Plumb through /proc path config to Docker plugin

net/netns.go

@@ -55,9 +55,9 @@ func WithNetNSByPath(path string, work func() error) error {
 }
 
 func NSPathByPid(pid int) string {
-	return NSPathByPidWithRoot("/", pid)
+	return NSPathByPidWithProc("/proc", pid)
 }
 
-func NSPathByPidWithRoot(root string, pid int) string {
+func NSPathByPidWithProc(procPath string, pid int) string {
-	return filepath.Join(root, fmt.Sprintf("/proc/%d/ns/net", pid))
+	return filepath.Join(procPath, fmt.Sprint(pid), "/ns/net")
 }

net/veth.go

@@ -236,7 +236,7 @@ func setupIface(procPath, ifaceName, newIfName string) error {
 }
 
 // configureARP is a helper for the Docker plugin which doesn't set the addresses itself
-func ConfigureARP(prefix, rootPath string) error {
+func ConfigureARP(prefix, procPath string) error {
 	links, err := netlink.LinkList()
 	if err != nil {
 		return err
@@ -244,7 +244,7 @@ func ConfigureARP(prefix, rootPath string) error {
 	for _, link := range links {
 		ifName := link.Attrs().Name
 		if strings.HasPrefix(ifName, prefix) {
-			configureARPCache(rootPath+"/proc", ifName)
+			configureARPCache(procPath, ifName)
 			if addrs, err := netlink.AddrList(link, netlink.FAMILY_V4); err == nil {
 				for _, addr := range addrs {
 					arping.GratuitousArpOverIfaceByName(addr.IPNet.IP, ifName)

plugin/net/driver.go

@@ -39,9 +39,10 @@ type driver struct {
 	// used only by plugin-v2
 	forceMulticast bool
 	networks       map[string]network
+	procPath       string
 }
 
-func New(client *docker.Client, weave *weaveapi.Client, name, scope string, dns, isPluginV2, forceMulticast bool) (skel.Driver, error) {
+func New(client *docker.Client, weave *weaveapi.Client, name, scope string, dns, isPluginV2, forceMulticast bool, procPath string) (skel.Driver, error) {
 	driver := &driver{
 		name:       name,
 		scope:      scope,
@@ -51,6 +52,7 @@ func New(client *docker.Client, weave *weaveapi.Client, name, scope string, dns,
 		// make sure that it's used only by plugin-v2
 		forceMulticast: isPluginV2 && forceMulticast,
 		networks:       make(map[string]network),
+		procPath:       procPath,
 	}
 
 	// Do not start watcher in the case of plugin v2, which prevents us from
@@ -134,7 +136,7 @@ func (driver *driver) CreateEndpoint(create *api.CreateEndpointRequest) (*api.Cr
 
 	// create veths. note we assume endpoint IDs are unique in the first 9 chars
 	name, peerName := vethPair(create.EndpointID)
-	if _, err := weavenet.CreateAndAttachVeth("/proc", name, peerName, weavenet.WeaveBridgeName, 0, false, true, nil); err != nil {
+	if _, err := weavenet.CreateAndAttachVeth(driver.procPath, name, peerName, weavenet.WeaveBridgeName, 0, false, true, nil); err != nil {
 		return nil, driver.error("JoinEndpoint", "%s", err)
 	}
 

plugin/net/watcher.go

@@ -43,14 +43,9 @@ func (w *watcher) ContainerStarted(id string) {
 					w.driver.warn("ContainerStarted", "unable to register %s with weaveDNS: %s", id, err)
 				}
 			}
-			rootDir := "/"
+			netNSPath := weavenet.NSPathByPidWithProc(w.driver.procPath, info.State.Pid)
-			if w.driver.isPluginV2 {
-				// We bind mount host's /proc to /host/proc for plugin-v2
-				rootDir = "/host"
-			}
-			netNSPath := weavenet.NSPathByPidWithRoot(rootDir, info.State.Pid)
 			if err := weavenet.WithNetNSByPath(netNSPath, func() error {
-				return weavenet.ConfigureARP(weavenet.VethName, rootDir)
+				return weavenet.ConfigureARP(weavenet.VethName, w.driver.procPath)
 			}); err != nil {
 				w.driver.warn("ContainerStarted", "unable to configure interfaces: %s", err)
 			}

plugin/plugin.go

@@ -32,6 +32,7 @@ type Config struct {
 	EnableV2Multicast bool
 	DNS               bool
 	DefaultSubnet     string
+	ProcPath          string // path to reach host /proc filesystem
 }
 
 type Plugin struct {
@@ -62,7 +63,7 @@ func (plugin *Plugin) run(dockerClient *docker.Client, weave *weaveapi.Client, r
 	endChan := make(chan error, 1)
 
 	if plugin.Socket != "" {
-		globalListener, err := listenAndServe(dockerClient, weave, plugin.Socket, endChan, "global", false, plugin.DNS, plugin.EnableV2, plugin.EnableV2Multicast)
+		globalListener, err := listenAndServe(dockerClient, weave, plugin.Socket, endChan, "global", false, plugin.DNS, plugin.EnableV2, plugin.EnableV2Multicast, plugin.ProcPath)
 		if err != nil {
 			return err
 		}
@@ -70,7 +71,7 @@ func (plugin *Plugin) run(dockerClient *docker.Client, weave *weaveapi.Client, r
 		defer globalListener.Close()
 	}
 	if plugin.MeshSocket != "" {
-		meshListener, err := listenAndServe(dockerClient, weave, plugin.MeshSocket, endChan, "local", true, plugin.DNS, plugin.EnableV2, plugin.EnableV2Multicast)
+		meshListener, err := listenAndServe(dockerClient, weave, plugin.MeshSocket, endChan, "local", true, plugin.DNS, plugin.EnableV2, plugin.EnableV2Multicast, plugin.ProcPath)
 		if err != nil {
 			return err
 		}
@@ -87,7 +88,7 @@ func (plugin *Plugin) run(dockerClient *docker.Client, weave *weaveapi.Client, r
 	return <-endChan
 }
 
-func listenAndServe(dockerClient *docker.Client, weave *weaveapi.Client, address string, endChan chan<- error, scope string, withIpam, dns bool, isPluginV2, forceMulticast bool) (net.Listener, error) {
+func listenAndServe(dockerClient *docker.Client, weave *weaveapi.Client, address string, endChan chan<- error, scope string, withIpam, dns bool, isPluginV2, forceMulticast bool, procPath string) (net.Listener, error) {
 	var name string
 	if isPluginV2 {
 		name = pluginV2Name
@@ -95,7 +96,7 @@ func listenAndServe(dockerClient *docker.Client, weave *weaveapi.Client, address
 		name = pluginNameFromAddress(address)
 	}
 
-	d, err := netplugin.New(dockerClient, weave, name, scope, dns, isPluginV2, forceMulticast)
+	d, err := netplugin.New(dockerClient, weave, name, scope, dns, isPluginV2, forceMulticast, procPath)
 	if err != nil {
 		return nil, err
 	}

prog/weaver/main.go

@@ -453,6 +453,7 @@ func main() {
 
 	pluginConfig.DNS = !noDNS
 	pluginConfig.DefaultSubnet = defaultSubnet.String()
+	pluginConfig.ProcPath = procPath
 	plugin := plugin.NewPlugin(pluginConfig)
 
 	// The weave script always waits for a status call to succeed,