feat: support endpoint override policy based routing

api/v1alpha1/loadbalancer_types.go

@@ -29,6 +29,14 @@ type LoadBalancer struct {
 	// +optional
 	ConsistentHash *ConsistentHash `json:"consistentHash,omitempty"`
 
+	// EndpointOverride defines the configuration for endpoint override.
+	// When specified, the load balancer will attempt to route requests to endpoints
+	// based on the override information extracted from request headers or metadata.
+	//  If the override endpoints are not available, the configured load balancer policy will be used as fallback.
+	//
+	// +optional
+	EndpointOverride *EndpointOverride `json:"endpointOverride,omitempty"`
+
 	// SlowStart defines the configuration related to the slow start load balancer policy.
 	// If set, during slow start window, traffic sent to the newly added hosts will gradually increase.
 	// Currently this is only supported for RoundRobin and LeastRequest load balancers
@@ -178,3 +186,26 @@ type ForceLocalZone struct {
 	// +notImplementedHide
 	MinEndpointsInZoneThreshold *uint32 `json:"minEndpointsInZoneThreshold,omitempty"`
 }
+
+// EndpointOverride defines the configuration for endpoint override.
+// This allows endpoint picking to be implemented based on request headers or metadata.
+// It extracts selected override endpoints from the specified sources (request headers, metadata, etc.).
+// If no valid endpoint in the override list, then the configured load balancing policy is used as fallback.
+type EndpointOverride struct {
+	// ExtractFrom defines the sources to extract endpoint override information from.
+	//
+	// +kubebuilder:validation:MinItems=1
+	// +kubebuilder:validation:MaxItems=10
+	ExtractFrom []EndpointOverrideExtractFrom `json:"extractFrom"`
+}
+
+// EndpointOverrideExtractFrom defines a source to extract endpoint override information from.
+type EndpointOverrideExtractFrom struct {
+	// Header defines the header to get the override endpoint addresses.
+	// The header value must specify at least one endpoint in `IP:Port` format or multiple endpoints in `IP:Port,IP:Port,...` format.
+	// For example `10.0.0.5:8080` or `[2600:4040:5204::1574:24ae]:80`.
+	// The IPv6 address is enclosed in square brackets.
+	//
+	// +optional
+	Header *string `json:"header,omitempty"`
+}

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

@@ -668,6 +668,34 @@ spec:
                     - message: If consistent hash type is cookie, the cookie field
                         must be set.
                       rule: 'self.type == ''Cookie'' ? has(self.cookie) : !has(self.cookie)'
+                  endpointOverride:
+                    description: |-
+                      EndpointOverride defines the configuration for endpoint override.
+                      When specified, the load balancer will attempt to route requests to endpoints
+                      based on the override information extracted from request headers or metadata.
+                       If the override endpoints are not available, the configured load balancer policy will be used as fallback.
+                    properties:
+                      extractFrom:
+                        description: ExtractFrom defines the sources to extract endpoint
+                          override information from.
+                        items:
+                          description: EndpointOverrideExtractFrom defines a source
+                            to extract endpoint override information from.
+                          properties:
+                            header:
+                              description: |-
+                                Header defines the header to get the override endpoint addresses.
+                                The header value must specify at least one endpoint in `IP:Port` format or multiple endpoints in `IP:Port,IP:Port,...` format.
+                                For example `10.0.0.5:8080` or `[2600:4040:5204::1574:24ae]:80`.
+                                The IPv6 address is enclosed in square brackets.
+                              type: string
+                          type: object
+                        maxItems: 10
+                        minItems: 1
+                        type: array
+                    required:
+                    - extractFrom
+                    type: object
                   slowStart:
                     description: |-
                       SlowStart defines the configuration related to the slow start load balancer policy.

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

@@ -746,6 +746,35 @@ spec:
                                   field must be set.
                                 rule: 'self.type == ''Cookie'' ? has(self.cookie)
                                   : !has(self.cookie)'
+                            endpointOverride:
+                              description: |-
+                                EndpointOverride defines the configuration for endpoint override.
+                                When specified, the load balancer will attempt to route requests to endpoints
+                                based on the override information extracted from request headers or metadata.
+                                 If the override endpoints are not available, the configured load balancer policy will be used as fallback.
+                              properties:
+                                extractFrom:
+                                  description: ExtractFrom defines the sources to
+                                    extract endpoint override information from.
+                                  items:
+                                    description: EndpointOverrideExtractFrom defines
+                                      a source to extract endpoint override information
+                                      from.
+                                    properties:
+                                      header:
+                                        description: |-
+                                          Header defines the header to get the override endpoint addresses.
+                                          The header value must specify at least one endpoint in `IP:Port` format or multiple endpoints in `IP:Port,IP:Port,...` format.
+                                          For example `10.0.0.5:8080` or `[2600:4040:5204::1574:24ae]:80`.
+                                          The IPv6 address is enclosed in square brackets.
+                                        type: string
+                                    type: object
+                                  maxItems: 10
+                                  minItems: 1
+                                  type: array
+                              required:
+                              - extractFrom
+                              type: object
                             slowStart:
                               description: |-
                                 SlowStart defines the configuration related to the slow start load balancer policy.