[release/13.3] Stop forcing MSBuild server for Aspire CLI builds

src/Aspire.Cli/DotNet/DotNetCliRunner.cs

@@ -77,11 +77,6 @@ internal sealed class DotNetCliRunner(
     private const int MaxSearchRetries = 3;
     private static readonly TimeSpan[] s_searchRetryDelays = [TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(2)];
 
-    private string GetMsBuildServerValue()
-    {
-        return configuration["DOTNET_CLI_USE_MSBUILD_SERVER"] ?? "true";
-    }
-
     internal static string GetBackchannelSocketPath()
     {
         return CliPathHelper.CreateUnixDomainSocketPath("cli.sock");
@@ -520,12 +515,6 @@ public async Task<int> RunAsync(FileInfo projectFile, bool watch, bool noBuild,
         // We copy the dictionary here because we don't want to mutate the input.
         var finalEnv = env?.ToDictionary() ?? new Dictionary<string, string>();
 
-        // Inject DOTNET_CLI_USE_MSBUILD_SERVER when noBuild == false
-        if (!noBuild)
-        {
-            finalEnv["DOTNET_CLI_USE_MSBUILD_SERVER"] = GetMsBuildServerValue();
-        }
-
         // Check if update notifications are disabled and set version check environment variable
         if (!features.IsFeatureEnabled(KnownFeatures.UpdateNotificationsEnabled, defaultValue: true))
         {
@@ -808,15 +797,9 @@ public async Task<int> BuildAsync(FileInfo projectFilePath, bool noRestore, Proc
         string[] cliArgs = ["build", noRestoreSwitch, projectFilePath.FullName];
         cliArgs = [.. cliArgs.Where(arg => !string.IsNullOrWhiteSpace(arg))];
 
-        // Always inject DOTNET_CLI_USE_MSBUILD_SERVER for apphost builds
-        var env = new Dictionary<string, string>
-        {
-            ["DOTNET_CLI_USE_MSBUILD_SERVER"] = GetMsBuildServerValue()
-        };
-
         return await ExecuteAsync(
             args: cliArgs,
-            env: env,
+            env: null,
             projectFile: projectFilePath,
             workingDirectory: projectFilePath.Directory!,
             backchannelCompletionSource: null,

tests/Aspire.Cli.Tests/DotNet/DotNetCliRunnerTests.cs

@@ -66,7 +66,7 @@ public async Task DotNetCliCorrectlyAppliesNoLaunchProfileArgumentWhenSpecifiedI
     }
 
     [Fact]
-    public async Task BuildAsyncAlwaysInjectsDotnetCliUseMsBuildServerEnvironmentVariable()
+    public async Task BuildAsyncDoesNotInjectDotnetCliUseMsBuildServerEnvironmentVariable()
     {
         using var workspace = TemporaryWorkspace.Create(outputHelper);
         var projectFile = new FileInfo(Path.Combine(workspace.WorkspaceRoot.FullName, "AppHost.csproj"));
@@ -84,8 +84,7 @@ public async Task BuildAsyncAlwaysInjectsDotnetCliUseMsBuildServerEnvironmentVar
             (args, env, _, _) =>
             {
                 Assert.NotNull(env);
-                Assert.True(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
-                Assert.Equal("true", env["DOTNET_CLI_USE_MSBUILD_SERVER"]);
+                Assert.False(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
             },
             0);
 
@@ -123,14 +122,13 @@ public async Task RestoreAsyncRunsDotnetRestoreCommand()
     }
 
     [Fact]
-    public async Task BuildAsyncUsesConfigurationValueForDotnetCliUseMsBuildServer()
+    public async Task BuildAsyncDoesNotInjectConfiguredDotnetCliUseMsBuildServer()
     {
         using var workspace = TemporaryWorkspace.Create(outputHelper);
         var projectFile = new FileInfo(Path.Combine(workspace.WorkspaceRoot.FullName, "AppHost.csproj"));
         await File.WriteAllTextAsync(projectFile.FullName, "Not a real project file.");
 
         var services = CliTestHelper.CreateServiceCollection(workspace, outputHelper);
-        // Add a configuration value that overrides the default
         services.AddSingleton<IConfiguration>(sp =>
         {
             var configBuilder = new ConfigurationBuilder();
@@ -151,8 +149,7 @@ public async Task BuildAsyncUsesConfigurationValueForDotnetCliUseMsBuildServer()
             (args, env, _, _) =>
             {
                 Assert.NotNull(env);
-                Assert.True(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
-                Assert.Equal("false", env["DOTNET_CLI_USE_MSBUILD_SERVER"]);
+                Assert.False(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
             },
             0);
 
@@ -220,7 +217,7 @@ public async Task BuildAsyncDoesNotIncludeNoRestoreFlagWhenNoRestoreIsFalse()
     }
 
     [Fact]
-    public async Task RunAsyncInjectsDotnetCliUseMsBuildServerWhenNoBuildIsFalse()
+    public async Task RunAsyncDoesNotInjectDotnetCliUseMsBuildServerWhenNoBuildIsFalse()
     {
         using var workspace = TemporaryWorkspace.Create(outputHelper);
         var projectFile = new FileInfo(Path.Combine(workspace.WorkspaceRoot.FullName, "AppHost.csproj"));
@@ -238,15 +235,14 @@ public async Task RunAsyncInjectsDotnetCliUseMsBuildServerWhenNoBuildIsFalse()
             (args, env, _, _) =>
             {
                 Assert.NotNull(env);
-                Assert.True(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
-                Assert.Equal("true", env["DOTNET_CLI_USE_MSBUILD_SERVER"]);
+                Assert.False(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
             },
             0);
 
         var exitCode = await runner.RunAsync(
             projectFile: projectFile,
             watch: false,
-            noBuild: false, // This should inject the environment variable
+            noBuild: false,
             noRestore: false,
             args: ["--operation", "inspect"],
             env: new Dictionary<string, string>(),
@@ -317,8 +313,7 @@ public async Task RunAsyncPreservesExistingEnvironmentVariables()
             (args, env, _, _) =>
             {
                 Assert.NotNull(env);
-                Assert.True(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
-                Assert.Equal("true", env["DOTNET_CLI_USE_MSBUILD_SERVER"]);
+                Assert.False(env.ContainsKey("DOTNET_CLI_USE_MSBUILD_SERVER"));
                 // Verify existing environment variable is preserved
                 Assert.True(env.ContainsKey("EXISTING_VAR"));
                 Assert.Equal("existing_value", env["EXISTING_VAR"]);