Validate TypeScript AppHosts before startup

src/Aspire.Cli/Projects/GuestRuntime.cs

@@ -136,10 +136,21 @@ public GuestRuntime(RuntimeSpec spec, ILogger logger, FileLoggerProvider? fileLo
         IGuestProcessLauncher launcher,
         CancellationToken cancellationToken)
     {
-        var commandSpec = watchMode && _spec.WatchExecute is not null
-            ? _spec.WatchExecute
+        var useWatchCommand = watchMode && _spec.WatchExecute is not null;
+        var commandSpec = useWatchCommand
+            ? _spec.WatchExecute!
             : _spec.Execute;
 
+        await EnsureMigrationFilesExistAsync(directory, cancellationToken);
+        if (!useWatchCommand)
+        {
+            var preExecuteResult = await RunPreExecuteCommandsAsync(appHostFile, directory, environmentVariables, launcher, cancellationToken);
+            if (preExecuteResult.ExitCode != 0)
+            {
+                return preExecuteResult;
+            }
+        }
+
         return await ExecuteCommandAsync(commandSpec, appHostFile, directory, environmentVariables, null, launcher, cancellationToken);
     }
 
@@ -163,9 +174,45 @@ public GuestRuntime(RuntimeSpec spec, ILogger logger, FileLoggerProvider? fileLo
     {
         var commandSpec = _spec.PublishExecute ?? _spec.Execute;
 
+        await EnsureMigrationFilesExistAsync(directory, cancellationToken);
+        var preExecuteResult = await RunPreExecuteCommandsAsync(appHostFile, directory, environmentVariables, launcher, cancellationToken);
+        if (preExecuteResult.ExitCode != 0)
+        {
+            return preExecuteResult;
+        }
+
         return await ExecuteCommandAsync(commandSpec, appHostFile, directory, environmentVariables, publishArgs, launcher, cancellationToken);
     }
 
+    private async Task<(int ExitCode, OutputCollector? Output)> RunPreExecuteCommandsAsync(
+        FileInfo appHostFile,
+        DirectoryInfo directory,
+        IDictionary<string, string> environmentVariables,
+        IGuestProcessLauncher launcher,
+        CancellationToken cancellationToken)
+    {
+        if (_spec.PreExecute is null or { Length: 0 })
+        {
+            return (0, new OutputCollector());
+        }
+
+        var preExecuteLauncher = launcher is ExtensionGuestLauncher ? CreateDefaultLauncher() : launcher;
+        foreach (var commandSpec in _spec.PreExecute)
+        {
+            var args = ReplacePlaceholders(commandSpec.Args, appHostFile, directory, null);
+            var mergedEnvironment = MergeEnvironmentVariables(environmentVariables, commandSpec);
+
+            _logger.LogDebug("Launching pre-execution command: {Command} {Args}", commandSpec.Command, string.Join(" ", args));
+            var (exitCode, output) = await preExecuteLauncher.LaunchAsync(commandSpec.Command, args, directory, mergedEnvironment, cancellationToken);
+            if (exitCode != 0)
+            {
+                return (exitCode, output ?? new OutputCollector());
+            }
+        }
+
+        return (0, new OutputCollector());
+    }
+
     private async Task<(int ExitCode, OutputCollector? Output)> ExecuteCommandAsync(
         CommandSpec commandSpec,
         FileInfo appHostFile,
@@ -177,8 +224,16 @@ public GuestRuntime(RuntimeSpec spec, ILogger logger, FileLoggerProvider? fileLo
     {
         var args = ReplacePlaceholders(commandSpec.Args, appHostFile, directory, additionalArgs);
 
-        await EnsureMigrationFilesExistAsync(directory, cancellationToken);
+        var mergedEnvironment = MergeEnvironmentVariables(environmentVariables, commandSpec);
+
+        _logger.LogDebug("Launching: {Command} {Args}", commandSpec.Command, string.Join(" ", args));
+        return await launcher.LaunchAsync(commandSpec.Command, args, directory, mergedEnvironment, cancellationToken);
+    }
 
