Function downloadGoModFile

internal/cli/build.go:213–251

downloadGoModFile run go mod commands to download dependencies

(b *buildingMaterial)

// downloadGoModFile run go mod commands to download dependencies
func downloadGoModFile(b *buildingMaterial) (err error) {
	answerReplacement := b.answerModuleReplacement

	// If no replacement specified and current binary is v2+, auto-determine replacement.
	// This is needed because go mod tidy would otherwise resolve github.com/apache/answer
	// to the latest v1.x version, causing v2+ features (e.g. AI/MCP) to disappear.
	if len(answerReplacement) == 0 && b.originalAnswerInfo.Version != "" {
		ver, verErr := semver.NewVersion(strings.TrimPrefix(b.originalAnswerInfo.Version, "v"))
		if verErr == nil && ver.Major() >= 2 {
			answerReplacement = fmt.Sprintf("github.com/apache/answer@%s", b.originalAnswerInfo.Version)
		}
	}

	if len(answerReplacement) > 0 {
		// For v2+ versioned module paths (e.g. github.com/apache/answer@v2.0.0),
		// go mod tidy rejects the version because the module path lacks a /v2 suffix.
		// Work around this by cloning the repo locally and using a local path replacement.
		localPath, resolveErr := resolveAnswerModuleReplacement(answerReplacement, b.tmpDir)
		if resolveErr != nil {
			return resolveErr
		}
		replacement := fmt.Sprintf("%s=%s", "github.com/apache/answer", localPath)
		err = b.newExecCmd("go", "mod", "edit", "-replace", replacement).Run()
		if err != nil {
			return err
		}
	}

	err = b.newExecCmd("go", "mod", "tidy").Run()
	if err != nil {
		return err
	}

	err = b.newExecCmd("go", "mod", "vendor").Run()
	if err != nil {
		return err
	}
	return
}

// resolveAnswerModuleReplacement resolves the ANSWER_MODULE value to a usable local path or
// remote replacement string. For v2+ versioned module paths (e.g. github.com/apache/answer@v2.0.0),