[browser] Generate boot config as javascript module

src/mono/browser/runtime/dotnet.d.ts

@@ -292,7 +292,10 @@ type ResourceList = {
  * @returns A URI string or a Response promise to override the loading process, or null/undefined to allow the default loading behavior.
  * When returned string is not qualified with `./` or absolute URL, it will be resolved against the application base URI.
  */
-type LoadBootResourceCallback = (type: WebAssemblyBootResourceType, name: string, defaultUri: string, integrity: string, behavior: AssetBehaviors) => string | Promise<Response> | null | undefined;
+type LoadBootResourceCallback = (type: WebAssemblyBootResourceType, name: string, defaultUri: string, integrity: string, behavior: AssetBehaviors) => string | Promise<Response> | Promise<BootModule> | null | undefined;
+type BootModule = {
+    config: MonoConfig;
+};
 interface LoadingResource {
     name: string;
     url: string;

src/mono/browser/runtime/loader/assets.ts

@@ -4,7 +4,7 @@
 import WasmEnableThreads from "consts:wasmEnableThreads";
 
 import { PThreadPtrNull, type AssetEntryInternal, type PThreadWorker, type PromiseAndController } from "../types/internal";
-import { type AssetBehaviors, type AssetEntry, type LoadingResource, type ResourceList, type SingleAssetBehaviors as SingleAssetBehaviors, type WebAssemblyBootResourceType } from "../types";
+import { BootModule, type AssetBehaviors, type AssetEntry, type LoadingResource, type ResourceList, type SingleAssetBehaviors as SingleAssetBehaviors, type WebAssemblyBootResourceType } from "../types";
 import { ENVIRONMENT_IS_NODE, ENVIRONMENT_IS_SHELL, ENVIRONMENT_IS_WEB, ENVIRONMENT_IS_WORKER, loaderHelpers, mono_assert, runtimeHelpers } from "./globals";
 import { createPromiseController } from "./promise-controller";
 import { mono_log_debug, mono_log_warn } from "./logging";
@@ -725,7 +725,7 @@ function fetchResource (asset: AssetEntryInternal): Promise<Response> {
         const customLoadResult = invokeLoadBootResource(asset);
         if (customLoadResult instanceof Promise) {
             // They are supplying an entire custom response, so just use that
-            return customLoadResult;
+            return customLoadResult as Promise<Response>;
         } else if (typeof customLoadResult === "string") {
             url = customLoadResult;
         }
@@ -766,7 +766,7 @@ const monoToBlazorAssetTypeMap: { [key: string]: WebAssemblyBootResourceType | u
     "js-module-threads": "dotnetjs"
 };
 
-function invokeLoadBootResource (asset: AssetEntryInternal): string | Promise<Response> | null | undefined {
+function invokeLoadBootResource (asset: AssetEntryInternal): string | Promise<Response> | Promise<BootModule> | null | undefined {
     if (loaderHelpers.loadBootResource) {
         const requestHash = asset.hash ?? "";
         const url = asset.resolvedUrl!;

src/mono/browser/runtime/loader/config.ts

@@ -5,7 +5,7 @@ import BuildConfiguration from "consts:configuration";
 import WasmEnableThreads from "consts:wasmEnableThreads";
 
 import { type DotnetModuleInternal, type MonoConfigInternal, JSThreadBlockingMode } from "../types/internal";
-import type { DotnetModuleConfig, MonoConfig, ResourceGroups, ResourceList } from "../types";
+import type { BootModule, DotnetModuleConfig, MonoConfig, ResourceGroups, ResourceList } from "../types";
 import { exportedRuntimeAPI, loaderHelpers, runtimeHelpers } from "./globals";
 import { mono_log_error, mono_log_debug } from "./logging";
 import { importLibraryInitializers, invokeLibraryInitializers } from "./libraryInitializers";
@@ -240,7 +240,10 @@ export async function mono_wasm_load_config (module: DotnetModuleInternal): Prom
     try {
         if (!module.configSrc && (!loaderHelpers.config || Object.keys(loaderHelpers.config).length === 0 || (!loaderHelpers.config.assets && !loaderHelpers.config.resources))) {
             // if config file location nor assets are provided
-            module.configSrc = "./blazor.boot.json";
+            // Temporal way for tests to opt-in for using boot.js
+            module.configSrc = (globalThis as any)["__DOTNET_INTERNAL_BOOT_CONFIG_SRC"]
+                ?? globalThis.window?.document?.documentElement?.getAttribute("data-dotnet_internal_boot_config_src")
+                ?? "./blazor.boot.json";
         }
 
