Support external asset server

v2/pkg/assetserver/assetserver_webview.go

@@ -115,6 +115,10 @@ func (d *AssetServer) processWebViewRequest(r webview.Request) {
 		req.RemoteAddr = "192.0.2.1:1234"
 	}
 
+	if req.RequestURI == "" && req.URL != nil {
+		req.RequestURI = req.URL.String()
+	}
+
 	if req.ContentLength == 0 {
 		req.ContentLength, _ = strconv.ParseInt(req.Header.Get(HeaderContentLength), 10, 64)
 	} else {

v3/internal/assetserver/assethandler.go

@@ -78,11 +78,11 @@ func (d *assetHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	if strings.EqualFold(req.Method, http.MethodGet) {
 		filename := path.Clean(strings.TrimPrefix(url, "/"))
 
-		d.logDebug("Handling request '%s' (file='%s')", url, filename)
+		d.logInfo("Handling request", "url", url, "file", filename)
 		if err := d.serveFSFile(rw, req, filename); err != nil {
 			if os.IsNotExist(err) {
 				if handler != nil {
-					d.logDebug("File '%s' not found, serving '%s' by AssetHandler", filename, url)
+					d.logInfo("File not found. Deferring to AssetHandler", "filename", filename, "url", url)
 					handler.ServeHTTP(rw, req)
 					err = nil
 				} else {
@@ -97,7 +97,7 @@ func (d *assetHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 			}
 		}
 	} else if handler != nil {
-		d.logDebug("No GET request, serving '%s' by AssetHandler", url)
+		d.logInfo("Non-GET request. Deferring to AssetHandler", "url", url)
 		handler.ServeHTTP(rw, req)
 	} else {
 		rw.WriteHeader(http.StatusMethodNotAllowed)
@@ -185,14 +185,10 @@ func (d *assetHandler) serveFSFile(rw http.ResponseWriter, req *http.Request, fi
 	return err
 }
 
-func (d *assetHandler) logDebug(message string, args ...interface{}) {
+func (d *assetHandler) logInfo(message string, args ...interface{}) {
-	if d.logger != nil {
 	d.logger.Debug("[AssetHandler] "+message, args...)
 }
-}
 
 func (d *assetHandler) logError(message string, args ...interface{}) {
-	if d.logger != nil {
 	d.logger.Error("[AssetHandler] "+message, args...)
 }
-}

v3/internal/assetserver/assetserver.go

@@ -7,6 +7,7 @@ import (
 	"math/rand"
 	"net/http"
 	"net/http/httptest"
+	"net/http/httputil"
 	"strings"
 
 	"golang.org/x/net/html"
@@ -38,6 +39,7 @@ type AssetServer struct {
 
 	logger  *slog.Logger
 	runtime RuntimeAssets
+	options *Options
 
 	servingFromDisk bool
 
@@ -53,6 +55,9 @@ type AssetServer struct {
 	// GetFlags returns the application flags
 	GetFlags func() []byte
 
+	// External dev server proxy
+	wsHandler *httputil.ReverseProxy
+
 	assetServerWebView
 }
 
@@ -62,10 +67,6 @@ func NewAssetServer(options *Options, servingFromDisk bool, logger *slog.Logger,
 		return nil, err
 	}
 
-	return NewAssetServerWithHandler(handler, servingFromDisk, logger, runtime, debug, runtimeHandler)
-}
-
-func NewAssetServerWithHandler(handler http.Handler, servingFromDisk bool, logger *slog.Logger, runtime RuntimeAssets, debug bool, runtimeHandler RuntimeHandler) (*AssetServer, error) {
 	var buffer bytes.Buffer
 	buffer.Write(runtime.RuntimeDesktopJS())
 
@@ -73,6 +74,7 @@ func NewAssetServerWithHandler(handler http.Handler, servingFromDisk bool, logge
 		handler:        handler,
 		runtimeJS:      buffer.Bytes(),
 		runtimeHandler: runtimeHandler,
+		options:        options,
 
