plugins: reconfigure bridge IP address

Add possibility to reconfigure bridge IP address when there is a new value.
New boolean flag added to net configuration to force IP change if it is need.
Otherwise code behaves as previously and throws error

plugins/main/bridge/bridge.go

@@ -35,12 +35,13 @@ const defaultBrName = "cni0"
 
 type NetConf struct {
 	types.NetConf
-	BrName      string `json:"bridge"`
-	IsGW        bool   `json:"isGateway"`
-	IsDefaultGW bool   `json:"isDefaultGateway"`
-	IPMasq      bool   `json:"ipMasq"`
-	MTU         int    `json:"mtu"`
-	HairpinMode bool   `json:"hairpinMode"`
+	BrName       string `json:"bridge"`
+	IsGW         bool   `json:"isGateway"`
+	IsDefaultGW  bool   `json:"isDefaultGateway"`
+	ForceAddress bool   `json:"forceAddress"`
+	IPMasq       bool   `json:"ipMasq"`
+	MTU          int    `json:"mtu"`
+	HairpinMode  bool   `json:"hairpinMode"`
 }
 
 func init() {
@@ -60,7 +61,7 @@ func loadNetConf(bytes []byte) (*NetConf, error) {
 	return n, nil
 }
 
-func ensureBridgeAddr(br *netlink.Bridge, ipn *net.IPNet) error {
+func ensureBridgeAddr(br *netlink.Bridge, ipn *net.IPNet, forceAddress bool) error {
 	addrs, err := netlink.AddrList(br, syscall.AF_INET)
 	if err != nil && err != syscall.ENOENT {
 		return fmt.Errorf("could not get list of IP addresses: %v", err)
@@ -74,8 +75,16 @@ func ensureBridgeAddr(br *netlink.Bridge, ipn *net.IPNet) error {
 			if a.IPNet.String() == ipnStr {
 				return nil
 			}
+
+			// If forceAddress is set to true then reconfigure IP address otherwise throw error
+			if forceAddress {
+				if err = deleteBridgeAddr(br, a.IPNet); err != nil {
+					return err
+				}
+			} else {
+				return fmt.Errorf("%q already has an IP address different from %v", br.Name, ipn.String())
+			}
 		}
-		return fmt.Errorf("%q already has an IP address different from %v", br.Name, ipn.String())
 	}
 
 	addr := &netlink.Addr{IPNet: ipn, Label: ""}
@@ -85,6 +94,24 @@ func ensureBridgeAddr(br *netlink.Bridge, ipn *net.IPNet) error {
 	return nil
 }
 
+func deleteBridgeAddr(br *netlink.Bridge, ipn *net.IPNet) error {
+	addr := &netlink.Addr{IPNet: ipn, Label: ""}
+
+	if err := netlink.LinkSetDown(br); err != nil {
+		return fmt.Errorf("could not set down bridge %q: %v", br.Name, err)
+	}
+
+	if err := netlink.AddrDel(br, addr); err != nil {
+		return fmt.Errorf("could not remove IP address from %q: %v", br.Name, err)
+	}
+
+	if err := netlink.LinkSetUp(br); err != nil {
+		return fmt.Errorf("could not set up bridge %q: %v", br.Name, err)
+	}
+
+	return nil
+}
+
 func bridgeByName(name string) (*netlink.Bridge, error) {
 	l, err := netlink.LinkByName(name)
 	if err != nil {
@@ -258,7 +285,7 @@ func cmdAdd(args *skel.CmdArgs) error {
 			Mask: result.IP4.IP.Mask,
 		}
 
-		if err = ensureBridgeAddr(br, gwn); err != nil {
+		if err = ensureBridgeAddr(br, gwn, n.ForceAddress); err != nil {
 			return err
 		}
 

plugins/main/bridge/bridge_test.go

@@ -236,4 +236,74 @@ var _ = Describe("bridge Operations", func() {
 		})
 		Expect(err).NotTo(HaveOccurred())
 	})
+
+	It("ensure bridge address", func() {
+
+		const IFNAME = "bridge0"
+		const EXPECTED_IP = "10.0.0.0/8"
+		const CHANGED_EXPECTED_IP = "10.1.2.3/16"
+
+		conf := &NetConf{
+			NetConf: types.NetConf{
+				Name: "testConfig",
+				Type: "bridge",
+			},
+			BrName: IFNAME,
+			IsGW:   true,
+			IPMasq: false,
+			MTU:    5000,
+		}
+
+		gwnFirst := &net.IPNet{
+			IP:   net.IPv4(10, 0, 0, 0),
+			Mask: net.CIDRMask(8, 32),
+		}
+
+		gwnSecond := &net.IPNet{
+			IP:   net.IPv4(10, 1, 2, 3),
+			Mask: net.CIDRMask(16, 32),
+		}
+
+		err := originalNS.Do(func(ns.NetNS) error {
+			defer GinkgoRecover()
+
+			bridge, err := setupBridge(conf)
+			Expect(err).NotTo(HaveOccurred())
+			// Check if ForceAddress has default value
+			Expect(conf.ForceAddress).To(Equal(false))
+
+			err = ensureBridgeAddr(bridge, gwnFirst, conf.ForceAddress)
+			Expect(err).NotTo(HaveOccurred())
+
+			//Check if IP address is set correctly
+			addrs, err := netlink.AddrList(bridge, syscall.AF_INET)
+			Expect(len(addrs)).To(Equal(1))
+			addr := addrs[0].IPNet.String()
+			Expect(addr).To(Equal(EXPECTED_IP))
+
+			//The bridge IP address has been changed. Error expected when ForceAddress is set to false.
+			err = ensureBridgeAddr(bridge, gwnSecond, false)
+			Expect(err).To(HaveOccurred())
+
+			//The IP address should stay the same.
+			addrs, err = netlink.AddrList(bridge, syscall.AF_INET)
+			Expect(len(addrs)).To(Equal(1))
+			addr = addrs[0].IPNet.String()
+			Expect(addr).To(Equal(EXPECTED_IP))
+
+			//Reconfigure IP when ForceAddress is set to true and IP address has been changed.
+			err = ensureBridgeAddr(bridge, gwnSecond, true)
+			Expect(err).NotTo(HaveOccurred())
+
+			//Retrieve the IP address after reconfiguration
+			addrs, err = netlink.AddrList(bridge, syscall.AF_INET)
+			Expect(len(addrs)).To(Equal(1))
+			addr = addrs[0].IPNet.String()
+			Expect(addr).To(Equal(CHANGED_EXPECTED_IP))
+
+			return nil
+		})
+		Expect(err).NotTo(HaveOccurred())
+	})
+
 })