Add WithGoModTidy and WithGoModDownload for Golang integration

src/CommunityToolkit.Aspire.Hosting.Golang/GoModInstallerResource.cs

@@ -0,0 +1,9 @@
+namespace Aspire.Hosting.ApplicationModel;
+
+/// <summary>
+/// A resource that represents a Go module installer that runs go mod tidy or go mod download.
+/// </summary>
+/// <param name="name">The name of the resource.</param>
+/// <param name="workingDirectory">The working directory to use for the command.</param>
+public class GoModInstallerResource(string name, string workingDirectory)
+    : ExecutableResource(name, "go", workingDirectory);

src/CommunityToolkit.Aspire.Hosting.Golang/GolangAppHostingExtension.cs

@@ -234,4 +234,68 @@ private static string GetDefaultGoBaseImage(string workingDirectory, IServicePro
         logger.LogDebug("No Go version detected, will use default version");
         return null;
     }
+
+    /// <summary>
+    /// Ensures Go module dependencies are tidied before the application starts using <c>go mod tidy</c>.
+    /// </summary>
+    /// <param name="builder">The Golang app resource builder.</param>
+    /// <param name="configureInstaller">Optional action to configure the installer resource.</param>
+    /// <returns>A reference to the <see cref="IResourceBuilder{T}"/>.</returns>
+    public static IResourceBuilder<GolangAppExecutableResource> WithGoModTidy(
+        this IResourceBuilder<GolangAppExecutableResource> builder,
+        Action<IResourceBuilder<GoModInstallerResource>>? configureInstaller = null)
+    {
+        ArgumentNullException.ThrowIfNull(builder, nameof(builder));
+
+        // Only install packages during development, not in publish mode
+        if (!builder.ApplicationBuilder.ExecutionContext.IsPublishMode)
+        {
+            var installerName = $"{builder.Resource.Name}-go-mod-tidy";
+            var installer = new GoModInstallerResource(installerName, builder.Resource.WorkingDirectory);
+
+            var installerBuilder = builder.ApplicationBuilder.AddResource(installer)
+                .WithArgs("mod", "tidy")
+                .WithParentRelationship(builder.Resource)
+                .ExcludeFromManifest();
+
+            // Make the parent resource wait for the installer to complete
+            builder.WaitForCompletion(installerBuilder);
+
+            configureInstaller?.Invoke(installerBuilder);
+        }
+
+        return builder;
+    }
+
+    /// <summary>
+    /// Ensures Go module dependencies are downloaded before the application starts using <c>go mod download</c>.
+    /// </summary>
+    /// <param name="builder">The Golang app resource builder.</param>
+    /// <param name="configureInstaller">Optional action to configure the installer resource.</param>
+    /// <returns>A reference to the <see cref="IResourceBuilder{T}"/>.</returns>
+    public static IResourceBuilder<GolangAppExecutableResource> WithGoModDownload(
+        this IResourceBuilder<GolangAppExecutableResource> builder,
+        Action<IResourceBuilder<GoModInstallerResource>>? configureInstaller = null)
+    {
+        ArgumentNullException.ThrowIfNull(builder, nameof(builder));
+
+        // Only install packages during development, not in publish mode
+        if (!builder.ApplicationBuilder.ExecutionContext.IsPublishMode)
+        {
+            var installerName = $"{builder.Resource.Name}-go-mod-download";
+            var installer = new GoModInstallerResource(installerName, builder.Resource.WorkingDirectory);
+
+            var installerBuilder = builder.ApplicationBuilder.AddResource(installer)
+                .WithArgs("mod", "download")
+                .WithParentRelationship(builder.Resource)
+                .ExcludeFromManifest();
+
+            // Make the parent resource wait for the installer to complete
+            builder.WaitForCompletion(installerBuilder);
+
+            configureInstaller?.Invoke(installerBuilder);
+        }
+
+        return builder;
+    }
 }

