
                           For example, if the original request path is "/hello", and the path specified here is "/auth",
                           then the path of the authorization request will be "/auth/hello". If the path is not specified,
                           the path of the authorization request will be "/hello".
+                          Only one of Path or PathOverride can be set.
+                        type: string
+                      pathOverride:
+                        description: |-
+                          PathOverride replaces the original request path in the authorization request.
+                          If set, the path will be overridden to this value during authorization.
+                          For example, if the original request path is "/hello", and PathOverride is set to "/auth",
+                          then the path of the authorization request will be "/auth".
+                          Only one of Path or PathOverride can be set.
                         type: string
                     type: object
                     x-kubernetes-validations:
@@ -3437,6 +3446,8 @@ spec:
                       rule: 'has(self.backendRefs) ? (self.backendRefs.all(f, f.group
                         == "" || f.group == ''multicluster.x-k8s.io'' || f.group ==
                         ''gateway.envoyproxy.io'')) : true'
+                    - message: only one of path or pathOverride can be specified
+                      rule: '!(has(self.path) && has(self.pathOverride))'
                   recomputeRoute:
                     description: |-
                       RecomputeRoute clears the route cache and recalculates the routing decision.

charts/gateway-helm/charts/crds/crds/generated/gateway.envoyproxy.io_securitypolicies.yaml

@@ -178,6 +178,7 @@ func authCheckerHandler(w http.ResponseWriter, req *http.Request) {
 	if len(extracted) == 2 && extracted[0] == "Bearer" {
 		if user, ok := testUsers[extracted[1]]; ok {
 			w.Header().Add("x-current-user", user) // this should be set before call WriteHeader
+			w.Header().Add("x-ext-auth-req-path", req.URL.Path)
 			w.WriteHeader(http.StatusOK)
 			return
 		}

examples/envoy-ext-auth/main.go

@@ -2204,6 +2204,7 @@ func (t *Translator) buildExtAuth(
 			Destination:      *rd,
 			Authority:        authority,
 			Path:             ptr.Deref(http.Path, ""),
+			PathOverride:     ptr.Deref(http.PathOverride, ""),
 			HeadersToBackend: http.HeadersToBackend,
 		}
 	} else {

internal/gatewayapi/securitypolicy.go

@@ -0,0 +1,126 @@
+gateways:
+  - apiVersion: gateway.networking.k8s.io/v1
+    kind: Gateway
+    metadata:
+      namespace: default
+      name: gateway-1
+    spec:
+      gatewayClassName: envoy-gateway-class
+      listeners:
+        - name: http
+          protocol: HTTP
+          port: 80
+          allowedRoutes:
+            namespaces:
+              from: All
+httpRoutes:
+  - apiVersion: gateway.networking.k8s.io/v1
+    kind: HTTPRoute
+    metadata:
+      namespace: default
+      name: httproute-1
+    spec:
+      hostnames:
+        - www.foo.com
+      parentRefs:
+        - namespace: default
+          name: gateway-1
+          sectionName: http
+      rules:
+        - matches:
+            - path:
+                value: /foo
+          backendRefs:
+            - name: service-1
+              port: 8080
+services:
+  - apiVersion: v1
+    kind: Service
+    metadata:
+      namespace: envoy-gateway
+      name: http-backend
+    spec:
+      ports:
+        - port: 80
+          name: http
+          protocol: TCP
+  - apiVersion: v1
+    kind: Service
+    metadata:
+      namespace: default
+      name: service-1
+    spec:
+      ports:
+        - port: 8080
+          name: http
+          protocol: TCP
+endpointSlices:
+  - apiVersion: discovery.k8s.io/v1
+    kind: EndpointSlice
+    metadata:
+      name: endpointslice-http-backend
+      namespace: envoy-gateway
+      labels:
+        kubernetes.io/service-name: http-backend
+    addressType: IPv4
+    ports:
+      - name: http
+        protocol: TCP
+        port: 80
+    endpoints:
+      - addresses:
+          - 7.7.7.7
+        conditions:
+          ready: true
+  - apiVersion: discovery.k8s.io/v1
+    kind: EndpointSlice
+    metadata:
+      name: endpointslice-service-1
+      namespace: default
+      labels:
+        kubernetes.io/service-name: service-1
+    addressType: IPv4
+    ports:
+      - name: http
+        protocol: TCP
+        port: 8080
+    endpoints:
+      - addresses:
+          - 8.8.8.8
+        conditions:
+          ready: true
+referenceGrants:
+  - apiVersion: gateway.networking.k8s.io/v1alpha2
+    kind: ReferenceGrant
+    metadata:
+      namespace: envoy-gateway
+      name: referencegrant-1
+    spec:
+      from:
+        - group: gateway.envoyproxy.io
+          kind: SecurityPolicy
+          namespace: default
+      to:
+        - group: ""
+          kind: Service
+securityPolicies:
+  - apiVersion: gateway.envoyproxy.io/v1alpha1
+    kind: SecurityPolicy
+    metadata:
+      namespace: default
+      name: policy-for-gateway-1
+    spec:
+      targetRef:
+        group: gateway.networking.k8s.io
+        kind: Gateway
+        name: gateway-1
+      extAuth:
+        failOpen: false
+        http:
+          backendRefs:
+            - Name: http-backend
+              Namespace: envoy-gateway
+              Port: 80
+          pathOverride: /check
+          headersToBackend:
+            - x-user