Move awsvpc bridge expose from weave script to Go code

net/bridge.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/Sirupsen/logrus"
 	"github.com/coreos/go-iptables/iptables"
+	"github.com/j-keck/arping"
 	"github.com/pkg/errors"
 	"github.com/vishvananda/netlink"
 
@@ -442,3 +443,35 @@ func linkSetUpByName(linkName string) error {
 	}
 	return netlink.LinkSetUp(link)
 }
+
+func AddBridgeAddr(bridgeName string, addr *net.IPNet, removeDefaultRoute bool) error {
+	link, err := netlink.LinkByName(bridgeName)
+	if err != nil {
+		return errors.Wrapf(err, "AddBridgeAddr finding bridge %q", bridgeName)
+	}
+	newAddresses, err := AddAddresses(link, []*net.IPNet{addr})
+	if err != nil {
+		return errors.Wrapf(err, "adding address %v to %q", addr, bridgeName)
+	}
+	for _, ipnet := range newAddresses {
+		arping.GratuitousArpOverIfaceByName(ipnet.IP, bridgeName)
+	}
+	if removeDefaultRoute {
+		routeFilter := &netlink.Route{
+			LinkIndex: link.Attrs().Index,
+			Dst:       &net.IPNet{IP: addr.IP.Mask(addr.Mask), Mask: addr.Mask},
+			Protocol:  2, // RTPROT_KERNEL
+		}
+		filterMask := netlink.RT_FILTER_OIF | netlink.RT_FILTER_DST | netlink.RT_FILTER_PROTOCOL
+		routes, err := netlink.RouteListFiltered(netlink.FAMILY_V4, routeFilter, filterMask)
+		if err != nil {
+			return errors.Wrapf(err, "failed to get route list for bridge %q", bridgeName)
+		}
+		for _, r := range routes {
+			if err = netlink.RouteDel(&r); err != nil {
+				return errors.Wrapf(err, "failed to delete default route %+v", r)
+			}
+		}
+	}
+	return nil
+}

prog/weaver/main.go

@@ -430,9 +430,25 @@ func main() {
 		go plugin.Start(httpAddr, dockerCli, pluginSocket, pluginMeshSocket, !noDNS, enablePluginV2)
 	}
 
+	if bridgeConfig.IsAWSVPC {
+		// Run this on its own goroutine because the allocator can block
+		// We remove the default route installed by the kernel,
+		// because awsvpc has installed it as well
+		go expose(allocator, defaultSubnet, bridgeConfig.WeaveBridgeName, bridgeConfig.IsAWSVPC)
+	}
+
 	signals.SignalHandlerLoop(common.Log, router)
 }
 
+func expose(alloc *ipam.Allocator, subnet address.CIDR, bridgeName string, removeDefaultRoute bool) {
+	addr, err := alloc.Allocate("weave:expose", subnet, false, func() bool { return false })
+	checkFatal(err)
+	cidr := address.MakeCIDR(subnet, addr)
+	err = weavenet.AddBridgeAddr(bridgeName, cidr.IPNet(), removeDefaultRoute)
+	checkFatal(err)
+	Log.Printf("Bridge %q exposed on address %v", bridgeName, cidr)
+}
+
 func options() map[string]string {
 	options := make(map[string]string)
 	mflag.Visit(func(f *mflag.Flag) {

weave

@@ -474,12 +474,6 @@ expose_ip() {
         if ! ip addr show dev $BRIDGE | grep -qF $CIDR ; then
             ip addr add dev $BRIDGE $CIDR
             arp_update $BRIDGE $CIDR || true
-            # Remove a default route installed by the kernel, because awsvpc
-            # has installed it as well
-            if [ -n "$AWSVPC" ]; then
-                RCIDR=$(ip route list exact $CIDR proto kernel | head -n1 | cut -d' ' -f1)
-                [ -n "$RCIDR" ] && ip route del dev $BRIDGE proto kernel $RCIDR
-            fi
         fi
         [ -z "$FQDN" ] || when_weave_running put_dns_fqdn_no_check_alive weave:expose $FQDN $CIDR
     done
@@ -1416,7 +1410,6 @@ launch_router() {
         --resolv-conf "/var/run/weave/etc/$RESOLV_CONF_BASE" \
         "$@")
     wait_for_status $CONTAINER_NAME http_call $HTTP_ADDR
-    setup_awsvpc
 
     if [ -n "$ENABLE_PLUGIN" ]; then
         wait_for_status $CONTAINER_NAME http_call_unix $CONTAINER_NAME plugin-status.sock
@@ -1424,12 +1417,6 @@ launch_router() {
     fi
 }
 
-setup_awsvpc() {
-    if [ -n "$AWSVPC" ]; then
-        expose_ip
-    fi
-}
-
 # Recreate the parameter values that are set when the router is first launched
 fetch_router_args() {
     CONTAINER_ARGS=$(docker inspect -f '{{.Args}}' $CONTAINER_NAME) || return 1
@@ -1660,7 +1647,6 @@ EOF
         ! docker inspect -f '{{.Config.Cmd}}' $CONTAINER_NAME | grep -q -- "--awsvpc" || AWSVPC=1
         fetch_router_args
         wait_for_status $CONTAINER_NAME http_call $HTTP_ADDR
-        setup_awsvpc
         ;;
     launch-proxy)
         deprecation_warnings "$@"