xds: introduce generic xds clients xDS and LRS Client API signatures

xds/internal/clients/config.go

@@ -16,11 +16,10 @@
  *
  */
 
-// Package clients provides implementations of the xDS and LRS clients,
-// enabling applications to communicate with xDS management servers and report
-// load.
+// Package clients provides implementations of the clients to interact with
+// xDS and LRS servers.
 //
-// xDS Client
+// # xDS Client
 //
 // The xDS client allows applications to:
 //   - Create client instances with in-memory configurations.
@@ -41,100 +40,30 @@
 //
 // NOTICE: This package is EXPERIMENTAL and may be changed or removed
 // in a later release.
-//
-// See [README](https://github.com/grpc/grpc-go/tree/master/xds/clients/README.md).
 package clients
 
-import (
-	"fmt"
-	"slices"
-	"strings"
-
-	"google.golang.org/protobuf/proto"
-	"google.golang.org/protobuf/types/known/structpb"
-
-	v3corepb "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
-)
-
-// ServerConfig holds settings for connecting to an xDS management server.
-type ServerConfig struct {
-	// ServerURI is the target URI of the xDS management server.
+// ServerIdentifier holds identifying information for connecting to an xDS
+// management or LRS server.
+type ServerIdentifier struct {
+	// ServerURI is the target URI of the server.
 	ServerURI string
 
-	// IgnoreResourceDeletion is a server feature which if set to true,
-	// indicates that resource deletion errors can be ignored and cached
-	// resource data can be used.
-	//
-	// This will be removed in the future once we implement gRFC A88
-	// and two new fields FailOnDataErrors and
-	// ResourceTimerIsTransientError will be introduced.
-	IgnoreResourceDeletion bool
-
 	// Extensions can be populated with arbitrary data to be passed to the
-	// [TransportBuilder] and/or xDS Client's ResourceType implementations.
+	// TransportBuilder and/or xDS Client's ResourceType implementations.
 	// This field can be used to provide additional configuration or context
 	// specific to the user's needs.
 	//
 	// The xDS and LRS clients do not interpret the contents of this field.
-	// It is the responsibility of the user's custom [TransportBuilder] and/or
+	// It is the responsibility of the user's custom TransportBuilder and/or
 	// ResourceType implementations to handle and interpret these extensions.
 	//
-	// For example, a custom [TransportBuilder] might use this field to
+	// For example, a custom TransportBuilder might use this field to
 	// configure a specific security credentials.
-	//
-	// Note: For custom types used in Extensions, ensure an Equal(any) bool
-	// method is implemented for equality checks on ServerConfig.
 	Extensions any
 }
 
-// equal returns true if sc and other are considered equal.
-func (sc *ServerConfig) equal(other *ServerConfig) bool {
-	switch {
-	case sc == nil && other == nil:
-		return true
-	case (sc != nil) != (other != nil):
-		return false
-	case sc.ServerURI != other.ServerURI:
-		return false
-	case sc.IgnoreResourceDeletion != other.IgnoreResourceDeletion:
-		return false
-	}
-	if sc.Extensions == nil && other.Extensions == nil {
-		return true
-	}
-	if ex, ok := sc.Extensions.(interface{ Equal(any) bool }); ok && ex.Equal(other.Extensions) {
-		return true
-	}
-	return false
-}
-
-// String returns a string representation of the [ServerConfig].
-//
-// WARNING: This method is primarily intended for logging and testing
-// purposes. The output returned by this method is not guaranteed to be stable
-// and may change at any time. Do not rely on it for production use.
-func (sc *ServerConfig) String() string {
-	return strings.Join([]string{sc.ServerURI, fmt.Sprintf("%v", sc.IgnoreResourceDeletion)}, "-")
-}
-
-// Authority contains configuration for an xDS control plane authority.
-type Authority struct {
-	// XDSServers contains the list of server configurations for this authority.
-	XDSServers []ServerConfig
-
-	// Extensions can be populated with arbitrary data to be passed to the xDS
-	// Client's user specific implementations. This field can be used to
-	// provide additional configuration or context specific to the user's
-	// needs.
-	//
-	// The xDS and LRS clients do not interpret the contents of this field. It
-	// is the responsibility of the user's implementations to handle and
-	// interpret these extensions.
-	Extensions any
-}
-
-// Node represents the identity of the xDS client, allowing
-// management servers to identify the source of xDS requests.
+// Node represents the identity of the xDS client, allowing xDS and LRS servers
+// to identify the source of xDS requests.
 type Node struct {
 	// ID is a string identifier of the application.
 	ID string
@@ -150,40 +79,6 @@ type Node struct {
 	UserAgentName string
 	// UserAgentVersion is the user agent version of application.
 	UserAgentVersion string
-	// ClientFeatures is a list of xDS features supported by this client.
-	// These features are set within the xDS client, but may be overridden only
-	// for testing purposes.
-	clientFeatures []string
-}
-
-// toProto converts an instance of [Node] to its protobuf representation.
-func (n Node) toProto() *v3corepb.Node {
-	return &v3corepb.Node{
-		Id:      n.ID,
-		Cluster: n.Cluster,
-		Locality: func() *v3corepb.Locality {
-			if n.Locality.isEmpty() {
-				return nil
-			}
-			return &v3corepb.Locality{
-				Region:  n.Locality.Region,
-				Zone:    n.Locality.Zone,
-				SubZone: n.Locality.SubZone,
-			}
-		}(),
-		Metadata: func() *structpb.Struct {
-			if n.Metadata == nil {
-				return nil
-			}
-			if md, ok := n.Metadata.(*structpb.Struct); ok {
-				return proto.Clone(md).(*structpb.Struct)
-			}
-			return nil
-		}(),
-		UserAgentName:        n.UserAgentName,
-		UserAgentVersionType: &v3corepb.Node_UserAgentVersion{UserAgentVersion: n.UserAgentVersion},
-		ClientFeatures:       slices.Clone(n.clientFeatures),
-	}
 }
 
 // Locality represents the location of the xDS client application.
@@ -195,13 +90,3 @@ type Locality struct {
 	// SubZone is the further subdivision within a zone.
 	SubZone string
 }
-
-// isEmpty reports whether l is considered empty.
-func (l Locality) isEmpty() bool {
-	return l.equal(Locality{})
-}
-
-// equal returns true if l and other are considered equal.
-func (l Locality) equal(other Locality) bool {
-	return l.Region == other.Region && l.Zone == other.Zone && l.SubZone == other.SubZone
-}