func PinGemAndBundlerVersion()

in pkg/runtime/install.go [234:284]
40 lines of code
7 McCabe index (conditional complexity)

func PinGemAndBundlerVersion(ctx *gcp.Context, version string, layer *libcnb.Layer) error {
	rubygemsVersion := "3.3.15"
	bundler1Version := "1.17.3"
	bundler2Version := "2.1.4"
	installBundler1 := false

	// Bundler 1 is only installed for older versions of Ruby
	// Older 2.x Ruby versions have been using RubyGems 3.1.2 on GAE/GCF.
	if strings.HasPrefix(version, "2.") {
		rubygemsVersion = "3.1.2"
		installBundler1 = true
	}
	// Ruby 3.0 has been using 3.2.26 on GAE/GCF
	if strings.HasPrefix(version, "3.0") {
		rubygemsVersion = "3.2.26"
		installBundler1 = true
	}

	rubyBinPath := filepath.Join(layer.Path, "bin")
	gemPath := filepath.Join(rubyBinPath, "gem")

	// Update RubyGems to a fixed version
	ctx.Logf("Installing RubyGems %s", rubygemsVersion)
	_, err := ctx.Exec(
		[]string{gemPath, "update", "--no-document", "--system", rubygemsVersion}, gcp.WithUserAttribution)
	if err != nil {
		return fmt.Errorf("updating rubygems %s, err: %v", rubygemsVersion, err)
	}

	// Remove any existing bundler versions in the Ruby installation
	command := []string{"rm", "-f",
		filepath.Join(rubyBinPath, "bundle"), filepath.Join(rubyBinPath, "bundler")}
	_, err = ctx.Exec(command, gcp.WithUserAttribution)
	if err != nil {
		return fmt.Errorf("removing out-of-box bundler: %v", err)
	}

	command = []string{gemPath, "install", "--no-document", fmt.Sprintf("bundler:%s", bundler2Version)}
	if installBundler1 {
		// Install fixed versions of Bundler1 and Bundler2 for backwards compatibility
		command = append(command, fmt.Sprintf("bundler:%s", bundler1Version))
		ctx.Logf("Installing bundler %s and %s", bundler1Version, bundler2Version)
	} else {
		ctx.Logf("Installing bundler %s ", bundler2Version)
	}
	_, err = ctx.Exec(command, gcp.WithUserAttribution)
	if err != nil {
		return fmt.Errorf("installing bundler %s and %s: %v", bundler1Version, bundler2Version, err)
	}
	return nil
}