Function hypervGetSwitch

src/cmd/linuxkit/run_hyperv.go:233–266

Find a Hyper-V switch. Either check that the supplied switch exists or find the first external switch.

(name string)

// Find a Hyper-V switch. Either check that the supplied switch exists
// or find the first external switch.
func hypervGetSwitch(name string) (string, error) {
	if name != "" {
		if _, _, err := poshCmd("Get-VMSwitch", name); err != nil {
			return "", fmt.Errorf("could not find switch %s: %v", name, err)
		}
		return name, nil
	}

	// The Windows 10 Fall Creators Update adds a new 'Default
	// Switch'. Check if it is present and if so, use it.
	name = "Default Switch"
	if _, _, err := poshCmd("Get-VMSwitch", name); err == nil {
		return name, nil
	}

	out, _, err := poshCmd("Get-VMSwitch | Format-Table -Property Name, SwitchType -HideTableHeaders")
	if err != nil {
		return "", fmt.Errorf("could not get list of switches: %v", err)
	}
	switches := splitLines(out)
	for _, s := range switches {
		if len(s) == 0 {
			continue
		}
		t := strings.Split(s, " ")
		if len(t) < 2 {
			continue
		}
		if strings.Contains(t[len(t)-1:][0], "External") {
			return strings.Join(t[:len(t)-1], " "), nil
		}
	}
	return "", fmt.Errorf("could not find an external switch")
}