initialize via sub-function

net/veth.go

@@ -9,7 +9,7 @@ import (
 )
 
 // create and attach local name to the Weave bridge
-func CreateAndAttachVeth(localName, peerName, bridgeName string, mtu int) (*netlink.Veth, error) {
+func CreateAndAttachVeth(localName, peerName, bridgeName string, mtu int, init func(local, guest netlink.Link) error) (*netlink.Veth, error) {
 	maybeBridge, err := netlink.LinkByName(bridgeName)
 	if err != nil {
 		return nil, fmt.Errorf(`bridge "%s" not present; did you launch weave?`, bridgeName)
@@ -54,6 +54,16 @@ func CreateAndAttachVeth(localName, peerName, bridgeName string, mtu int) (*netl
 		return cleanup(`device "%s" is not a bridge`, bridgeName)
 	}
 
+	if init != nil {
+		guest, err := netlink.LinkByName(peerName)
+		if err != nil {
+			return cleanup("unable to find guest veth %s: %s", peerName, err)
+		}
+		if err := init(local, guest); err != nil {
+			return cleanup("initializing veth: %s", err)
+		}
+	}
+
 	if err := netlink.LinkSetUp(local); err != nil {
 		return cleanup("unable to bring veth up: %s", err)
 	}

plugin/net/cni.go

@@ -95,39 +95,27 @@ func (c *CNIPlugin) CmdAdd(args *skel.CmdArgs) error {
 	}
 
 	name, peerName := vethPair(id)
-	local, err := weavenet.CreateAndAttachVeth(name, peerName, conf.BrName, conf.MTU)
-	if err != nil {
-		return err
-	}
-
-	cleanup := func(err error) error {
-		netlink.LinkDel(local)
-		return err
-	}
-	guest, err := netlink.LinkByName(local.PeerName)
-	if err != nil {
-		return cleanup(err)
-	}
-	if err = netlink.LinkSetNsFd(guest, int(ns)); err != nil {
-		return cleanup(fmt.Errorf("failed to move veth to container netns: %s", err))
-	}
-
-	err = common.WithNetNS(ns, func() error {
-		return setupGuestIP4(local.PeerName, args.IfName, result.IP4.IP, result.IP4.Gateway, result.IP4.Routes)
+	_, err = weavenet.CreateAndAttachVeth(name, peerName, conf.BrName, conf.MTU, func(local, guest netlink.Link) error {
+		if err = netlink.LinkSetNsFd(guest, int(ns)); err != nil {
+			return fmt.Errorf("failed to move veth to container netns: %s", err)
+		}
+		if err = common.WithNetNS(ns, func() error {
+			return setupGuestIP4(guest, args.IfName, result.IP4.IP, result.IP4.Gateway, result.IP4.Routes)
+		}); err != nil {
+			return fmt.Errorf("error setting up interface: %s", err)
+		}
+		return nil
 	})
 	if err != nil {
-		return cleanup(fmt.Errorf("error setting up interface: %s", err))
+		return err
 	}
 
 	result.DNS = conf.DNS
 	return result.Print()
 }
 
-func setupGuestIP4(origName, name string, ipnet net.IPNet, gw net.IP, routes []types.Route) error {
-	guest, err := netlink.LinkByName(origName)
-	if err != nil {
-		return err
-	}
+func setupGuestIP4(guest netlink.Link, name string, ipnet net.IPNet, gw net.IP, routes []types.Route) error {
+	var err error
 	if err = netlink.LinkSetName(guest, name); err != nil {
 		return err
 	}

plugin/net/driver.go

@@ -101,7 +101,7 @@ func (driver *driver) JoinEndpoint(j *api.JoinRequest) (*api.JoinResponse, error
 	driver.logReq("JoinEndpoint", j, fmt.Sprintf("%s:%s to %s", j.NetworkID, j.EndpointID, j.SandboxKey))
 
 	name, peerName := vethPair(j.EndpointID)
-	if _, err := weavenet.CreateAndAttachVeth(name, peerName, WeaveBridge, 0); err != nil {
+	if _, err := weavenet.CreateAndAttachVeth(name, peerName, WeaveBridge, 0, nil); err != nil {
 		return nil, driver.error("JoinEndpoint", "%s", err)
 	}