         configFilePath = module.configSrc;
@@ -289,24 +292,45 @@ export function isDebuggingSupported (): boolean {
 async function loadBootConfig (module: DotnetModuleInternal): Promise<void> {
     const defaultConfigSrc = loaderHelpers.locateFile(module.configSrc!);
 
-    const loaderResponse = loaderHelpers.loadBootResource !== undefined ?
-        loaderHelpers.loadBootResource("manifest", "blazor.boot.json", defaultConfigSrc, "", "manifest") :
-        defaultLoadBootConfig(defaultConfigSrc);
-
-    let loadConfigResponse: Response;
+    let loaderResponse = null;
+    if (loaderHelpers.loadBootResource !== undefined) {
+        loaderResponse = loaderHelpers.loadBootResource("manifest", "blazor.boot.json", defaultConfigSrc, "", "manifest");
+    }
 
+    let loadedConfigResponse: Response | null = null;
+    let loadedConfig: MonoConfig;
     if (!loaderResponse) {
-        loadConfigResponse = await defaultLoadBootConfig(appendUniqueQuery(defaultConfigSrc, "manifest"));
+        if (defaultConfigSrc.includes(".json")) {
+            loadedConfigResponse = await fetchBootConfig(appendUniqueQuery(defaultConfigSrc, "manifest"));
+            loadedConfig = await readBootConfigResponse(loadedConfigResponse);
+        } else {
+            loadedConfig = (await import(appendUniqueQuery(defaultConfigSrc, "manifest"))).config;
+        }
     } else if (typeof loaderResponse === "string") {
-        loadConfigResponse = await defaultLoadBootConfig(makeURLAbsoluteWithApplicationBase(loaderResponse));
+        if (loaderResponse.includes(".json")) {
+            loadedConfigResponse = await fetchBootConfig(makeURLAbsoluteWithApplicationBase(loaderResponse));
+            loadedConfig = await readBootConfigResponse(loadedConfigResponse);
+        } else {
+            loadedConfig = (await import(makeURLAbsoluteWithApplicationBase(loaderResponse))).config;
+        }
     } else {
-        loadConfigResponse = await loaderResponse;
+        const loadedResponse = await loaderResponse;
+        if (typeof (loadedResponse as Response).json == "function") {
+            loadedConfigResponse = loadedResponse as Response;
+            loadedConfig = await readBootConfigResponse(loadedConfigResponse);
+        } else {
+            // If the response doesn't contain .json(), consider it an imported module.
+            loadedConfig = (loadedResponse as BootModule).config;
+        }
     }
 
-    const loadedConfig: MonoConfig = await readBootConfigResponse(loadConfigResponse);
     deep_merge_config(loaderHelpers.config, loadedConfig);
 
-    function defaultLoadBootConfig (url: string): Promise<Response> {
+    if (!loaderHelpers.config.applicationEnvironment) {
+        loaderHelpers.config.applicationEnvironment = "Production";
+    }
+
+    function fetchBootConfig (url: string): Promise<Response> {
         return loaderHelpers.fetch_like(url, {
             method: "GET",
             credentials: "include",
@@ -320,7 +344,7 @@ async function readBootConfigResponse (loadConfigResponse: Response): Promise<Mo
     const loadedConfig: MonoConfig = await loadConfigResponse.json();
 
     if (!config.applicationEnvironment) {
-        loadedConfig.applicationEnvironment = loadConfigResponse.headers.get("Blazor-Environment") || loadConfigResponse.headers.get("DotNet-Environment") || "Production";
+        loadedConfig.applicationEnvironment = loadConfigResponse.headers.get("Blazor-Environment") || loadConfigResponse.headers.get("DotNet-Environment") || undefined;
     }
 