src/CommunityToolkit.Aspire.Hosting.Golang/README.md

@@ -29,6 +29,45 @@ To have the Golang application listen on the correct port, you can use the follo
 r.Run(":"+os.Getenv("PORT"))
 ```
 
+## Dependency Management
+
+The integration provides support for Go module dependency management using `go mod tidy` or `go mod download`.
+
+### Using `go mod tidy`
+
+To run `go mod tidy` before your application starts (to clean up and verify dependencies):
+
+```csharp
+var golang = builder.AddGolangApp("golang", "../gin-api")
+    .WithGoModTidy()
+    .WithHttpEndpoint(env: "PORT");
+```
+
+### Using `go mod download`
+
+To run `go mod download` before your application starts (to download dependencies without verification):
+
+```csharp
+var golang = builder.AddGolangApp("golang", "../gin-api")
+    .WithGoModDownload()
+    .WithHttpEndpoint(env: "PORT");
+```
+
+Both methods create an installer resource that runs before your application starts, ensuring dependencies are available. The installer resource appears as a child resource in the Aspire dashboard.
+
+You can also customize the installer resource using the optional `configureInstaller` parameter:
+
+```csharp
+var golang = builder.AddGolangApp("golang", "../gin-api")
+    .WithGoModTidy(configureInstaller: installer =>
+    {
+        installer.WithEnvironment("GOPROXY", "https://proxy.golang.org,direct");
+    })
+    .WithHttpEndpoint(env: "PORT");
+```
+
+> **Note:** The `WithGoModTidy` and `WithGoModDownload` methods only run during development. When publishing, the generated Dockerfile handles dependency management automatically.
+
 ## Publishing
 
 When publishing your Aspire application, the Golang resource automatically generates a multi-stage Dockerfile for containerization. This means you don't need to manually create a Dockerfile for your Golang application.

tests/CommunityToolkit.Aspire.Hosting.Golang.Tests/ResourceCreationTests.cs

@@ -88,4 +88,98 @@ public async Task GolangAppWithExecutableAsync()
             }
         );
     }
+
+    [Fact]
+    public void GolangAppWithGoModTidyCreatesInstallerResource()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        builder.AddGolangApp("golang", "../../examples/golang/gin-api").WithGoModTidy();
+
+        using var app = builder.Build();
+
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var golangResource = Assert.Single(appModel.Resources.OfType<GolangAppExecutableResource>());
+        var installerResource = Assert.Single(appModel.Resources.OfType<GoModInstallerResource>());
+
+        Assert.Equal("golang-go-mod-tidy", installerResource.Name);
+        Assert.Equal("go", installerResource.Command);
+    }
+
+    [Fact]
+    public async Task GolangAppWithGoModTidyHasCorrectArgsAsync()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        builder.AddGolangApp("golang", "../../examples/golang/gin-api").WithGoModTidy();
+
+        using var app = builder.Build();
+
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var installerResource = Assert.Single(appModel.Resources.OfType<GoModInstallerResource>());
+
+        var args = await installerResource.GetArgumentValuesAsync();
+        Assert.Collection(
+            args,
+            arg => Assert.Equal("mod", arg),
+            arg => Assert.Equal("tidy", arg)
+        );
+    }
+
+    [Fact]
+    public void GolangAppWithGoModDownloadCreatesInstallerResource()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        builder.AddGolangApp("golang", "../../examples/golang/gin-api").WithGoModDownload();
+
+        using var app = builder.Build();
+
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var golangResource = Assert.Single(appModel.Resources.OfType<GolangAppExecutableResource>());
+        var installerResource = Assert.Single(appModel.Resources.OfType<GoModInstallerResource>());
+
+        Assert.Equal("golang-go-mod-download", installerResource.Name);
+        Assert.Equal("go", installerResource.Command);
+    }
+
+    [Fact]
+    public async Task GolangAppWithGoModDownloadHasCorrectArgsAsync()
+    {
+        var builder = DistributedApplication.CreateBuilder();
+
+        builder.AddGolangApp("golang", "../../examples/golang/gin-api").WithGoModDownload();
+
+        using var app = builder.Build();
+
+        var appModel = app.Services.GetRequiredService<DistributedApplicationModel>();
+
+        var installerResource = Assert.Single(appModel.Resources.OfType<GoModInstallerResource>());
+
+        var args = await installerResource.GetArgumentValuesAsync();
+        Assert.Collection(
+            args,
+            arg => Assert.Equal("mod", arg),
+            arg => Assert.Equal("download", arg)
+        );
+    }
+
+    [Fact]
+    public void WithGoModTidyNullBuilderThrows()
+    {
+        IResourceBuilder<GolangAppExecutableResource> builder = null!;
+
+        Assert.Throws<ArgumentNullException>(() => builder.WithGoModTidy());
+    }
+
+    [Fact]
+    public void WithGoModDownloadNullBuilderThrows()
+    {
+        IResourceBuilder<GolangAppExecutableResource> builder = null!;
+
+        Assert.Throws<ArgumentNullException>(() => builder.WithGoModDownload());
+    }
 }