From 30acfcbedcdac8a8191a8508fc23ceec3024938e Mon Sep 17 00:00:00 2001
From: "Dowideit, Sven (O&A, St. Lucia)" <Sven.Dowideit@csiro.au>
Date: Tue, 30 Jan 2018 16:11:39 +1000
Subject: [PATCH] [hyperv] if no vswitch is specified, only pick the first
 external one

Signed-off-by: Dowideit, Sven (O&A, St. Lucia) <Sven.Dowideit@csiro.au>
---
 drivers/hyperv/hyperv.go | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/hyperv/hyperv.go b/drivers/hyperv/hyperv.go
index 6a46ab6d..690256b8 100644
--- a/drivers/hyperv/hyperv.go
+++ b/drivers/hyperv/hyperv.go
@@ -255,6 +255,22 @@ func (d *Driver) Create() error {
 }
 
 func (d *Driver) chooseVirtualSwitch() (string, error) {
+	if d.VSwitch == "" {
+		// Default to the first external switche and in the process avoid DockerNAT
+		stdout, err := cmdOut("(Get-VMSwitch -SwitchType External).Name")
+		if err != nil {
+			return "", err
+		}
+
+		switches := parseLines(stdout)
+
+		if len(switches) < 1 {
+			return "", fmt.Errorf("no External vswitch found. A valid vswitch must be available for this command to run. Check https://docs.docker.com/machine/drivers/hyper-v/")
+		}
+
+		return switches[0], nil
+	}
+
 	stdout, err := cmdOut("(Get-VMSwitch).Name")
 	if err != nil {
 		return "", err
@@ -262,14 +278,6 @@ func (d *Driver) chooseVirtualSwitch() (string, error) {
 
 	switches := parseLines(stdout)
 
-	if d.VSwitch == "" {
-		if len(switches) < 1 {
-			return "", fmt.Errorf("no vswitch found. A valid vswitch must be available for this command to run. Check https://docs.docker.com/machine/drivers/hyper-v/")
-		}
-
-		return switches[0], nil
-	}
-
 	found := false
 	for _, name := range switches {
 		if name == d.VSwitch {