Support driver labels

Add support for in-tree driver configuration labels
by pushing the labels which has the appropriate
prefix to the corresponding driver.

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

libnetwork/controller.go

@@ -47,6 +47,7 @@ package libnetwork
 import (
 	"fmt"
 	"net"
+	"strings"
 	"sync"
 
 	log "github.com/Sirupsen/logrus"
@@ -56,6 +57,7 @@ import (
 	"github.com/docker/libnetwork/datastore"
 	"github.com/docker/libnetwork/driverapi"
 	"github.com/docker/libnetwork/hostdiscovery"
+	"github.com/docker/libnetwork/netlabel"
 	"github.com/docker/libnetwork/sandbox"
 	"github.com/docker/libnetwork/types"
 )
@@ -187,14 +189,41 @@ func (c *controller) ConfigureNetworkDriver(networkType string, options map[stri
 
 func (c *controller) RegisterDriver(networkType string, driver driverapi.Driver, capability driverapi.Capability) error {
 	c.Lock()
-	defer c.Unlock()
 	if !config.IsValidName(networkType) {
+		c.Unlock()
 		return ErrInvalidName(networkType)
 	}
 	if _, ok := c.drivers[networkType]; ok {
+		c.Unlock()
 		return driverapi.ErrActiveRegistration(networkType)
 	}
 	c.drivers[networkType] = &driverData{driver, capability}
+
+	if c.cfg == nil {
+		c.Unlock()
+		return nil
+	}
+
+	opt := make(map[string]interface{})
+	for _, label := range c.cfg.Daemon.Labels {
+		if strings.HasPrefix(label, netlabel.DriverPrefix+"."+networkType) {
+			opt[netlabel.Key(label)] = netlabel.Value(label)
+		}
+	}
+
+	if capability.Scope == driverapi.GlobalScope {
+		opt[netlabel.KVProvider] = c.cfg.Datastore.Client.Provider
+		opt[netlabel.KVProviderURL] = c.cfg.Datastore.Client.Address
+	}
+
+	c.Unlock()
+
+	if len(opt) != 0 {
+		if err := driver.Config(opt); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }