# GoHostingExtensions Methods

- Package: [Aspire.Hosting.Go](/reference/api/csharp/aspire.hosting.go.md)
- Type: [GoHostingExtensions](/reference/api/csharp/aspire.hosting.go/gohostingextensions.md)
- Kind: `Methods`
- Members: `8`

Provides extension methods for adding Go applications to an `Hosting.IDistributedApplicationBuilder`.

## AddGoApp(IDistributedApplicationBuilder, string, string, string, string[]?, string?, string?, bool)

- Name: `AddGoApp(IDistributedApplicationBuilder, string, string, string, string[]?, string?, string?, bool)`
- Modifiers: `extension`
- Returns: `IResourceBuilder<GoAppResource>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L82-L327)

Adds a Go application to the application model. The Go toolchain must be available on the PATH.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<GoAppResource> AddGoApp(
        this IDistributedApplicationBuilder builder,
        string name,
        string appDirectory,
        string packagePath = ".",
        string[]? buildTags = null,
        string? ldFlags = null,
        string? gcFlags = null,
        bool raceDetector = false)
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IDistributedApplicationBuilder`)
  The `Hosting.IDistributedApplicationBuilder` to add the resource to.
- `name` (`string`)
  The name of the resource.
- `appDirectory` (`string`)
  The path to the directory that acts as both the Go module root (where `go.mod` lives) and the Docker build context for `aspire publish`.
- `packagePath` (`string`) `optional`
  The Go package to run or build, relative to `appDirectory`. Defaults to `"."` (the module root itself). Use a sub-path such as `"./cmd/server"` when the main package is not at the module root (e.g. `api/cmd/server/main.go` with `api/go.mod`). This value is passed to `go run`, `dlv debug`, and `go build` consistently.
- `buildTags` (`string[]?`) `optional`
  Optional build tags passed to the compiler via `-tags` (e.g. `"netgo"`, `"integration"`).
- `ldFlags` (`string?`) `optional`
  Optional linker flags passed via `-ldflags` (e.g. `"-X main.version=1.0.0"`).
- `gcFlags` (`string?`) `optional`
  Optional compiler flags passed via `-gcflags` (e.g. `"all=-N -l"` to disable optimisations for Delve).
- `raceDetector` (`bool`) `optional`
  When `true`, enables the Go race detector by passing `-race` to `go run`.

## Returns

`IResourceBuilder<GoAppResource>` -- A reference to the `ApplicationModel.IResourceBuilder`1`.

## Remarks

This method executes the Go application using `go run .`. The Go toolchain resolves the entry point from the package in `appDirectory`.

Go applications automatically have VS Code debugging support enabled via Delve. Use [GoHostingExtensions.WithModTidy(IResourceBuilder<T>)](/reference/api/csharp/aspire.hosting.go/gohostingextensions/methods.md#withmodtidy-iresourcebuilder-t), [GoHostingExtensions.WithModVendor(IResourceBuilder<T>)](/reference/api/csharp/aspire.hosting.go/gohostingextensions/methods.md#withmodvendor-iresourcebuilder-t), or [GoHostingExtensions.WithModDownload(IResourceBuilder<T>)](/reference/api/csharp/aspire.hosting.go/gohostingextensions/methods.md#withmoddownload-iresourcebuilder-t) to manage module dependencies before startup, and [GoHostingExtensions.WithVetTool(IResourceBuilder<T>)](/reference/api/csharp/aspire.hosting.go/gohostingextensions/methods.md#withvettool-iresourcebuilder-t) to run static analysis. Use [GoHostingExtensions.WithAppArgs(IResourceBuilder<T>, object[])](/reference/api/csharp/aspire.hosting.go/gohostingextensions/methods.md#withappargs-iresourcebuilder-t-object) to pass runtime program arguments, and [GoHostingExtensions.WithDelveServer(IResourceBuilder<T>, int)](/reference/api/csharp/aspire.hosting.go/gohostingextensions/methods.md#withdelveserver-iresourcebuilder-t-int) to enable remote debugging via a headless Delve server.

