Pass environment as SSR component payload for standalone mode

Author: maraf

src/Components/Endpoints/src/DependencyInjection/RazorComponentsServiceCollectionExtensions.cs

@@ -71,6 +71,7 @@ public static IRazorComponentsBuilder AddRazorComponents(this IServiceCollection
         services.TryAddScoped<AuthenticationStateProvider, ServerAuthenticationStateProvider>();
         services.AddSupplyValueFromQueryProvider();
         services.TryAddCascadingValue(sp => sp.GetRequiredService<EndpointHtmlRenderer>().HttpContext);
+        services.TryAddScoped<WebAssemblyEnvironmentEmitter>();
 
         services.TryAddScoped<ResourceCollectionProvider>();
 

src/Components/Endpoints/src/DependencyInjection/WebAssemblyEnvironmentEmitter.cs

@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.Hosting;
+
+namespace Microsoft.AspNetCore.Components.Endpoints;
+
+internal class WebAssemblyEnvironmentEmitter(IHostEnvironment hostEnvironment)
+{
+    private bool wasEmittedAlready;
+
+    public string? GetEnvironmentOnce()
+    {
+        if (wasEmittedAlready)
+        {
+            return null;
+        }
+
+        wasEmittedAlready = true;
+        return hostEnvironment.EnvironmentName;
+    }
+}

src/Components/Endpoints/src/Rendering/SSRRenderModeBoundary.cs

@@ -165,8 +165,8 @@ public ComponentMarker ToMarker(HttpContext httpContext, int sequence, object? c
         var marker = RenderMode switch
         {
             InteractiveServerRenderMode server => ComponentMarker.Create(ComponentMarker.ServerMarkerType, server.Prerender, _markerKey),
-            InteractiveWebAssemblyRenderMode webAssembly => ComponentMarker.Create(ComponentMarker.WebAssemblyMarkerType, webAssembly.Prerender, _markerKey),
-            InteractiveAutoRenderMode auto => ComponentMarker.Create(ComponentMarker.AutoMarkerType, auto.Prerender, _markerKey),
+            InteractiveWebAssemblyRenderMode webAssembly => ComponentMarker.Create(ComponentMarker.WebAssemblyMarkerType, webAssembly.Prerender, _markerKey, GetEnvironmentOnce(httpContext)),
+            InteractiveAutoRenderMode auto => ComponentMarker.Create(ComponentMarker.AutoMarkerType, auto.Prerender, _markerKey, GetEnvironmentOnce(httpContext)),
             _ => throw new UnreachableException($"Unknown render mode {RenderMode.GetType().FullName}"),
         };
 
@@ -188,6 +188,9 @@ public ComponentMarker ToMarker(HttpContext httpContext, int sequence, object? c
         return marker;
     }
 
+    private static string? GetEnvironmentOnce(HttpContext httpContext)
+        => httpContext.RequestServices.GetRequiredService<WebAssemblyEnvironmentEmitter>().GetEnvironmentOnce();
+
     private ComponentMarkerKey GenerateMarkerKey(int sequence, object? componentKey)
     {
         var componentTypeNameHash = _componentTypeNameHashCache.GetOrAdd(_componentType, TypeNameHash.Compute);

src/Components/Web.JS/src/Boot.WebAssembly.Common.ts

@@ -68,23 +68,23 @@ export function setWebAssemblyOptions(initializersReady: Promise<Partial<WebAsse
   }
 }
 
-export function startWebAssembly(components: RootComponentManager<WebAssemblyComponentDescriptor>): Promise<void> {
+export function startWebAssembly(components: RootComponentManager<WebAssemblyComponentDescriptor>, environment: string | undefined): Promise<void> {
   if (startPromise !== undefined) {
     throw new Error('Blazor WebAssembly has already started.');
   }
 
-  startPromise = new Promise(startCore.bind(null, components));
+  startPromise = new Promise(startCore.bind(null, components, environment));
 
   return startPromise;
 }
 
-async function startCore(components: RootComponentManager<WebAssemblyComponentDescriptor>, resolve, _) {
+async function startCore(components: RootComponentManager<WebAssemblyComponentDescriptor>, environment: string | undefined, resolve, _) {
   if (inAuthRedirectIframe()) {
     // eslint-disable-next-line @typescript-eslint/no-empty-function
     await new Promise(() => { }); // See inAuthRedirectIframe for explanation
   }
 
-  const platformLoadPromise = loadWebAssemblyPlatformIfNotStarted();
+  const platformLoadPromise = loadWebAssemblyPlatformIfNotStarted(environment);
 
   addDispatchEventMiddleware((browserRendererId, eventHandlerId, continuation) => {
     // It's extremely unusual, but an event can be raised while we're in the middle of synchronously applying a
@@ -206,10 +206,13 @@ export function waitForBootConfigLoaded(): Promise<MonoConfig> {
   return bootConfigPromise;
 }
 
-export function loadWebAssemblyPlatformIfNotStarted(): Promise<void> {
+export function loadWebAssemblyPlatformIfNotStarted(environment: string | undefined): Promise<void> {
   platformLoadPromise ??= (async () => {
     await initializersPromise;
     const finalOptions = options ?? {};
+    if (!finalOptions.environment) {
+      finalOptions.environment = environment;
+    }
     const existingConfig = options?.configureRuntime;
     finalOptions.configureRuntime = (config) => {
       existingConfig?.(config);

src/Components/Web.JS/src/Boot.WebAssembly.ts

@@ -24,8 +24,20 @@ async function boot(options?: Partial<WebAssemblyStartOptions>): Promise<void> {
 
   JSEventRegistry.create(Blazor);
   const webAssemblyComponents = discoverComponents(document, 'webassembly') as WebAssemblyComponentDescriptor[];
+
   const components = new InitialRootComponentsList(webAssemblyComponents);
-  await startWebAssembly(components);
+  await startWebAssembly(components, findEnvironment(webAssemblyComponents));
+}
+
+function findEnvironment(webAssemblyComponents: WebAssemblyComponentDescriptor[]): string | undefined {
+  for (let index = 0; index < webAssemblyComponents.length; index++) {
+    const component = webAssemblyComponents[index];
+    if (component.environment) {
+      return component.environment;
+    }
+  }
+
+  return undefined;
 }
 
 Blazor.start = boot;

src/Components/Web.JS/src/Services/ComponentDescriptorDiscovery.ts

@@ -355,6 +355,7 @@ type ServerComponentMarker = {
 
 type WebAssemblyComponentMarker = {
   type: 'webassembly';
+  environment: string | undefined;
 } & WebAssemblyMarkerData;
 
 type AutoComponentMarker = {

src/Components/Web.JS/src/Services/WebRootComponentManager.ts

@@ -132,7 +132,8 @@ export class WebRootComponentManager implements DescriptorHandler, RootComponent
 
     setWaitForRootComponents();
 
-    const loadWebAssemblyPromise = loadWebAssemblyPlatformIfNotStarted();
+    // MF TODO: Pass the environment
+    const loadWebAssemblyPromise = loadWebAssemblyPlatformIfNotStarted(undefined);
     const bootConfig = await waitForBootConfigLoaded();
 
     if (maxParallelDownloadsOverride !== undefined) {
@@ -182,7 +183,8 @@ export class WebRootComponentManager implements DescriptorHandler, RootComponent
     this.startLoadingWebAssemblyIfNotStarted();
 
     if (!hasStartedWebAssembly()) {
-      await startWebAssembly(this);
+      // MF TODO: Pass the environment
+      await startWebAssembly(this, undefined);
     }
   }