 		// Check if we have been given a directory to serve assets from.
 		// If so, this means we are in dev mode and are serving assets off disk.
@@ -84,9 +86,44 @@ func NewAssetServerWithHandler(handler http.Handler, servingFromDisk bool, logge
 		debug:           debug,
 	}
 
+	// Check if proxy required
+	externalURL, err := options.getExternalURL()
+	if err != nil {
+		return nil, err
+	} else {
+		result.wsHandler = httputil.NewSingleHostReverseProxy(externalURL)
+		err := result.checkExternalURL()
+		if err != nil {
+			return nil, err
+		}
+	}
 	return result, nil
 }
 
+func (d *AssetServer) checkExternalURL() error {
+	req, err := http.NewRequest("OPTIONS", "/", nil)
+	if err != nil {
+		return err
+	}
+	w := httptest.NewRecorder()
+	d.wsHandler.ServeHTTP(w, req)
+	if w.Code != http.StatusNoContent {
+		return fmt.Errorf("unable to connect to external server: %s. Please check it's running.", d.options.ExternalURL)
+	}
+	return nil
+}
+
+func (d *AssetServer) LogDetails() {
+	if d.debug {
+		d.logger.Info("AssetServer Info:",
+			"assetsFS", d.options.Assets != nil,
+			"middleware", d.options.Middleware != nil,
+			"handler", d.options.Handler != nil,
+			"externalURL", d.options.ExternalURL,
+		)
+	}
+}
+
 func (d *AssetServer) AddPluginScript(pluginName string, script string) {
 	if d.pluginScripts == nil {
 		d.pluginScripts = make(map[string]string)
@@ -97,11 +134,23 @@ func (d *AssetServer) AddPluginScript(pluginName string, script string) {
 	d.pluginScripts[pluginScriptName] = script
 }
 
+func (d *AssetServer) logRequest(req *http.Request, code int) {
+	d.logger.Info("AssetServer:", "code", code, "method", req.Method, "url", req.URL.Path)
+}
+
 func (d *AssetServer) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+
+	if d.wsHandler != nil {
+		d.wsHandler.ServeHTTP(rw, req)
+		// Get response code from header
+		code := rw.(*contentTypeSniffer).rw.(*legacyRequestNoOpCloserResponseWriter).ResponseWriter.(*httptest.ResponseRecorder).Code
+		d.logRequest(req, code)
+		return
+	} else {
 		if isWebSocket(req) {
 			// WebSockets are not supported by the AssetServer
 			rw.WriteHeader(http.StatusNotImplemented)
-		return
+		}
 	}
 
 	header := rw.Header()
@@ -223,14 +272,10 @@ func (d *AssetServer) serveError(rw http.ResponseWriter, err error, msg string,
 	rw.WriteHeader(http.StatusInternalServerError)
 }
 
-func (d *AssetServer) logDebug(message string, args ...interface{}) {
+func (d *AssetServer) logInfo(message string, args ...interface{}) {
-	if d.logger != nil {
+	d.logger.Info("AssetServer: "+message, args...)
-		d.logger.Debug("[AssetServer] "+message, args...)
-	}
 }
 
 func (d *AssetServer) logError(message string, args ...interface{}) {
-	if d.logger != nil {
+	d.logger.Error("AssetServer: "+message, args...)
-		d.logger.Error("[AssetServer] "+message, args...)
-	}
 }