## Examples

Add a Go API to the application model with build tags and linker flags:

```csharp
var builder = DistributedApplication.CreateBuilder(args);

builder.AddGoApp("api", "../go-api",
           buildTags: ["netgo"],
           ldFlags: "-X main.version=1.0.0")
       .WithHttpEndpoint(port: 8080)
       .WithExternalHttpEndpoints();

builder.Build().Run();
```

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.

## WithAppArgs(IResourceBuilder<T>, object[])

- Name: `WithAppArgs(IResourceBuilder<T>, object[])`
- Modifiers: `extension`
- Returns: `IResourceBuilder<T>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L343-L345)

Passes extra arguments to the Go program at runtime. In normal run mode they appear after `go run .`; in Delve mode after the `--` separator.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<T> WithAppArgs<T>(
        this IResourceBuilder<T> builder,
        params object[] args)
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IResourceBuilder<T>`)
  The resource builder for the Go application.
- `args` (`object[]`)
  The program arguments (e.g., `"serve"`, `"--config"`, `"prod.yaml"`).

## Returns

`IResourceBuilder<T>` -- A reference to the `ApplicationModel.IResourceBuilder`1` for chaining.

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.

## WithDelveServer(IResourceBuilder<T>, int)

- Name: `WithDelveServer(IResourceBuilder<T>, int)`
- Modifiers: `extension`
- Returns: `IResourceBuilder<T>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L644-L662)

Starts a headless Delve debug server so that any DAP-compatible client can attach remotely. The application is launched as `dlv --headless=true --listen=127.0.0.1:<port> --api-version=2 debug .` instead of `go run .`. Delve must be available on the PATH.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<T> WithDelveServer<T>(
        this IResourceBuilder<T> builder,
        int port = 2345)
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IResourceBuilder<T>`)
  The resource builder for the Go application.
- `port` (`int`) `optional`
  The TCP port Delve listens on. Defaults to `2345`.

## Returns

`IResourceBuilder<T>` -- A reference to the `ApplicationModel.IResourceBuilder`1` for chaining.

## Remarks

Delve is the only Go debugger; both GoLand and VS Code use it under the hood, just in different modes:

- **GoLand** -- Create a Go Remote run configuration pointing at `localhost:<port>` and start it after the resource has started.
- **VS Code (attach mode)** -- Add a `"request": "attach"` entry to `launch.json` with `"mode": "remote"`, `"host": "localhost"`, and `"port": <port>`, then start it after the resource has started.

VS Code users who do not need GoLand compatibility can rely on the automatic VS Code debugging support that [GoHostingExtensions.AddGoApp(IDistributedApplicationBuilder, string, string, string, string[]?, string?, string?, bool)](/reference/api/csharp/aspire.hosting.go/gohostingextensions/methods.md#addgoapp-idistributedapplicationbuilder-string-string-string-string-string-string-bool) enables by default -- no change to the application command is required in that case.

## Examples

```csharp
builder.AddGoApp("api", "../go-api")
       .WithDelveServer(port: 2345);
```

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.

## WithGoPrivate(IResourceBuilder<T>, string[], string, string, string)

- Name: `WithGoPrivate(IResourceBuilder<T>, string[], string, string, string)`
- Modifiers: `extension`
- Returns: `IResourceBuilder<T>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L582-L596)

Configures private Go module authentication for publish-time Dockerfile generation.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<T> WithGoPrivate<T>(
        this IResourceBuilder<T> builder,
        string[] privatePatterns,
        string authHost,
        string usernameArgName = "GIT_USER",
        string tokenSecretId = "gittoken")
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IResourceBuilder<T>`)
  The resource builder for the Go application.
- `privatePatterns` (`string[]`)
  One or more module path patterns that should bypass the public proxy and checksum database, e.g. `"*.mycompany.com"` or `"github.com/myorg"`. Passed verbatim to `GOPRIVATE`, which implicitly covers `GONOSUMCHECK` and `GONOPROXY`.
- `authHost` (`string`)
  The Git host that requires authentication, e.g. `"github.com"`.
- `usernameArgName` (`string`) `optional`
  The Docker build-arg name for the Git username. Defaults to `"GIT_USER"`. Pass it at build time with `--build-arg GIT_USER=myuser`.
- `tokenSecretId` (`string`) `optional`
  The BuildKit secret ID for the Git access token. Defaults to `"gittoken"`. Pass it at build time with `--secret id=gittoken,src=/path/to/token`.

