Merge pull request #2412 from weaveworks/1803-plugin-create

Refactor plugin to create veths in CreateEndpoint



Fixes #1803.

.gitmodules

@@ -76,3 +76,6 @@
 [submodule "vendor/github.com/aws/aws-sdk-go"]
 	path = vendor/github.com/aws/aws-sdk-go
 	url = https://github.com/aws/aws-sdk-go
+[submodule "vendor/golang.org/x/sys"]
+	path = vendor/golang.org/x/sys
+	url = https://go.googlesource.com/sys

plugin/net/driver.go

@@ -8,6 +8,7 @@ import (
 	"github.com/docker/libnetwork/drivers/remote/api"
 	"github.com/docker/libnetwork/netlabel"
 	"github.com/docker/libnetwork/types"
+	"golang.org/x/sys/unix"
 
 	"github.com/vishvananda/netlink"
 	weaveapi "github.com/weaveworks/weave/api"
@@ -94,11 +95,21 @@ func (driver *driver) DeleteNetwork(delreq *api.DeleteNetworkRequest) error {
 
 func (driver *driver) CreateEndpoint(create *api.CreateEndpointRequest) (*api.CreateEndpointResponse, error) {
 	driver.logReq("CreateEndpoint", create, create.EndpointID)
+	common.Log.Debugf("interface %+v", create.Interface)
 
 	if create.Interface == nil {
 		return nil, driver.error("CreateEndpoint", "Not supported: creating an interface from within CreateEndpoint")
 	}
-	resp := &api.CreateEndpointResponse{}
+
+	// create veths. note we assume endpoint IDs are unique in the first 9 chars
+	name, peerName := vethPair(create.EndpointID)
+	if _, err := weavenet.CreateAndAttachVeth(name, peerName, weavenet.WeaveBridgeName, 0, false, nil); err != nil {
+		return nil, driver.error("JoinEndpoint", "%s", err)
+	}
+
+	// Send back the MAC address
+	link, _ := netlink.LinkByName(peerName)
+	resp := &api.CreateEndpointResponse{Interface: &api.EndpointInterface{MacAddress: link.Attrs().HardwareAddr.String()}}
 
 	driver.logRes("CreateEndpoint", resp)
 	return resp, nil
@@ -106,6 +117,17 @@ func (driver *driver) CreateEndpoint(create *api.CreateEndpointRequest) (*api.Cr
 
 func (driver *driver) DeleteEndpoint(deleteReq *api.DeleteEndpointRequest) error {
 	driver.logReq("DeleteEndpoint", deleteReq, deleteReq.EndpointID)
+	name, _ := vethPair(deleteReq.EndpointID)
+	veth := &netlink.Veth{LinkAttrs: netlink.LinkAttrs{Name: name}}
+	if err := netlink.LinkDel(veth); err != nil {
+		// Try again using the name construction from earlier plugin version,
+		// in case user has upgraded with endpoints still extant
+		veth.Name = "vethwl" + deleteReq.EndpointID[:5]
+		if err2 := netlink.LinkDel(veth); err2 != nil {
+			// Note we report the first error
+			driver.warn("LeaveEndpoint", "unable to delete veth %q: %s", name, err)
+		}
+	}
 	return nil
 }
 
@@ -122,11 +144,7 @@ func (driver *driver) JoinEndpoint(j *api.JoinRequest) (*api.JoinResponse, error
 		return nil, driver.error("JoinEndpoint", "unable to find network info: %s", err)
 	}
 
-	name, peerName := vethPair(j.EndpointID)
-	if _, err := weavenet.CreateAndAttachVeth(name, peerName, weavenet.WeaveBridgeName, 0, false, nil); err != nil {
-		return nil, driver.error("JoinEndpoint", "%s", err)
-	}
-
+	_, peerName := vethPair(j.EndpointID)
 	response := &api.JoinResponse{
 		InterfaceName: &api.InterfaceName{
 			SrcName:   peerName,
@@ -186,12 +204,6 @@ func (driver *driver) setupNetworkInfo(id string, isOurs bool, options map[strin
 
 func (driver *driver) LeaveEndpoint(leave *api.LeaveRequest) error {
 	driver.logReq("LeaveEndpoint", leave, fmt.Sprintf("%s:%s", leave.NetworkID, leave.EndpointID))
-
-	name, _ := vethPair(leave.EndpointID)
-	veth := &netlink.Veth{LinkAttrs: netlink.LinkAttrs{Name: name}}
-	if err := netlink.LinkDel(veth); err != nil {
-		driver.warn("LeaveEndpoint", "unable to delete veth: %s", err)
-	}
 	return nil
 }
 
@@ -206,7 +218,8 @@ func (driver *driver) DiscoverDelete(disco *api.DiscoveryNotification) error {
 }
 
 func vethPair(id string) (string, string) {
-	return "vethwl" + id[:5], "vethwg" + id[:5]
+	// IFNAMSIZ is buffer length; subtract 6 for "vethwl" and 1 for terminating nul
+	return "vethwl" + id[:unix.IFNAMSIZ-7], "vethwg" + id[:unix.IFNAMSIZ-7]
 }
 
 // logging