Refactor so we can call parts individually

plugin/ipam/cni.go

@@ -10,10 +10,18 @@ import (
 )
 
 func (i *Ipam) CmdAdd(args *skel.CmdArgs) error {
+	result, err := i.Allocate(args)
+	if err != nil {
+		return err
+	}
+	return result.Print()
+}
+
+func (i *Ipam) Allocate(args *skel.CmdArgs) (*types.Result, error) {
 	// extract the things we care about
 	conf, err := loadIPAMConf(args.StdinData)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	if conf == nil {
 		conf = &ipamConf{}
@@ -27,25 +35,29 @@ func (i *Ipam) CmdAdd(args *skel.CmdArgs) error {
 		var subnet *net.IPNet
 		subnet, err = types.ParseCIDR(conf.Subnet)
 		if err != nil {
-			return fmt.Errorf("subnet given in config, but not parseable: %s", err)
+			return nil, fmt.Errorf("subnet given in config, but not parseable: %s", err)
 		}
 		ipnet, err = i.weave.AllocateIPInSubnet(containerID, subnet)
 	}
 
 	if err != nil {
-		return err
+		return nil, err
 	}
-	result := types.Result{
+	result := &types.Result{
 		IP4: &types.IPConfig{
 			IP:      *ipnet,
 			Gateway: conf.Gateway,
 			Routes:  conf.Routes,
 		},
 	}
-	return result.Print()
+	return result, nil
 }
 
 func (i *Ipam) CmdDel(args *skel.CmdArgs) error {
+	return i.Release(args)
+}
+
+func (i *Ipam) Release(args *skel.CmdArgs) error {
 	return i.weave.ReleaseIPsFor(args.ContainerID)
 }
 

plugin/net/driver.go

@@ -107,39 +107,11 @@ func (driver *driver) EndpointInfo(req *api.EndpointInfoRequest) (*api.EndpointI
 }
 
 func (driver *driver) JoinEndpoint(j *api.JoinRequest) (*api.JoinResponse, error) {
-	endID := j.EndpointID
-
-	maybeBridge, err := netlink.LinkByName(WeaveBridge)
+	local, err := createAndAttach(j.EndpointID, WeaveBridge, 0)
 	if err != nil {
-		return nil, errorf(`bridge "%s" not present; did you launch weave?`, WeaveBridge)
+		return nil, err
 	}
 
-	// create and attach local name to the bridge
-	local := vethPair(endID[:5])
-	local.Attrs().MTU = maybeBridge.Attrs().MTU
-	if err := netlink.LinkAdd(local); err != nil {
-		return nil, errorf("could not create veth pair: %s", err)
-	}
-
-	switch maybeBridge.(type) {
-	case *netlink.Bridge:
-		if err := netlink.LinkSetMasterByIndex(local, maybeBridge.Attrs().Index); err != nil {
-			return nil, errorf(`unable to set master: %s`, err)
-		}
-	case *netlink.GenericLink:
-		if maybeBridge.Type() != "openvswitch" {
-			Log.Errorf("device %s is %+v", WeaveBridge, maybeBridge)
-			return nil, errorf(`device "%s" is of type "%s"`, WeaveBridge, maybeBridge.Type())
-		}
-		odp.AddDatapathInterface(WeaveBridge, local.Name)
-	case *netlink.Device:
-		Log.Warnf("kernel does not report what kind of device %s is, just %+v", WeaveBridge, maybeBridge)
-		// Assume it's our openvswitch device, and the kernel has not been updated to report the kind.
-		odp.AddDatapathInterface(WeaveBridge, local.Name)
-	default:
-		Log.Errorf("device %s is %+v", WeaveBridge, maybeBridge)
-		return nil, errorf(`device "%s" not a bridge`, WeaveBridge)
-	}
 	if err := netlink.LinkSetUp(local); err != nil {
 		return nil, errorf(`unable to bring veth up: %s`, err)
 	}
@@ -163,6 +135,43 @@ func (driver *driver) JoinEndpoint(j *api.JoinRequest) (*api.JoinResponse, error
 	return response, nil
 }
 
+// create and attach local name to the Weave bridge
+func createAndAttach(id, bridgeName string, mtu int) (*netlink.Veth, error) {
+	maybeBridge, err := netlink.LinkByName(bridgeName)
+	if err != nil {
+		return nil, errorf(`bridge "%s" not present; did you launch weave?`, bridgeName)
+	}
+
+	local := vethPair(id[:5])
+	if mtu == 0 {
+		local.Attrs().MTU = maybeBridge.Attrs().MTU
+	} else {
+		local.Attrs().MTU = mtu
+	}
+	if err := netlink.LinkAdd(local); err != nil {
+		return nil, errorf("could not create veth pair: %s", err)
+	}
+
+	switch maybeBridge.(type) {
+	case *netlink.Bridge:
+		if err := netlink.LinkSetMasterByIndex(local, maybeBridge.Attrs().Index); err != nil {
+			return nil, errorf(`unable to set master: %s`, err)
+		}
+	case *netlink.GenericLink:
+		if maybeBridge.Type() != "openvswitch" {
+			return nil, errorf(`device "%s" is of type "%s"`, bridgeName, maybeBridge.Type())
+		}
+		odp.AddDatapathInterface(bridgeName, local.Name)
+	case *netlink.Device:
+		Log.Warnf("kernel does not report what kind of device %s is, just %+v", bridgeName, maybeBridge)
+		// Assume it's our openvswitch device, and the kernel has not been updated to report the kind.
+		odp.AddDatapathInterface(bridgeName, local.Name)
+	default:
+		return nil, errorf(`device "%s" not a bridge`, bridgeName)
+	}
+	return local, nil
+}
+
 func (driver *driver) LeaveEndpoint(leave *api.LeaveRequest) error {
 	Log.Debugf("Leave request: %+v", leave)