feat: add new api services (#5619)

* feat: add new services

* improve demos and comments

* remove unused field

* add comment to demo proto calls

* Apply suggestions from code review

Co-authored-by: Silvan <silvan.reusser@gmail.com>

---------

Co-authored-by: Silvan <silvan.reusser@gmail.com>

internal/api/grpc/server/gateway.go

@@ -7,8 +7,10 @@ import (
 	"strings"
 
 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
+	"github.com/zitadel/logging"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
 	"google.golang.org/protobuf/encoding/protojson"
 
 	client_middleware "github.com/zitadel/zitadel/internal/api/grpc/client/middleware"
@@ -50,26 +52,84 @@ var (
 	)
 )
 
-type Gateway interface {
-	RegisterGateway() GatewayFunc
-	GatewayPathPrefix() string
+type Gateway struct {
+	mux           *runtime.ServeMux
+	http1HostName string
+	connection    *grpc.ClientConn
 }
 
-type GatewayFunc func(ctx context.Context, mux *runtime.ServeMux, endpoint string, opts []grpc.DialOption) error
+func (g *Gateway) Handler() http.Handler {
+	return addInterceptors(g.mux, g.http1HostName)
+}
 
-func CreateGateway(ctx context.Context, g Gateway, port uint16, http1HostName string) (http.Handler, string, error) {
+type RegisterGatewayFunc func(ctx context.Context, mux *runtime.ServeMux, conn *grpc.ClientConn) error
+
+func CreateGatewayWithPrefix(ctx context.Context, g WithGatewayPrefix, port uint16, http1HostName string) (http.Handler, string, error) {
 	runtimeMux := runtime.NewServeMux(serveMuxOptions...)
 	opts := []grpc.DialOption{
 		grpc.WithTransportCredentials(insecure.NewCredentials()),
 		grpc.WithUnaryInterceptor(client_middleware.DefaultTracingClient()),
 	}
-	err := g.RegisterGateway()(ctx, runtimeMux, fmt.Sprintf("localhost:%d", port), opts)
+	connection, err := dial(ctx, port, opts)
+	if err != nil {
+		return nil, "", err
+	}
+	err = g.RegisterGateway()(ctx, runtimeMux, connection)
 	if err != nil {
 		return nil, "", fmt.Errorf("failed to register grpc gateway: %w", err)
 	}
 	return addInterceptors(runtimeMux, http1HostName), g.GatewayPathPrefix(), nil
 }
 
+func CreateGateway(ctx context.Context, port uint16, http1HostName string) (*Gateway, error) {
+	connection, err := dial(ctx,
+		port,
+		[]grpc.DialOption{
+			grpc.WithTransportCredentials(insecure.NewCredentials()),
+			grpc.WithUnaryInterceptor(client_middleware.DefaultTracingClient()),
+		})
+	if err != nil {
+		return nil, err
+	}
+	runtimeMux := runtime.NewServeMux(append(serveMuxOptions, runtime.WithHealthzEndpoint(healthpb.NewHealthClient(connection)))...)
+	return &Gateway{
+		mux:           runtimeMux,
+		http1HostName: http1HostName,
+		connection:    connection,
+	}, nil
+}
+
+func RegisterGateway(ctx context.Context, gateway *Gateway, server Server) error {
+	err := server.RegisterGateway()(ctx, gateway.mux, gateway.connection)
+	if err != nil {
+		return fmt.Errorf("failed to register grpc gateway: %w", err)
+	}
+	return nil
+}
+
+func dial(ctx context.Context, port uint16, opts []grpc.DialOption) (*grpc.ClientConn, error) {
+	endpoint := fmt.Sprintf("localhost:%d", port)
+	conn, err := grpc.Dial(endpoint, opts...)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if err != nil {
+			if cerr := conn.Close(); cerr != nil {
+				logging.Infof("Failed to close conn to %s: %v", endpoint, cerr)
+			}
+			return
+		}
+		go func() {
+			<-ctx.Done()
+			if cerr := conn.Close(); cerr != nil {
+				logging.Infof("Failed to close conn to %s: %v", endpoint, cerr)
+			}
+		}()
+	}()
+	return conn, nil
+}
+
 func addInterceptors(handler http.Handler, http1HostName string) http.Handler {
 	handler = http_mw.CallDurationHandler(handler)
 	handler = http1Host(handler, http1HostName)