## Returns

`IResourceBuilder<T>` -- A reference to the `ApplicationModel.IResourceBuilder`1` for chaining.

## Remarks

Only affects the generated Dockerfile -- has no effect in run mode, where the local Go toolchain picks up credentials from the developer's own `~/.netrc` or git credential helper.

The generated build stage writes a temporary `.netrc` file from the username build-arg and the token secret, runs `go mod download`, then removes the file -- all in a single layer so credentials never persist in the image.

## Examples

Build with: docker build --build-arg GIT_USER=myuser --secret id=gittoken,src=~/.git-token .

```csharp
builder.AddGoApp("api", "../go-api")
       .WithGoPrivate(["github.com/myorg"], "github.com");
```

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.

## WithModDownload(IResourceBuilder<T>)

- Name: `WithModDownload(IResourceBuilder<T>)`
- Modifiers: `extension`
- Returns: `IResourceBuilder<T>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L457-L490)

Runs `go mod download` before starting the application, pre-fetching all module dependencies into the local module cache without modifying `go.sum`. The main application waits for the download step to complete successfully before launching.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<T> WithModDownload<T>(
        this IResourceBuilder<T> builder)
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IResourceBuilder<T>`)
  The resource builder for the Go application.

## Returns

`IResourceBuilder<T>` -- A reference to the `ApplicationModel.IResourceBuilder`1` for chaining.

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.

## WithModTidy(IResourceBuilder<T>)

- Name: `WithModTidy(IResourceBuilder<T>)`
- Modifiers: `extension`
- Returns: `IResourceBuilder<T>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L360-L395)

Runs `go mod tidy` before starting the application, ensuring `go.sum` is up to date. The main application waits for the tidy step to complete successfully before launching.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<T> WithModTidy<T>(
        this IResourceBuilder<T> builder)
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IResourceBuilder<T>`)
  The resource builder for the Go application.

## Returns

`IResourceBuilder<T>` -- A reference to the `ApplicationModel.IResourceBuilder`1` for chaining.

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.

## WithModVendor(IResourceBuilder<T>)

- Name: `WithModVendor(IResourceBuilder<T>)`
- Modifiers: `extension`
- Returns: `IResourceBuilder<T>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L411-L441)

Runs `go mod vendor` before starting the application, caching all module dependencies in the local `vendor/` directory. The main application waits for the vendor step to complete successfully before launching.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<T> WithModVendor<T>(
        this IResourceBuilder<T> builder)
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IResourceBuilder<T>`)
  The resource builder for the Go application.

## Returns

`IResourceBuilder<T>` -- A reference to the `ApplicationModel.IResourceBuilder`1` for chaining.

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.

## WithVetTool(IResourceBuilder<T>)

- Name: `WithVetTool(IResourceBuilder<T>)`
- Modifiers: `extension`
- Returns: `IResourceBuilder<T>`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/becb48e2d61099e35ae336d527d3875e928d6594/src/Aspire.Hosting.Go/GoHostingExtensions.cs#L505-L527)

Runs `go vet ./...` before starting the application to catch static analysis issues. The main application waits for the vet step to complete successfully before launching.

```csharp
public static class GoHostingExtensions
{
    public static IResourceBuilder<T> WithVetTool<T>(
        this IResourceBuilder<T> builder)
    {
        // ...
    }
}
```

## Parameters

- `builder` (`IResourceBuilder<T>`)
  The resource builder for the Go application.

## Returns

`IResourceBuilder<T>` -- A reference to the `ApplicationModel.IResourceBuilder`1` for chaining.

## ATS metadata

### ATS export

- Available to Polyglot AppHosts through the Aspire Type System.