v3/internal/assetserver/assetserver_dev.go

@@ -2,29 +2,23 @@
 
 package assetserver
 
-import (
-	"log/slog"
-	"net/http"
-	"strings"
-)
-
 /*
 The assetserver for the dev mode.
 Depending on the UserAgent it injects a websocket based IPC script into `index.html` or the default desktop IPC. The
 default desktop IPC is injected when the webview accesses the devserver.
 */
-func NewDevAssetServer(handler http.Handler, servingFromDisk bool, logger *slog.Logger, runtime RuntimeAssets, runtimeHandler RuntimeHandler) (*AssetServer, error) {
+//func NewDevAssetServer(handler http.Handler, servingFromDisk bool, logger *slog.Logger, runtime RuntimeAssets, runtimeHandler RuntimeHandler) (*AssetServer, error) {
-	result, err := NewAssetServerWithHandler(handler, servingFromDisk, logger, runtime, true, runtimeHandler)
+//	result, err := NewAssetServerWithHandler(handler, servingFromDisk, logger, runtime, true, runtimeHandler)
-	if err != nil {
+//	if err != nil {
-		return nil, err
+//		return nil, err
-	}
+//	}
-
+//
-	result.ipcJS = func(req *http.Request) []byte {
+//	result.ipcJS = func(req *http.Request) []byte {
-		if strings.Contains(req.UserAgent(), WailsUserAgentValue) {
+//		if strings.Contains(req.UserAgent(), WailsUserAgentValue) {
-			return runtime.DesktopIPC()
+//			return runtime.DesktopIPC()
-		}
+//		}
-		return runtime.WebsocketIPC()
+//		return runtime.WebsocketIPC()
-	}
+//	}
-
+//
-	return result, nil
+//	return result, nil
-}
+//}

v3/internal/assetserver/assetserver_webview.go

@@ -63,7 +63,7 @@ func (d *AssetServer) processWebViewRequest(r webview.Request) {
 
 	uri, err := r.URL()
 	if err != nil {
-		d.logError("Error processing request, unable to get URL: %s (HttpResponse=500)", err)
+		d.logError("Error processing request, unable to get URL (HttpResponse=500)", "error", err.Error())
 		http.Error(rw, err.Error(), http.StatusInternalServerError)
 		return
 	}
@@ -96,6 +96,18 @@ func (d *AssetServer) processWebViewRequest(r webview.Request) {
 		d.webviewRequestErrorHandler(uri, rw, fmt.Errorf("HTTP-Request: %w", err))
 		return
 	}
+
+	// For server requests, the URL is parsed from the URI supplied on the Request-Line as stored in RequestURI. For
+	// most requests, fields other than Path and RawQuery will be empty. (See RFC 7230, Section 5.3)
+	req.URL.Scheme = ""
+	req.URL.Host = ""
+	req.URL.Fragment = ""
+	req.URL.RawFragment = ""
+
+	if url := req.URL; req.RequestURI == "" && url != nil {
+		req.RequestURI = url.String()
+	}
+
 	req.Header = header
 
 	if req.RemoteAddr == "" {
@@ -131,7 +143,7 @@ func (d *AssetServer) webviewRequestErrorHandler(uri string, rw http.ResponseWri
 		logInfo = strings.Replace(logInfo, fmt.Sprintf("%s://%s", uri.Scheme, uri.Host), "", 1)
 	}
 
-	d.logError("Error processing request '%s': %s (HttpResponse=500)", logInfo, err)
+	d.logError("Error processing request (HttpResponse=500)", "details", logInfo, "error", err.Error())
 	http.Error(rw, err.Error(), http.StatusInternalServerError)
 }
 

v3/internal/assetserver/options.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io/fs"
 	"net/http"
+	"net/url"
 )
 
 // Options defines the configuration of the AssetServer.
@@ -33,6 +34,10 @@ type Options struct {
 	// Multiple Middlewares can be chained together with:
 	//   ChainMiddleware(middleware ...Middleware) Middleware
 	Middleware Middleware
+
+	// ExternalURL is the URL that the assets are served from
+	// This is useful when using a development server like `vite` or `snowpack` which serves the assets on a different port.
+	ExternalURL string
 }
 