+    private static Dictionary<string, string> MergeEnvironmentVariables(
+        IDictionary<string, string> environmentVariables,
+        CommandSpec commandSpec)
+    {
         var mergedEnvironment = new Dictionary<string, string>(environmentVariables);
         if (commandSpec.EnvironmentVariables is not null)
         {
@@ -188,8 +243,7 @@ public GuestRuntime(RuntimeSpec spec, ILogger logger, FileLoggerProvider? fileLo
             }
         }
 
-        _logger.LogDebug("Launching: {Command} {Args}", commandSpec.Command, string.Join(" ", args));
-        return await launcher.LaunchAsync(commandSpec.Command, args, directory, mergedEnvironment, cancellationToken);
+        return mergedEnvironment;
     }
 
     /// <summary>

src/Aspire.Cli/Projects/TypeScriptAppHostToolchainResolver.cs

@@ -144,6 +144,7 @@ public static RuntimeSpec ApplyToRuntimeSpec(RuntimeSpec baseRuntimeSpec, TypeSc
             DetectionPatterns = baseRuntimeSpec.DetectionPatterns,
             Initialize = baseRuntimeSpec.Initialize,
             InstallDependencies = CreateInstallCommand(toolchain),
+            PreExecute = CreatePreExecuteCommands(toolchain, tsConfigFileName),
             Execute = CreateExecuteCommand(toolchain, tsConfigFileName),
             WatchExecute = CreateWatchCommand(toolchain, tsConfigFileName),
             PublishExecute = baseRuntimeSpec.PublishExecute,
@@ -161,6 +162,32 @@ private static CommandSpec CreateInstallCommand(TypeScriptAppHostToolchain toolc
         };
     }
 
+    private static CommandSpec[] CreatePreExecuteCommands(TypeScriptAppHostToolchain toolchain, string tsConfigFileName)
+    {
+        return
+        [
+            toolchain switch
+            {
+                TypeScriptAppHostToolchain.Bun => new CommandSpec
+                {
+                    Command = "bun",
+                    Args = ["run", "tsc", "--noEmit", "-p", tsConfigFileName]
+                },
+                TypeScriptAppHostToolchain.Yarn => new CommandSpec
+                {
+                    Command = "yarn",
+                    Args = ["run", "tsc", "--noEmit", "-p", tsConfigFileName]
+                },
+                TypeScriptAppHostToolchain.Pnpm => new CommandSpec
+                {
+                    Command = "pnpm",
+                    Args = ["exec", "tsc", "--noEmit", "-p", tsConfigFileName]
+                },
+                _ => throw new ArgumentOutOfRangeException(nameof(toolchain), toolchain, null)
+            }
+        ];
+    }
+
     private static CommandSpec CreateExecuteCommand(TypeScriptAppHostToolchain toolchain, string tsConfigFileName)
     {
         return toolchain switch
@@ -170,11 +197,11 @@ private static CommandSpec CreateExecuteCommand(TypeScriptAppHostToolchain toolc
                 Command = "bun",
                 Args = ["run", "{appHostFile}"]
             },
-            TypeScriptAppHostToolchain.Yarn => new CommandSpec
-            {
-                Command = "yarn",
-                Args = ["exec", "tsx", "--tsconfig", tsConfigFileName, "{appHostFile}"]
-            },
+                TypeScriptAppHostToolchain.Yarn => new CommandSpec
+                {
+                    Command = "yarn",
+                    Args = ["run", "tsx", "--tsconfig", tsConfigFileName, "{appHostFile}"]
+                },
             TypeScriptAppHostToolchain.Pnpm => new CommandSpec
             {
                 Command = "pnpm",
@@ -191,7 +218,17 @@ private static CommandSpec CreateWatchCommand(TypeScriptAppHostToolchain toolcha
             TypeScriptAppHostToolchain.Bun => new CommandSpec
             {
                 Command = "bun",
-                Args = ["--watch", "run", "{appHostFile}"]
+                Args =
+                [
+                    "run",
+                    "nodemon",
+                    "--signal", "SIGTERM",
+                    "--watch", ".",
+                    "--ext", "ts",
+                    "--ignore", "node_modules/",
+                    "--ignore", ".modules/",
+                    "--exec", $"bun run tsc --noEmit -p {tsConfigFileName} && bun run \"{{appHostFile}}\""
+                ]
             },
             TypeScriptAppHostToolchain.Yarn => new CommandSpec
             {
@@ -205,7 +242,7 @@ private static CommandSpec CreateWatchCommand(TypeScriptAppHostToolchain toolcha
                     "--ext", "ts",
                     "--ignore", "node_modules/",
                     "--ignore", ".modules/",
-                    "--exec", $"yarn exec tsx --tsconfig {tsConfigFileName} {{appHostFile}}"
+                    "--exec", $"yarn run tsc --noEmit -p {tsConfigFileName} && yarn run tsx --tsconfig {tsConfigFileName} \"{{appHostFile}}\""
                 ]
             },
             TypeScriptAppHostToolchain.Pnpm => new CommandSpec
@@ -220,7 +257,7 @@ private static CommandSpec CreateWatchCommand(TypeScriptAppHostToolchain toolcha
                     "--ext", "ts",
                     "--ignore", "node_modules/",
                     "--ignore", ".modules/",
-                    "--exec", $"pnpm exec tsx --tsconfig {tsConfigFileName} {{appHostFile}}"
+                    "--exec", $"pnpm exec tsc --noEmit -p {tsConfigFileName} && pnpm exec tsx --tsconfig {tsConfigFileName} \"{{appHostFile}}\""
                 ]
             },
             _ => throw new ArgumentOutOfRangeException(nameof(toolchain), toolchain, null)