     if (!loadedConfig.environmentVariables)

src/mono/browser/runtime/types/index.ts

@@ -244,7 +244,11 @@ export type ResourceList = { [name: string]: string | null | "" };
  * @returns A URI string or a Response promise to override the loading process, or null/undefined to allow the default loading behavior.
  * When returned string is not qualified with `./` or absolute URL, it will be resolved against the application base URI.
  */
-export type LoadBootResourceCallback = (type: WebAssemblyBootResourceType, name: string, defaultUri: string, integrity: string, behavior: AssetBehaviors) => string | Promise<Response> | null | undefined;
+export type LoadBootResourceCallback = (type: WebAssemblyBootResourceType, name: string, defaultUri: string, integrity: string, behavior: AssetBehaviors) => string | Promise<Response> | Promise<BootModule> | null | undefined;
+
+export type BootModule = {
+    config: MonoConfig
+}
 
 export interface LoadingResource {
     name: string;

src/mono/wasm/Wasm.Build.Tests/Blazor/MiscTests.cs

@@ -87,7 +87,7 @@ public void BugRegression_60479_WithRazorClassLib()
         BlazorBuild(info, config);
 
         // will relink
-        BlazorPublish(info, config, new PublishOptions(UseCache: false));
+        BlazorPublish(info, config, new PublishOptions(UseCache: false, BootConfigFileName: "blazor.boot.json"));
 
         // publish/wwwroot/_framework/blazor.boot.json
         string frameworkDir = GetBlazorBinFrameworkDir(config, forPublish: true);

src/mono/wasm/Wasm.Build.Tests/BrowserStructures/BuildOptions.cs

@@ -23,7 +23,7 @@ public BuildOptions(
         bool WarnAsError                                            = true,
         RuntimeVariant RuntimeType                                  = RuntimeVariant.SingleThreaded,
         IDictionary<string, string>? ExtraBuildEnvironmentVariables = null,
-        string BootConfigFileName                                   = "blazor.boot.json",
+        string BootConfigFileName                                   = "dotnet.boot.js",
         string NonDefaultFrameworkDir                               = "",
         string ExtraMSBuildArgs                                     = "",
         bool FeaturePerfTracing                                     = false

src/mono/wasm/Wasm.Build.Tests/BrowserStructures/MSBuildOptions.cs

@@ -22,7 +22,7 @@ public abstract record MSBuildOptions
     bool                            WarnAsError                     = true,
     RuntimeVariant                  RuntimeType                     = RuntimeVariant.SingleThreaded,
     IDictionary<string, string>?    ExtraBuildEnvironmentVariables  = null,
-    string                          BootConfigFileName              = "blazor.boot.json",
+    string                          BootConfigFileName              = "dotnet.boot.js",
     string                          NonDefaultFrameworkDir          = "",
     string                          ExtraMSBuildArgs                = "",
     bool                            FeaturePerfTracing              = false

src/mono/wasm/Wasm.Build.Tests/BrowserStructures/PublishOptions.cs

@@ -26,7 +26,7 @@ public PublishOptions(
         bool WarnAsError                                            = true,
         RuntimeVariant RuntimeType                                  = RuntimeVariant.SingleThreaded,
         IDictionary<string, string>? ExtraBuildEnvironmentVariables = null,
-        string BootConfigFileName                                   = "blazor.boot.json",
+        string BootConfigFileName                                   = "dotnet.boot.js",
         string NonDefaultFrameworkDir                               = "",
         string ExtraMSBuildArgs                                     = "",
         bool BuildOnlyAfterPublish                                  = true,

src/mono/wasm/Wasm.Build.Tests/ModuleConfigTests.cs

@@ -83,15 +83,12 @@ public async Task OutErrOverrideWorks()
     [InlineData(Configuration.Release, false)]
     public async Task OverrideBootConfigName(Configuration config, bool isPublish)
     {
-        ProjectInfo info = CopyTestAsset(config, false, TestAsset.WasmBasicTestApp, "OverrideBootConfigName");
-        (string _, string _) = isPublish ?
-            PublishProject(info, config) :
-            BuildProject(info, config);
+        ProjectInfo info = CopyTestAsset(config, false, TestAsset.WasmBasicTestApp, $"OverrideBootConfigName_{isPublish}");
 