 // Validate the options
@@ -43,3 +48,10 @@ func (o Options) Validate() error {
 
 	return nil
 }
+
+func (o Options) getExternalURL() (*url.URL, error) {
+	if o.ExternalURL == "" {
+		return nil, nil
+	}
+	return url.Parse(o.ExternalURL)
+}

v3/pkg/application/application.go

@@ -57,6 +57,7 @@ func New(appOptions Options) *App {
 		Assets:      appOptions.Assets.FS,
 		Handler:     appOptions.Assets.Handler,
 		Middleware:  assetserver.Middleware(appOptions.Assets.Middleware),
+		ExternalURL: appOptions.Assets.ExternalURL,
 	}
 
 	srv, err := assetserver.NewAssetServer(opts, false, result.Logger, wailsruntime.RuntimeAssetsBundle, result.isDebugMode, NewMessageProcessor())
@@ -112,7 +113,6 @@ func mergeApplicationDefaults(o *Options) {
 	if o.Icon == nil {
 		o.Icon = icons.ApplicationLightMode256
 	}
-
 }
 
 type (
@@ -388,6 +388,7 @@ func (a *App) NewSystemTray() *SystemTray {
 func (a *App) Run() error {
 	a.logStartup()
 	a.logPlatformInfo()
+	a.assets.LogDetails()
 
 	// Setup panic handler
 	defer processPanicHandlerRecover()

v3/pkg/application/options_application.go

@@ -62,6 +62,10 @@ type AssetOptions struct {
 	// Multiple Middlewares can be chained together with:
 	//   ChainMiddleware(middleware ...Middleware) Middleware
 	Middleware Middleware
+
+	// External URL can be set to a development server URL so that all requests are forwarded to it. This is useful
+	// when using a development server like `vite` or `snowpack` which serves the assets on a different port.
+	ExternalURL string
 }
 
 // Middleware defines a HTTP middleware that can be applied to the AssetServer.

v3/pkg/application/webview_window_windows.go

@@ -1238,6 +1238,12 @@ func coreWebview2RequestToHttpRequest(coreReq *edge.ICoreWebView2WebResourceRequ
 			}
 		}
 
+		// WebView2 has problems when a request returns a 304 status code and the WebView2 is going to hang for other
+		// requests including IPC calls.
+		// So prevent 304 status codes by removing the headers that are used in combination with caching.
+		header.Del("If-Modified-Since")
+		header.Del("If-None-Match")
+
 		method, err := coreReq.GetMethod()
 		if err != nil {
 			return nil, fmt.Errorf("GetMethod Error: %s", err)
@@ -1334,8 +1340,16 @@ func (w *windowsWebviewWindow) processRequest(req *edge.ICoreWebView2WebResource
 		headers = append(headers, fmt.Sprintf("%s: %s", k, strings.Join(v, ",")))
 	}
 
+	code := rw.Code
+	if code == http.StatusNotModified {
+		// WebView2 has problems when a request returns a 304 status code and the WebView2 is going to hang for other
+		// requests including IPC calls.
+		globalApplication.error("AssetServer returned 304 - StatusNotModified which is going to hang WebView2, changed code to 505 - StatusInternalServerError", "uri", uri)
+		code = http.StatusInternalServerError
+	}
+
 	env := w.chromium.Environment()
-	response, err := env.CreateWebResourceResponse(rw.Body.Bytes(), rw.Code, http.StatusText(rw.Code), strings.Join(headers, "\n"))
+	response, err := env.CreateWebResourceResponse(rw.Body.Bytes(), code, http.StatusText(code), strings.Join(headers, "\n"))
 	if err != nil {
 		globalApplication.error("CreateWebResourceResponse Error: " + err.Error())
 		return
@@ -1447,7 +1461,9 @@ func (w *windowsWebviewWindow) setupChromium() {
 		chromium.NavigateToString(w.parent.options.HTML)
 	} else {
 		var startURL = "http://wails.localhost"
-		if w.parent.options.URL != "" {
+		if globalApplication.options.Assets.ExternalURL != "" {
+			startURL = globalApplication.options.Assets.ExternalURL
+		} else if w.parent.options.URL != "" {
 			// parse the url
 			parsedURL, err := url.Parse(w.parent.options.URL)
 			if err != nil {