src/Aspire.Hosting.CodeGeneration.TypeScript/TypeScriptLanguageSupport.cs

@@ -266,6 +266,14 @@ public RuntimeSpec GetRuntimeSpec()
                 Command = "npm",
                 Args = ["install"]
             },
+            PreExecute =
+            [
+                new CommandSpec
+                {
+                    Command = "npx",
+                    Args = ["--no-install", "tsc", "--noEmit", "-p", AppHostTsConfigFileName]
+                }
+            ],
             Execute = new CommandSpec
             {
                 Command = "npx",
@@ -282,7 +290,7 @@ public RuntimeSpec GetRuntimeSpec()
                     "--ext", "ts",
                     "--ignore", "node_modules/",
                     "--ignore", ".modules/",
-                    "--exec", $"npx --no-install tsx --tsconfig {AppHostTsConfigFileName} {{appHostFile}}"
+                    "--exec", $"npx --no-install tsc --noEmit -p {AppHostTsConfigFileName} && npx --no-install tsx --tsconfig {AppHostTsConfigFileName} \"{{appHostFile}}\""
                 ]
             },
             MigrationFiles = new Dictionary<string, string>

src/Aspire.TypeSystem/RuntimeSpec.cs

@@ -39,6 +39,12 @@ public sealed class RuntimeSpec
     /// </summary>
     public CommandSpec? InstallDependencies { get; init; }
 
+    /// <summary>
+    /// Gets the commands to run before executing or publishing the AppHost. Null if no pre-execution validation is needed.
+    /// Watch-mode validation should be part of <see cref="WatchExecute" /> when needed.
+    /// </summary>
+    public CommandSpec[]? PreExecute { get; init; }
+
     /// <summary>
     /// Gets the command to execute the AppHost for run.
     /// </summary>

tests/Aspire.Cli.EndToEnd.Tests/KubernetesDeployTypeScriptTests.cs

@@ -96,9 +96,11 @@ public async Task DeployTypeScriptAppToKubernetes()
 