-        string extraArgs = "-p:WasmBootConfigFileName=boot.json";
-        (string _, string _) = isPublish ?
-            PublishProject(info, config, new PublishOptions(BootConfigFileName: "boot.json", UseCache: false, ExtraMSBuildArgs: extraArgs)) :
-            BuildProject(info, config, new BuildOptions(BootConfigFileName: "boot.json", UseCache: false, ExtraMSBuildArgs: extraArgs));
+        if (isPublish)
+            PublishProject(info, config, new PublishOptions(BootConfigFileName: "boot.json", UseCache: false));
+        else
+            BuildProject(info, config, new BuildOptions(BootConfigFileName: "boot.json", UseCache: false));
 
         var runOptions = new BrowserRunOptions(
             Configuration: config,

src/mono/wasm/Wasm.Build.Tests/ProjectProviderBase.cs

@@ -315,7 +315,7 @@ private string[] GetFilesMatchingNameConsideringFingerprinting(string filePath,
 
         // filter files with a single fingerprint segment, e.g. "dotnet*.js" should not catch "dotnet.native.d1au9i.js" but should catch "dotnet.js"
         string pattern = $@"^{Regex.Escape(fileNameWithoutExtensionAndFingerprinting)}(\.[^.]+)?{Regex.Escape(fileExtension)}$";
-        var tmp = files.Where(f => Regex.IsMatch(Path.GetFileName(f), pattern)).ToArray();
+        var tmp = files.Where(f => Regex.IsMatch(Path.GetFileName(f), pattern)).Where(f => !f.Contains("dotnet.boot")).ToArray();
         return tmp;
     }
 
@@ -373,7 +373,7 @@ private string[] GetFilesMatchingNameConsideringFingerprinting(string filePath,
 
         if (IsFingerprintingEnabled)
         {
-            string bootJsonPath = Path.Combine(paths.BinFrameworkDir, "blazor.boot.json");
+            string bootJsonPath = Path.Combine(paths.BinFrameworkDir, "dotnet.boot.js");
             BootJsonData bootJson = GetBootJson(bootJsonPath);
             var keysToUpdate = new List<string>();
             var updates = new List<(string oldKey, string newKey, (string fullPath, bool unchanged) value)>();
@@ -524,8 +524,8 @@ public BootJsonData AssertBootJson(AssertBundleOptions options)
         var knownSet = GetAllKnownDotnetFilesToFingerprintMap(options);
         foreach (string expectedFilename in expected)
         {
-            // FIXME: Find a systematic solution for skipping dotnet.js from boot json check
-            if (expectedFilename == "dotnet.js" || Path.GetExtension(expectedFilename) == ".map")
+            // FIXME: Find a systematic solution for skipping dotnet.js & dotnet.boot.js from boot json check
+            if (expectedFilename == "dotnet.js" || expectedFilename == "dotnet.boot.js" || Path.GetExtension(expectedFilename) == ".map")
                 continue;
 
             bool expectFingerprint = knownSet[expectedFilename];
@@ -568,17 +568,40 @@ public BootJsonData AssertBootJson(AssertBundleOptions options)
         return bootJson;
     }
 
