Respect --bridge=none

- Do not create the default "bridge" network
- Get rid of the docker0 bridge

Signed-off-by: Alessandro Boch <aboch@docker.com>

daemon/daemon_unix.go

@@ -39,6 +39,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/label"
 	"github.com/opencontainers/runc/libcontainer/user"
 	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/vishvananda/netlink"
 )
 
 const (
@@ -637,11 +638,21 @@ func (daemon *Daemon) initNetworkController(config *Config, activeSandboxes map[
 			return nil, fmt.Errorf("Error creating default \"host\" network: %v", err)
 		}
 	}
+
+	// Clear stale bridge network
+	if n, err := controller.NetworkByName("bridge"); err == nil {
+		if err = n.Delete(); err != nil {
+			return nil, fmt.Errorf("could not delete the default bridge network: %v", err)
+		}
+	}
+
 	if !config.DisableBridge {
 		// Initialize default driver "bridge"
 		if err := initBridgeDriver(controller, config); err != nil {
 			return nil, err
 		}
+	} else {
+		removeDefaultBridgeInterface()
 	}
 
 	return controller, nil
@@ -660,12 +671,6 @@ func driverOptions(config *Config) []nwconfig.Option {
 }
 
 func initBridgeDriver(controller libnetwork.NetworkController, config *Config) error {
-	if n, err := controller.NetworkByName("bridge"); err == nil {
-		if err = n.Delete(); err != nil {
-			return fmt.Errorf("could not delete the default bridge network: %v", err)
-		}
-	}
-
 	bridgeName := bridge.DefaultBridgeName
 	if config.bridgeConfig.Iface != "" {
 		bridgeName = config.bridgeConfig.Iface
@@ -779,6 +784,15 @@ func initBridgeDriver(controller libnetwork.NetworkController, config *Config) e
 	return nil
 }
 
+// Remove default bridge interface if present (--bridge=none use case)
+func removeDefaultBridgeInterface() {
+	if lnk, err := netlink.LinkByName(bridge.DefaultBridgeName); err == nil {
+		if err := netlink.LinkDel(lnk); err != nil {
+			logrus.Warnf("Failed to remove bridge interface (%s): %v", bridge.DefaultBridgeName, err)
+		}
+	}
+}
+
 func (daemon *Daemon) getLayerInit() func(string) error {
 	return daemon.setupInitLayer
 }

integration-cli/docker_cli_daemon_test.go

@@ -643,6 +643,24 @@ func (s *DockerDaemonSuite) TestDaemonBridgeExternal(c *check.C) {
 			containerIP))
 }
 
+func (s *DockerDaemonSuite) TestDaemonBridgeNone(c *check.C) {
+	// start with bridge none
+	d := s.d
+	err := d.StartWithBusybox("--bridge", "none")
+	c.Assert(err, check.IsNil)
+	defer d.Restart()
+
+	// verify docker0 iface is not there
+	out, _, err := runCommandWithOutput(exec.Command("ifconfig", "docker0"))
+	c.Assert(err, check.NotNil, check.Commentf("docker0 should not be present if daemon started with --bridge=none"))
+	c.Assert(strings.Contains(out, "Device not found"), check.Equals, true)
+
+	// verify default "bridge" network is not there
+	out, err = d.Cmd("network", "inspect", "bridge")
+	c.Assert(err, check.NotNil, check.Commentf("\"bridge\" network should not be present if daemon started with --bridge=none"))
+	c.Assert(strings.Contains(out, "No such network"), check.Equals, true)
+}
+
 func createInterface(c *check.C, ifType string, ifName string, ipNet string) (string, error) {
 	args := []string{"link", "add", "name", ifName, "type", ifType}
 	ipLinkCmd := exec.Command("ip", args...)