 // Add Kubernetes environment with Helm deployment
 const k8sEnv = await builder.addKubernetesEnvironment("env");
-await k8sEnv.withHelm(async (helm) => {
-    await helm.withNamespace(k8sNamespace);
-    await helm.withChartVersion(chartVersion);
+await k8sEnv.withHelm({
+    configure: async (helm) => {
+        await helm.withNamespace(k8sNamespace);
+        await helm.withChartVersion(chartVersion);
+    },
 });
 
 await builder.build().run();

tests/Aspire.Cli.EndToEnd.Tests/TypeScriptPublishTests.cs

@@ -240,7 +240,7 @@ public async Task PublishWithConfigureEnvFileUpdatesEnvOutput()
             const builder = await createBuilder();
 
             const compose = await builder.addDockerComposeEnvironment("compose");
-            await compose.withDashboard(false);
+            await compose.withDashboard({ enabled: false });
 
             const container = await builder.addContainer("my-container", "nginx:alpine");
             await container.withBindMount("/host/path/data", "/container/data");

tests/Aspire.Cli.Tests/Projects/GuestRuntimeTests.cs

@@ -28,7 +28,8 @@ private static RuntimeSpec CreateTestSpec(
         CommandSpec? execute = null,
         CommandSpec? watchExecute = null,
         CommandSpec? publishExecute = null,
-        CommandSpec? installDependencies = null)
+        CommandSpec? installDependencies = null,
+        CommandSpec[]? preExecute = null)
     {
         return new RuntimeSpec
         {
@@ -43,7 +44,8 @@ private static RuntimeSpec CreateTestSpec(
             },
             WatchExecute = watchExecute,
             PublishExecute = publishExecute,
-            InstallDependencies = installDependencies
+            InstallDependencies = installDependencies,
+            PreExecute = preExecute
         };
     }
 
@@ -111,6 +113,72 @@ public async Task RunAsync_WatchMode_UsesWatchExecuteSpec()
         Assert.Contains("--watch", launcher.LastArgs);
     }
 
+    [Fact]
+    public async Task RunAsync_WatchModeWithWatchExecute_SkipsPreExecute()
+    {
+        var spec = CreateTestSpec(
+            execute: new CommandSpec { Command = "run-cmd", Args = ["{appHostFile}"] },
+            watchExecute: new CommandSpec { Command = "watch-cmd", Args = ["--watch", "{appHostFile}"] },
+            preExecute:
+            [
+                new CommandSpec { Command = "typecheck-cmd", Args = ["--noEmit"] }
+            ]);
+        var runtime = CreateRuntime(spec);
+        var launcher = new RecordingLauncher();
+        var appHostFile = new FileInfo("/tmp/apphost.ts");
+        var directory = new DirectoryInfo("/tmp");
+
+        var (exitCode, _) = await runtime.RunAsync(appHostFile, directory, new Dictionary<string, string>(), watchMode: true, launcher, CancellationToken.None);
+
+        Assert.Equal(0, exitCode);
+        var call = Assert.Single(launcher.Calls);
+        Assert.Equal("watch-cmd", call.Command);
+    }
+
+    [Fact]
+    public async Task RunAsync_RunsPreExecuteBeforeExecute()
+    {
+        var spec = CreateTestSpec(
+            execute: new CommandSpec { Command = "run-cmd", Args = ["{appHostFile}"] },
+            preExecute:
+            [
+                new CommandSpec { Command = "typecheck-cmd", Args = ["--project", "{appHostDir}"] }
+            ]);
+        var runtime = CreateRuntime(spec);
+        var launcher = new RecordingLauncher();
+        var appHostFile = new FileInfo("/tmp/apphost.ts");
+        var directory = new DirectoryInfo("/tmp");
+
+        await runtime.RunAsync(appHostFile, directory, new Dictionary<string, string>(), watchMode: false, launcher, CancellationToken.None);
+
+        Assert.Equal(2, launcher.Calls.Count);
+        Assert.Equal("typecheck-cmd", launcher.Calls[0].Command);
+        Assert.Equal(["--project", directory.FullName], launcher.Calls[0].Args);
+        Assert.Equal("run-cmd", launcher.Calls[1].Command);
+    }
+
+    [Fact]
+    public async Task RunAsync_WhenPreExecuteFails_DoesNotExecute()
+    {
+        var spec = CreateTestSpec(
+            execute: new CommandSpec { Command = "run-cmd", Args = ["{appHostFile}"] },
+            preExecute:
+            [
+                new CommandSpec { Command = "typecheck-cmd", Args = ["--noEmit"] }
+            ]);
+        var runtime = CreateRuntime(spec);
+        var launcher = new RecordingLauncher();
+        launcher.ExitCodes.Enqueue(2);
+        var appHostFile = new FileInfo("/tmp/apphost.ts");
+        var directory = new DirectoryInfo("/tmp");
+
+        var (exitCode, _) = await runtime.RunAsync(appHostFile, directory, new Dictionary<string, string>(), watchMode: false, launcher, CancellationToken.None);
+
+        Assert.Equal(2, exitCode);
+        var call = Assert.Single(launcher.Calls);
+        Assert.Equal("typecheck-cmd", call.Command);
+    }
+
     [Fact]
     public async Task RunAsync_WatchModeWithoutWatchSpec_FallsBackToExecute()
     {
@@ -143,6 +211,28 @@ public async Task PublishAsync_UsesPublishExecuteSpec()
         Assert.Contains(launcher.LastArgs, a => a.Contains("--output") && a.Contains("/out"));
     }
 
