support specifying network name with docker run --net

Currently the only way to use a network created with `docker network create` is
the --publish-service option. If the extra flexibility of services is not
required, then that option has the disadvantage of making the user repeat the
container name. Another problem is that the service created persists after the
container is deleted.

This change enables usage like `docker network create blue; docker run --net
blue mycontainer`.

Signed-off-by: Rich Lane <rlane@bigswitch.com>

daemon/container_unix.go

@@ -839,6 +839,8 @@ func (container *Container) AllocateNetwork() error {
 		}
 	} else if service != "" {
 		return fmt.Errorf("conflicting options: publishing a service and network mode")
+	} else if mode.IsNamed() {
+		networkDriver = controller.Config().Daemon.DefaultDriver
 	}
 
 	if runconfig.NetworkMode(networkDriver).IsBridge() && container.daemon.config.DisableBridge {

docs/articles/networking.md

@@ -124,7 +124,7 @@ Finally, several networking options can only be provided when calling
     [Configuring DNS](#dns) and
     [Communication between containers](#between-containers)
 
- *  `--net=bridge|none|container:NAME_or_ID|host` — see
+ *  `--net=bridge|none|container:NAME_or_ID|host|NAME` — see
     [How Docker networks a container](#container-networking)
 
  *  `--mac-address=MACADDRESS...` — see
@@ -948,6 +948,9 @@ values.
     leaving you free to build any of the custom configurations explored
     in the last few sections of this document.
 
+ *  `--net=NAME` — Tells Docker to use an existing network created by
+    `docker network create`.
+
 To get an idea of the steps that are necessary if you use `--net=none`
 as described in that last bullet point, here are the commands that you
 would run to reach roughly the same configuration as if you had let

docs/reference/run.md

@@ -228,6 +228,7 @@ of the containers.
                         'none': no networking for this container
                         'container:<name|id>': reuses another container network stack
                         'host': use the host network stack inside the container
+                        '<name>': use a network created by "docker network create"
     --add-host=""    : Add a line to /etc/hosts (host:IP)
     --mac-address="" : Sets the container's Ethernet device's MAC address
 

runconfig/hostconfig_test.go

@@ -10,19 +10,19 @@ import (
 
 func TestNetworkModeTest(t *testing.T) {
 	networkModes := map[NetworkMode][]bool{
-		// private, bridge, host, container, none, default
-		"":                         {true, false, false, false, false, false},
-		"something:weird":          {true, false, false, false, false, false},
-		"bridge":                   {true, true, false, false, false, false},
-		DefaultDaemonNetworkMode(): {true, true, false, false, false, false},
-		"host":           {false, false, true, false, false, false},
-		"container:name": {false, false, false, true, false, false},
-		"none":           {true, false, false, false, true, false},
-		"default":        {true, false, false, false, false, true},
+		// private, bridge, host, container, none, default, named
+		"":                         {true, false, false, false, false, false, false},
+		"mynet":                    {true, false, false, false, false, false, true},
+		"bridge":                   {true, true, false, false, false, false, false},
+		DefaultDaemonNetworkMode(): {true, true, false, false, false, false, false},
+		"host":           {false, false, true, false, false, false, false},
+		"container:name": {false, false, false, true, false, false, false},
+		"none":           {true, false, false, false, true, false, false},
+		"default":        {true, false, false, false, false, true, false},
 	}
 	networkModeNames := map[NetworkMode]string{
 		"":                         "",
-		"something:weird":          "",
+		"mynet":                    "mynet",
 		"bridge":                   "bridge",
 		DefaultDaemonNetworkMode(): "bridge",
 		"host":           "host",

runconfig/hostconfig_unix.go

@@ -30,8 +30,9 @@ func (n NetworkMode) NetworkName() string {
 		return "none"
 	} else if n.IsDefault() {
 		return "default"
+	} else {
+		return string(n)
 	}
-	return ""
 }
 
 func (n NetworkMode) IsBridge() bool {
@@ -50,3 +51,8 @@ func (n NetworkMode) IsContainer() bool {
 func (n NetworkMode) IsNone() bool {
 	return n == "none"
 }
+
+func (n NetworkMode) IsNamed() bool {
+	return !n.IsBridge() && !n.IsHost() && !n.IsContainer() &&
+		!n.IsNone() && !n.IsDefault()
+}

runconfig/parse_test.go

@@ -231,8 +231,8 @@ func TestNetHostname(t *testing.T) {
 	if _, _, _, err := parseRun([]string{"--net=container", "img", "cmd"}); err == nil || err.Error() != "--net: invalid net mode: invalid container format container:<name|id>" {
 		t.Fatalf("Expected error with --net=container, got : %v", err)
 	}
-	if _, _, _, err := parseRun([]string{"--net=weird", "img", "cmd"}); err == nil || err.Error() != "--net: invalid net mode: invalid --net: weird" {
-		t.Fatalf("Expected error with --net=weird, got: %s", err)
+	if _, _, _, err := parseRun([]string{"--net=mynet", "img", "cmd"}); err != nil {
+		t.Fatalf("Unexpected error: %s", err)
 	}
 }
 

runconfig/parse_unix.go

@@ -10,13 +10,10 @@ import (
 func parseNetMode(netMode string) (NetworkMode, error) {
 	parts := strings.Split(netMode, ":")
 	switch mode := parts[0]; mode {
-	case "default", "bridge", "none", "host":
 	case "container":
 		if len(parts) < 2 || parts[1] == "" {
 			return "", fmt.Errorf("invalid container format container:<name|id>")
 		}
-	default:
-		return "", fmt.Errorf("invalid --net: %s", netMode)
 	}
 	return NetworkMode(netMode), nil
 }