Enable IPV6 config on Sandbaox creation on live-restore

In sandbox creation we disable IPV6 config. But this causes problem in live-restore case
where all IPV6 configs are wiped out on running container. Hence extra check has been added
take care of this issue.

Signed-off-by: selansen <elango.siva@docker.com>

libnetwork/osl/namespace_linux.go

@@ -220,9 +220,11 @@ func NewSandbox(key string, osCreate, isRestore bool) (Sandbox, error) {
 	if err != nil {
 		logrus.Warnf("Failed to set the timeout on the sandbox netlink handle sockets: %v", err)
 	}
-
+	// In live-restore mode, IPV6 entries are getting cleaned up due to below code
+	// We should retain IPV6 configrations in live-restore mode when Docker Daemon
+	// comes back. It should work as it is on other cases
 	// As starting point, disable IPv6 on all interfaces
-	if !n.isDefault {
+	if !isRestore && !n.isDefault {
 		err = setIPv6(n.path, "all", false)
 		if err != nil {
 			logrus.Warnf("Failed to disable IPv6 on all interfaces on network namespace %q: %v", n.path, err)

libnetwork/osl/sandbox_linux_test.go

@@ -316,3 +316,95 @@ func TestSetInterfaceIP(t *testing.T) {
 		t.Fatalf("Unexpected error: %v", err)
 	}
 }
+
+func TestLiveRestore(t *testing.T) {
+
+	defer testutils.SetupTestOSContext(t)()
+
+	key, err := newKey(t)
+	if err != nil {
+		t.Fatalf("Failed to obtain a key: %v", err)
+	}
+
+	s, err := NewSandbox(key, true, false)
+	if err != nil {
+		t.Fatalf("Failed to create a new sandbox: %v", err)
+	}
+	runtime.LockOSThread()
+	defer s.Destroy()
+
+	n, ok := s.(*networkNamespace)
+	if !ok {
+		t.Fatal(ok)
+	}
+	nlh := n.nlHandle
+
+	ipv4, _ := types.ParseCIDR("172.30.0.33/24")
+	ipv6, _ := types.ParseCIDR("2001:db8::44/64")
+	iface := &nwIface{address: ipv4, addressIPv6: ipv6, ns: n, dstName: "sideA"}
+
+	if err := nlh.LinkAdd(&netlink.Veth{
+		LinkAttrs: netlink.LinkAttrs{Name: "sideA"},
+		PeerName:  "sideB",
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	linkA, err := nlh.LinkByName("sideA")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	linkB, err := nlh.LinkByName("sideB")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := nlh.LinkSetUp(linkA); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := nlh.LinkSetUp(linkB); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := setInterfaceIP(nlh, linkA, iface); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := setInterfaceIPv6(nlh, linkA, iface); err != nil {
+		t.Fatal(err)
+	}
+
+	err = setInterfaceIP(nlh, linkB, iface)
+	if err == nil {
+		t.Fatalf("Expected route conflict error, but succeeded")
+	}
+	if !strings.Contains(err.Error(), "conflicts with existing route") {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	err = setInterfaceIPv6(nlh, linkB, iface)
+	if err == nil {
+		t.Fatalf("Expected route conflict error, but succeeded")
+	}
+	if !strings.Contains(err.Error(), "conflicts with existing route") {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	// Create newsandbox with Restore - TRUE
+	s, err = NewSandbox(key, true, true)
+	if err != nil {
+		t.Fatalf("Failed to create a new sandbox: %v", err)
+	}
+
+	// Check if the IPV4 & IPV6 entry present
+	// If present , we should get error in below call
+	// It shows us , we don't delete any config in live-restore case
+	if err := setInterfaceIPv6(nlh, linkA, iface); err == nil {
+		t.Fatalf("Expected route conflict error, but succeeded for IPV6 ")
+	}
+	if err := setInterfaceIP(nlh, linkA, iface); err == nil {
+		t.Fatalf("Expected route conflict error, but succeeded for IPV4 ")
+	}
+}