-    public static BootJsonData ParseBootData(string bootJsonPath)
+    public static BootJsonData ParseBootData(string bootConfigPath)
     {
-        using FileStream stream = File.OpenRead(bootJsonPath);
-        stream.Position = 0;
-        var serializer = new DataContractJsonSerializer(
-            typeof(BootJsonData),
-            new DataContractJsonSerializerSettings { UseSimpleDictionaryFormat = true });
-
-        var config = (BootJsonData?)serializer.ReadObject(stream);
-        Assert.NotNull(config);
-        return config;
+        string startComment = "/*json-start*/";
+        string endComment = "/*json-end*/";
+
+        string moduleContent = File.ReadAllText(bootConfigPath);
+        int startCommentIndex = moduleContent.IndexOf(startComment);
+        int endCommentIndex = moduleContent.IndexOf(endComment);
+        if (startCommentIndex >= 0 && endCommentIndex >= 0)
+        {
+            // boot.js
+            int startJsonIndex = startCommentIndex + startComment.Length;
+            string jsonContent = moduleContent.Substring(startJsonIndex, endCommentIndex - startJsonIndex);
+            using var ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonContent));
+            ms.Position = 0;
+            return LoadConfig(ms);
+        }
+        else
+        {
+            using FileStream stream = File.OpenRead(bootConfigPath);
+            stream.Position = 0;
+            return LoadConfig(stream);
+        }
+
+        static BootJsonData LoadConfig(Stream stream)
+        {
+            var serializer = new DataContractJsonSerializer(
+                typeof(BootJsonData),
+                new DataContractJsonSerializerSettings { UseSimpleDictionaryFormat = true });
+
+            var config = (BootJsonData?)serializer.ReadObject(stream);
+            Assert.NotNull(config);
+            return config;
+        }
     }
 
     private void AssertFileNames(IEnumerable<string> expected, IEnumerable<string> actual)

src/mono/wasm/Wasm.Build.Tests/Templates/WasmTemplateTestsBase.cs

@@ -80,11 +80,28 @@ public ProjectInfo CreateWasmTemplateProject(
             .ExecuteWithCapturedOutput($"new {template.ToString().ToLower()} {extraArgs}")
             .EnsureSuccessful();
 
+        UpdateBootJsInHtmlFiles();
+
         string projectFilePath = Path.Combine(_projectDir, $"{projectName}.csproj");
         UpdateProjectFile(projectFilePath, runAnalyzers, extraProperties, extraItems, insertAtEnd);
         return new ProjectInfo(projectName, projectFilePath, logPath, nugetDir);
     }
 
+    protected void UpdateBootJsInHtmlFiles()
+    {
+        foreach (var filePath in Directory.EnumerateFiles(_projectDir, "*.html", SearchOption.AllDirectories))
+        {
+            UpdateBootJsInHtmlFile(filePath);
+        }
+    }
+
+    protected void UpdateBootJsInHtmlFile(string filePath)
+    {
+        string fileContent = File.ReadAllText(filePath);
+        fileContent = StringReplaceWithAssert(fileContent, "<head>", "<head><script>window['__DOTNET_INTERNAL_BOOT_CONFIG_SRC'] = 'dotnet.boot.js';</script>");
+        File.WriteAllText(filePath, fileContent);
+    }
+
     protected ProjectInfo CopyTestAsset(
         Configuration config,
         bool aot,
@@ -163,6 +180,8 @@ public virtual (string projectDir, string buildOutput) BuildProject(
 
         buildOptions.ExtraBuildEnvironmentVariables["TreatPreviousAsCurrent"] = "false";
 
+        buildOptions = buildOptions with { ExtraMSBuildArgs = $"{buildOptions.ExtraMSBuildArgs} -p:WasmBootConfigFileName={buildOptions.BootConfigFileName}" };
+
         (CommandResult res, string logFilePath) = BuildProjectWithoutAssert(configuration, info.ProjectName, buildOptions);
 
         if (buildOptions.UseCache)

src/mono/wasm/Wasm.Build.Tests/WasmRunOutOfAppBundleTests.cs

@@ -34,10 +34,12 @@ public async void RunOutOfAppBundle(Configuration config, bool aot)
         string relativeMainJsPath = "./wwwroot/main.js";
         if (!File.Exists(indexHtmlPath))
         {
-            var html = $@"<!DOCTYPE html><html><body><script type=""module"" src=""{relativeMainJsPath}""></script></body></html>";
+            var html = $@"<!DOCTYPE html><html><head></head><body><script type=""module"" src=""{relativeMainJsPath}""></script></body></html>";
             File.WriteAllText(indexHtmlPath, html);
         }
 
+        UpdateBootJsInHtmlFile(indexHtmlPath);
+
         RunResult result = await RunForPublishWithWebServer(new BrowserRunOptions(
                 config,
                 TestScenario: "DotnetRun",