+    [Fact]
+    public async Task PublishAsync_RunsPreExecuteBeforePublishExecute()
+    {
+        var spec = CreateTestSpec(
+            execute: new CommandSpec { Command = "run-cmd", Args = ["{appHostFile}"] },
+            publishExecute: new CommandSpec { Command = "publish-cmd", Args = ["{appHostFile}", "{args}"] },
+            preExecute:
+            [
+                new CommandSpec { Command = "typecheck-cmd", Args = ["--project", "{appHostDir}"] }
+            ]);
+        var runtime = CreateRuntime(spec);
+        var launcher = new RecordingLauncher();
+        var appHostFile = new FileInfo("/tmp/apphost.ts");
+        var directory = new DirectoryInfo("/tmp");
+
+        await runtime.PublishAsync(appHostFile, directory, new Dictionary<string, string>(), ["--output", "/out"], launcher, CancellationToken.None);
+
+        Assert.Equal(2, launcher.Calls.Count);
+        Assert.Equal("typecheck-cmd", launcher.Calls[0].Command);
+        Assert.Equal("publish-cmd", launcher.Calls[1].Command);
+    }
+
     [Fact]
     public async Task PublishAsync_WithoutPublishSpec_FallsBackToExecute()
     {
@@ -527,6 +617,8 @@ public async Task RunAsync_NoMigrationFiles_ExecutesNormally()
 
     private sealed class RecordingLauncher : IGuestProcessLauncher
     {
+        public List<(string Command, string[] Args)> Calls { get; } = [];
+        public Queue<int> ExitCodes { get; } = [];
         public string LastCommand { get; private set; } = string.Empty;
         public string[] LastArgs { get; private set; } = [];
         public DirectoryInfo? LastWorkingDirectory { get; private set; }
@@ -539,11 +631,13 @@ private sealed class RecordingLauncher : IGuestProcessLauncher
             IDictionary<string, string> environmentVariables,
             CancellationToken cancellationToken)
         {
+            Calls.Add((command, args));
             LastCommand = command;
             LastArgs = args;
             LastWorkingDirectory = workingDirectory;
             LastEnvironmentVariables = new Dictionary<string, string>(environmentVariables);
-            return Task.FromResult<(int, OutputCollector?)>((0, new OutputCollector()));
+            var exitCode = ExitCodes.Count > 0 ? ExitCodes.Dequeue() : 0;
+            return Task.FromResult<(int, OutputCollector?)>((exitCode, new OutputCollector()));
         }
     }
 }