Add Virtual-IP of an endpoint as a secondary IP

Signed-off-by: Madhu Venugopal <madhu@docker.com>

libnetwork/osl/interface_linux.go

@@ -26,6 +26,7 @@ type nwIface struct {
 	mac         net.HardwareAddr
 	address     *net.IPNet
 	addressIPv6 *net.IPNet
+	ipAliases   []*net.IPNet
 	llAddrs     []*net.IPNet
 	routes      []*net.IPNet
 	bridge      bool
@@ -96,6 +97,13 @@ func (i *nwIface) LinkLocalAddresses() []*net.IPNet {
 	return i.llAddrs
 }
 
+func (i *nwIface) IPAliases() []*net.IPNet {
+	i.Lock()
+	defer i.Unlock()
+
+	return i.ipAliases
+}
+
 func (i *nwIface) Routes() []*net.IPNet {
 	i.Lock()
 	defer i.Unlock()
@@ -324,6 +332,7 @@ func configureInterface(nlh *netlink.Handle, iface netlink.Link, i *nwIface) err
 		{setInterfaceIPv6, fmt.Sprintf("error setting interface %q IPv6 to %v", ifaceName, i.AddressIPv6())},
 		{setInterfaceMaster, fmt.Sprintf("error setting interface %q master to %q", ifaceName, i.DstMaster())},
 		{setInterfaceLinkLocalIPs, fmt.Sprintf("error setting interface %q link local IPs to %v", ifaceName, i.LinkLocalAddresses())},
+		{setInterfaceIPAliases, fmt.Sprintf("error setting interface %q IP Aliases to %v", ifaceName, i.IPAliases())},
 	}
 
 	for _, config := range ifaceConfigurators {
@@ -377,6 +386,16 @@ func setInterfaceLinkLocalIPs(nlh *netlink.Handle, iface netlink.Link, i *nwIfac
 	return nil
 }
 
+func setInterfaceIPAliases(nlh *netlink.Handle, iface netlink.Link, i *nwIface) error {
+	for _, si := range i.IPAliases() {
+		ipAddr := &netlink.Addr{IPNet: si}
+		if err := nlh.AddrAdd(iface, ipAddr); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func setInterfaceName(nlh *netlink.Handle, iface netlink.Link, i *nwIface) error {
 	return nlh.LinkSetName(iface, i.DstName())
 }

libnetwork/osl/options_linux.go

@@ -66,6 +66,12 @@ func (n *networkNamespace) LinkLocalAddresses(list []*net.IPNet) IfaceOption {
 	}
 }
 
+func (n *networkNamespace) IPAliases(list []*net.IPNet) IfaceOption {
+	return func(i *nwIface) {
+		i.ipAliases = list
+	}
+}
+
 func (n *networkNamespace) Routes(routes []*net.IPNet) IfaceOption {
 	return func(i *nwIface) {
 		i.routes = routes

libnetwork/osl/sandbox.go

@@ -91,6 +91,9 @@ type IfaceOptionSetter interface {
 	// LinkLocalAddresses returns an option setter to set the link-local IP addresses.
 	LinkLocalAddresses([]*net.IPNet) IfaceOption
 
+	// IPAliases returns an option setter to set IP address Aliases
+	IPAliases([]*net.IPNet) IfaceOption
+
 	// Master returns an option setter to set the master interface if any for this
 	// interface. The master interface name should refer to the srcname of a
 	// previously added interface of type bridge.
@@ -147,6 +150,9 @@ type Interface interface {
 	// LinkLocalAddresses returns the link-local IP addresses assigned to the interface.
 	LinkLocalAddresses() []*net.IPNet
 
+	// IPAliases returns the IP address aliases assigned to the interface.
+	IPAliases() []*net.IPNet
+
 	// IP routes for the interface.
 	Routes() []*net.IPNet
 

libnetwork/sandbox.go

@@ -722,6 +722,10 @@ func (sb *sandbox) restoreOslSandbox() error {
 		if len(i.llAddrs) != 0 {
 			ifaceOptions = append(ifaceOptions, sb.osSbox.InterfaceOptions().LinkLocalAddresses(i.llAddrs))
 		}
+		if len(ep.virtualIP) != 0 {
+			vipAlias := &net.IPNet{IP: ep.virtualIP, Mask: net.CIDRMask(32, 32)}
+			ifaceOptions = append(ifaceOptions, sb.osSbox.InterfaceOptions().IPAliases([]*net.IPNet{vipAlias}))
+		}
 		Ifaces[fmt.Sprintf("%s+%s", i.srcName, i.dstPrefix)] = ifaceOptions
 		if joinInfo != nil {
 			for _, r := range joinInfo.StaticRoutes {
@@ -775,6 +779,10 @@ func (sb *sandbox) populateNetworkResources(ep *endpoint) error {
 		if len(i.llAddrs) != 0 {
 			ifaceOptions = append(ifaceOptions, sb.osSbox.InterfaceOptions().LinkLocalAddresses(i.llAddrs))
 		}
+		if len(ep.virtualIP) != 0 {
+			vipAlias := &net.IPNet{IP: ep.virtualIP, Mask: net.CIDRMask(32, 32)}
+			ifaceOptions = append(ifaceOptions, sb.osSbox.InterfaceOptions().IPAliases([]*net.IPNet{vipAlias}))
+		}
 		if i.mac != nil {
 			ifaceOptions = append(ifaceOptions, sb.osSbox.InterfaceOptions().MacAddress(i.mac))
 		}