sdk changes to retrieve upstrem

sdk/core/policy/v1alpha2/action.go

@@ -43,6 +43,7 @@ type UpstreamRequestHeaderModifications struct {
 	// These are valid at the header phase because routing decisions do not require
 	// the request body to be available.
 	UpstreamName            *string             // route to a named upstream definition (nil = no change)
+	UpstreamSlot            *UpstreamSlot       // route to the API's main or sandbox upstream slot instead of the slot implied by the current vhost (nil = no change); requesting a slot the API doesn't have configured is a no-op (logged, not an error)
 	Path                    *string             // rewrite the request path (nil = no change)
 	Host                    *string             // rewrite the :authority header (nil = no change)
 	Method                  *string             // rewrite the request method (nil = no change)
@@ -113,6 +114,7 @@ type UpstreamRequestModifications struct {
 
 	// Routing mutations — applied before the request is forwarded to upstream.
 	UpstreamName            *string             // route to a named upstream definition (nil = no change)
+	UpstreamSlot            *UpstreamSlot       // route to the API's main or sandbox upstream slot instead of the slot implied by the current vhost (nil = no change); requesting a slot the API doesn't have configured is a no-op (logged, not an error)
 	Path                    *string             // rewrite the request path (nil = no change)
 	Host                    *string             // rewrite the :authority header (nil = no change)
 	Method                  *string             // rewrite the request method (nil = no change)

sdk/core/policy/v1alpha2/context.go

@@ -1,5 +1,7 @@
 package policyv1alpha2
 
+import policyenginev1 "github.com/wso2/api-platform/sdk/core/policyengine"
+
 // Body represents HTTP request or response body data
 type Body struct {
 	// Content is the body payload (may be nil)
@@ -90,6 +92,13 @@ type RequestContext struct {
 	Authority string
 	Scheme    string
 	Vhost     string
+
+	// UpstreamInfo identifies the route's resolved upstream target (cluster name, URL,
+	// base path) for this request. Nil if no upstream has been resolved for the route.
+	// Authority/Scheme above reflect the inbound client-facing request and must not be
+	// used to address the actual upstream (e.g. for request signing) — use
+	// UpstreamInfo.URL instead.
+	UpstreamInfo *policyenginev1.UpstreamInfo
 }
 
 // ─── Response-phase contexts ─────────────────────────────────────────────────

sdk/core/policy/v1alpha2/types.go

@@ -13,6 +13,14 @@ const (
 	APIKindWebSubApi   APIKind = "WebSubApi"
 )
 
+// UpstreamSlot identifies one of an API's built-in upstream slots.
+type UpstreamSlot string
+
+const (
+	UpstreamSlotMain    UpstreamSlot = "main"
+	UpstreamSlotSandbox UpstreamSlot = "sandbox"
+)
+
 // ParameterType defines the type of a policy parameter
 type ParameterType string
 

sdk/core/policyengine/upstream.go

@@ -0,0 +1,39 @@
+package policyengine
+
+// UpstreamInfo identifies the resolved upstream target for one of an API's
+// upstream slots (main or sandbox) or a named upstream definition: the Envoy
+// cluster name (used for cluster_header dynamic routing) and the raw resolved
+// URL. This is the shared wire shape used on both sides of the xDS route-config
+// channel between gateway-controller and policy-engine.
+type UpstreamInfo struct {
+	ClusterName string `json:"cluster_name" yaml:"cluster_name"`
+	URL         string `json:"url" yaml:"url"`
+	BasePath    string `json:"base_path" yaml:"base_path"`
+}
+
+// ToMap converts UpstreamInfo into a structpb-compatible map for embedding as a
+// nested object in xDS route-config metadata (structpb.Struct only accepts
+// string/bool/number/nil/slice/map values, not arbitrary structs).
+func (u UpstreamInfo) ToMap() map[string]interface{} {
+	return map[string]interface{}{
+		"cluster_name": u.ClusterName,
+		"url":          u.URL,
+		"base_path":    u.BasePath,
+	}
+}
+
+// UpstreamInfoFromMap decodes an UpstreamInfo from the generic map produced when
+// the xDS metadata struct is unmarshalled back to JSON on the consumer side.
+func UpstreamInfoFromMap(m map[string]interface{}) UpstreamInfo {
+	get := func(k string) string {
+		if s, ok := m[k].(string); ok {
+			return s
+		}
+		return ""
+	}
+	return UpstreamInfo{
+		ClusterName: get("cluster_name"),
+		URL:         get("url"),
+		BasePath:    get("base_path"),
+	}
+}

sdk/core/policyengine/upstream_test.go

@@ -0,0 +1,33 @@
+package policyengine
+
+import "testing"
+
+func TestUpstreamInfoRoundTrip(t *testing.T) {
+	info := UpstreamInfo{
+		ClusterName: "cluster_https_backend_example_com",
+		URL:         "https://backend.example.com",
+		BasePath:    "/v1",
+	}
+
+	got := UpstreamInfoFromMap(info.ToMap())
+
+	if got != info {
+		t.Errorf("round trip mismatch: got %+v, want %+v", got, info)
+	}
+}
+
+func TestUpstreamInfoFromMapMissingFields(t *testing.T) {
+	got := UpstreamInfoFromMap(map[string]interface{}{"cluster_name": "c1"})
+	want := UpstreamInfo{ClusterName: "c1"}
+	if got != want {
+		t.Errorf("got %+v, want %+v", got, want)
+	}
+}
+
+func TestUpstreamInfoFromMapWrongType(t *testing.T) {
+	got := UpstreamInfoFromMap(map[string]interface{}{"cluster_name": 42})
+	want := UpstreamInfo{}
+	if got != want {
+		t.Errorf("got %+v, want %+v", got, want)
+	}
+}