From 83e6b65566b67700938501d6e07fbbbe0b8cf87e Mon Sep 17 00:00:00 2001
From: Lantao Liu <lantaol@google.com>
Date: Tue, 5 Jun 2018 18:25:03 +0000
Subject: [PATCH] Select ipv4 first if there is one.

Signed-off-by: Lantao Liu <lantaol@google.com>
---
 pkg/server/sandbox_run.go      | 12 +++++++++++-
 pkg/server/sandbox_run_test.go | 26 ++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/pkg/server/sandbox_run.go b/pkg/server/sandbox_run.go
index 5fa198e4a..fe216682e 100644
--- a/pkg/server/sandbox_run.go
+++ b/pkg/server/sandbox_run.go
@@ -524,7 +524,7 @@ func (c *criService) setupPod(id string, path string, config *runtime.PodSandbox
 	}
 	// Check if the default interface has IP config
 	if configs, ok := result.Interfaces[defaultIfName]; ok && len(configs.IPConfigs) > 0 {
-		return configs.IPConfigs[0].IP.String(), nil
+		return selectPodIP(configs.IPConfigs), nil
 	}
 	// If it comes here then the result was invalid so destroy the pod network and return error
 	if err := c.teardownPod(id, path, config); err != nil {
@@ -550,6 +550,16 @@ func toCNIPortMappings(criPortMappings []*runtime.PortMapping) []cni.PortMapping
 	return portMappings
 }
 
+// selectPodIP select an ip from the ip list. It prefers ipv4 more than ipv6.
+func selectPodIP(ipConfigs []*cni.IPConfig) string {
+	for _, c := range ipConfigs {
+		if c.IP.To4() != nil {
+			return c.IP.String()
+		}
+	}
+	return ipConfigs[0].IP.String()
+}
+
 // untrustedWorkload returns true if the sandbox contains untrusted workload.
 func untrustedWorkload(config *runtime.PodSandboxConfig) bool {
 	return config.GetAnnotations()[annotations.UntrustedWorkload] == "true"
diff --git a/pkg/server/sandbox_run_test.go b/pkg/server/sandbox_run_test.go
index 4808c20af..e72dfbec7 100644
--- a/pkg/server/sandbox_run_test.go
+++ b/pkg/server/sandbox_run_test.go
@@ -17,6 +17,7 @@ limitations under the License.
 package server
 
 import (
+	"net"
 	"os"
 	"path/filepath"
 	"testing"
@@ -407,6 +408,31 @@ func TestToCNIPortMappings(t *testing.T) {
 	}
 }
 
+func TestSelectPodIP(t *testing.T) {
+	for desc, test := range map[string]struct {
+		ips      []string
+		expected string
+	}{
+		"ipv4 should be picked even if ipv6 comes first": {
+			ips:      []string{"2001:db8:85a3::8a2e:370:7334", "192.168.17.43"},
+			expected: "192.168.17.43",
+		},
+		"ipv6 should be picked when there is no ipv4": {
+			ips:      []string{"2001:db8:85a3::8a2e:370:7334"},
+			expected: "2001:db8:85a3::8a2e:370:7334",
+		},
+	} {
+		t.Logf("TestCase %q", desc)
+		var ipConfigs []*cni.IPConfig
+		for _, ip := range test.ips {
+			ipConfigs = append(ipConfigs, &cni.IPConfig{
+				IP: net.ParseIP(ip),
+			})
+		}
+		assert.Equal(t, test.expected, selectPodIP(ipConfigs))
+	}
+}
+
 func TestTypeurlMarshalUnmarshalSandboxMeta(t *testing.T) {
 	for desc, test := range map[string]struct {
 		configChange func(*runtime.PodSandboxConfig)