Fixes ip allocation for multi bridge networks

- Do not discard errors on ip allocation for gw and bridge
- Release addresses on network delete
- Add some context on top of ipallocator returned error
- Create ip allocator instance at driver creation, not at package init,
  otherwise this affects bridge test code where ip db is carried over
  test functions

Signed-off-by: Alessandro Boch <aboch@docker.com>

libnetwork/drivers/bridge/bridge.go

@@ -104,12 +104,9 @@ type driver struct {
 	sync.Mutex
 }
 
-func init() {
-	ipAllocator = ipallocator.New()
-}
-
 // New constructs a new bridge driver
 func newDriver() driverapi.Driver {
+	ipAllocator = ipallocator.New()
 	return &driver{networks: map[string]*bridgeNetwork{}}
 }
 
@@ -786,6 +783,18 @@ func (d *driver) DeleteNetwork(nid string) error {
 	// Programming
 	err = netlink.LinkDel(n.bridge.Link)
 
+	// Release ip addresses (ignore errors)
+	if config.FixedCIDR == nil || config.FixedCIDR.Contains(config.DefaultGatewayIPv4) {
+		if e := ipAllocator.ReleaseIP(n.bridge.bridgeIPv4, n.bridge.gatewayIPv4); e != nil {
+			logrus.Warnf("Failed to release default gateway address %s: %v", n.bridge.gatewayIPv4.String(), e)
+		}
+	}
+	if config.FixedCIDR == nil || config.FixedCIDR.Contains(n.bridge.bridgeIPv4.IP) {
+		if e := ipAllocator.ReleaseIP(n.bridge.bridgeIPv4, n.bridge.bridgeIPv4.IP); e != nil {
+			logrus.Warnf("Failed to release bridge IP %s: %v", n.bridge.bridgeIPv4.IP.String(), e)
+		}
+	}
+
 	return err
 }
 

libnetwork/drivers/bridge/bridge_test.go

@@ -637,7 +637,19 @@ func TestSetDefaultGw(t *testing.T) {
 	}
 
 	_, subnetv6, _ := net.ParseCIDR("2001:db8:ea9:9abc:b0c4::/80")
-	gw4 := bridgeNetworks[0].IP.To4()
+
+	var nw *net.IPNet
+	for _, n := range bridgeNetworks {
+		if err := netutils.CheckRouteOverlaps(n); err == nil {
+			nw = n
+			break
+		}
+	}
+	if nw == nil {
+		t.Skipf("Skip as no more automatic networks available")
+	}
+
+	gw4 := types.GetIPCopy(nw.IP).To4()
 	gw4[3] = 254
 	gw6 := net.ParseIP("2001:db8:ea9:9abc:b0c4::254")
 

libnetwork/drivers/bridge/setup_ipv4.go

@@ -62,7 +62,7 @@ func setupBridgeIPv4(config *networkConfiguration, i *bridgeInterface) error {
 		return err
 	}
 
-	log.Debugf("Creating bridge interface %q with network %s", config.BridgeName, bridgeIPv4)
+	log.Debugf("Creating bridge interface %s with network %s", config.BridgeName, bridgeIPv4)
 	if err := netlink.AddrAdd(i.Link, &netlink.Addr{IPNet: bridgeIPv4}); err != nil {
 		return &IPv4AddrAddError{IP: bridgeIPv4, Err: err}
 	}
@@ -79,7 +79,9 @@ func allocateBridgeIP(config *networkConfiguration, i *bridgeInterface) error {
 	// reserve bridge address only if it belongs to the container network
 	// (if defined), no need otherwise
 	if config.FixedCIDR == nil || config.FixedCIDR.Contains(i.bridgeIPv4.IP) {
-		ipAllocator.RequestIP(i.bridgeIPv4, i.bridgeIPv4.IP)
+		if _, err := ipAllocator.RequestIP(i.bridgeIPv4, i.bridgeIPv4.IP); err != nil {
+			return fmt.Errorf("failed to reserve bridge IP %s: %v", i.bridgeIPv4.IP.String(), err)
+		}
 	}
 	return nil
 }
@@ -120,7 +122,7 @@ func setupGatewayIPv4(config *networkConfiguration, i *bridgeInterface) error {
 	// (if defined), no need otherwise
 	if config.FixedCIDR == nil || config.FixedCIDR.Contains(config.DefaultGatewayIPv4) {
 		if _, err := ipAllocator.RequestIP(i.bridgeIPv4, config.DefaultGatewayIPv4); err != nil {
-			return err
+			return fmt.Errorf("failed to reserve default gateway %s: %v", config.DefaultGatewayIPv4.String(), err)
 		}
 	}
 

libnetwork/drivers/bridge/setup_ipv4_test.go

@@ -54,6 +54,17 @@ func TestSetupBridgeIPv4Fixed(t *testing.T) {
 func TestSetupBridgeIPv4Auto(t *testing.T) {
 	defer netutils.SetupTestNetNS(t)()
 
+	var toBeChosen *net.IPNet
+	for _, n := range bridgeNetworks {
+		if err := netutils.CheckRouteOverlaps(n); err == nil {
+			toBeChosen = n
+			break
+		}
+	}
+	if toBeChosen == nil {
+		t.Skipf("Skip as no more automatic networks available")
+	}
+
 	config, br := setupTestInterface(t)
 	if err := setupBridgeIPv4(config, br); err != nil {
 		t.Fatalf("Failed to setup bridge IPv4: %v", err)
@@ -66,14 +77,14 @@ func TestSetupBridgeIPv4Auto(t *testing.T) {
 
 	var found bool
 	for _, addr := range addrsv4 {
-		if bridgeNetworks[0].String() == addr.IPNet.String() {
+		if toBeChosen.String() == addr.IPNet.String() {
 			found = true
 			break
 		}
 	}
 
 	if !found {
-		t.Fatalf("Bridge device does not have the automatic IPv4 address %v", bridgeNetworks[0].String())
+		t.Fatalf("Bridge device does not have the automatic IPv4 address %s", toBeChosen.String())
 	}
 }