Refactor network creation and initialization into strategies

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

pkg/libcontainer/README.md

@@ -45,12 +45,17 @@ Sample `container.json` file:
         "AUDIT_WRITE",
         "AUDIT_CONTROL",
         "MAC_OVERRIDE",
-        "MAC_ADMIN"
+        "MAC_ADMIN",
+        "NET_ADMIN"
     ],
     "network": {
+        "type": "veth",
+        "context": {
+            "bridge": "docker0",
+            "prefix": "dock"
+        },
         "address": "172.17.0.100/16",
         "gateway": "172.17.42.1",
-        "bridge": "docker0",
         "mtu": 1500
     },
     "cgroups": {

pkg/libcontainer/container.go

@@ -4,6 +4,10 @@ import (
 	"github.com/dotcloud/docker/pkg/cgroups"
 )
 
+// Context is a generic key value pair that allows
+// arbatrary data to be sent
+type Context map[string]string
+
 // Container defines configuration options for how a
 // container is setup inside a directory and how a process should be executed
 type Container struct {
@@ -24,8 +28,9 @@ type Container struct {
 // The network configuration can be omited from a container causing the
 // container to be setup with the host's networking stack
 type Network struct {
-	Address string `json:"address,omitempty"`
+	Type    string  `json:"type,omitempty"`    // type of networking to setup i.e. veth, macvlan, etc
-	Gateway string `json:"gateway,omitempty"`
+	Context Context `json:"context,omitempty"` // generic context for type specific networking options
-	Bridge  string `json:"bridge,omitempty"`
+	Address string  `json:"address,omitempty"`
-	Mtu     int    `json:"mtu,omitempty"`
+	Gateway string  `json:"gateway,omitempty"`
+	Mtu     int     `json:"mtu,omitempty"`
 }

pkg/libcontainer/container.json

@@ -28,12 +28,17 @@
         "AUDIT_WRITE",
         "AUDIT_CONTROL",
         "MAC_OVERRIDE",
-        "MAC_ADMIN"
+        "MAC_ADMIN",
+        "NET_ADMIN"
     ],
     "network": {
+        "type": "veth",
+        "context": {
+            "bridge": "docker0",
+            "prefix": "dock"
+        },
         "address": "172.17.0.100/16",
         "gateway": "172.17.42.1",
-        "bridge": "docker0",
         "mtu": 1500
     },
     "cgroups": {

pkg/libcontainer/network/strategy.go

@@ -0,0 +1,32 @@
+package network
+
+import (
+	"errors"
+	"github.com/dotcloud/docker/pkg/libcontainer"
+)
+
+var (
+	ErrNotValidStrategyType = errors.New("not a valid network strategy type")
+)
+
+var strategies = map[string]NetworkStrategy{
+	"veth": &Veth{},
+}
+
+// NetworkStrategy represends a specific network configuration for
+// a containers networking stack
+type NetworkStrategy interface {
+	Create(*libcontainer.Network, int) (libcontainer.Context, error)
+	Initialize(*libcontainer.Network, libcontainer.Context) error
+}
+
+// GetStrategy returns the specific network strategy for the
+// provided type.  If no strategy is registered for the type an
+// ErrNotValidStrategyType is returned.
+func GetStrategy(tpe string) (NetworkStrategy, error) {
+	s, exists := strategies[tpe]
+	if !exists {
+		return nil, ErrNotValidStrategyType
+	}
+	return s, nil
+}

pkg/libcontainer/network/veth.go

@@ -0,0 +1,103 @@
+package network
+
+import (
+	"fmt"
+	"github.com/dotcloud/docker/pkg/libcontainer"
+	"github.com/dotcloud/docker/pkg/libcontainer/utils"
+	"log"
+)
+
+type Veth struct {
+}
+
+func (v *Veth) Create(n *libcontainer.Network, nspid int) (libcontainer.Context, error) {
+	log.Printf("creating veth network")
+	var (
+		bridge string
+		prefix string
+		exists bool
+	)
+	if bridge, exists = n.Context["bridge"]; !exists {
+		return nil, fmt.Errorf("bridge does not exist in network context")
+	}
+	if prefix, exists = n.Context["prefix"]; !exists {
+		return nil, fmt.Errorf("veth prefix does not exist in network context")
+	}
+	name1, name2, err := createVethPair(prefix)
+	if err != nil {
+		return nil, err
+	}
+	context := libcontainer.Context{
+		"vethHost":  name1,
+		"vethChild": name2,
+	}
+	log.Printf("veth pair created %s <> %s", name1, name2)
+	if err := SetInterfaceMaster(name1, bridge); err != nil {
+		return context, err
+	}
+	if err := SetMtu(name1, n.Mtu); err != nil {
+		return context, err
+	}
+	if err := InterfaceUp(name1); err != nil {
+		return context, err
+	}
+	log.Printf("setting %s inside %d namespace", name2, nspid)
+	if err := SetInterfaceInNamespacePid(name2, nspid); err != nil {
+		return context, err
+	}
+	return context, nil
+}
+
+func (v *Veth) Initialize(config *libcontainer.Network, context libcontainer.Context) error {
+	var (
+		vethChild string
+		exists    bool
+	)
+	if vethChild, exists = context["vethChild"]; !exists {
+		return fmt.Errorf("vethChild does not exist in network context")
+	}
+	if err := InterfaceDown(vethChild); err != nil {
+		return fmt.Errorf("interface down %s %s", vethChild, err)
+	}
+	if err := ChangeInterfaceName(vethChild, "eth0"); err != nil {
+		return fmt.Errorf("change %s to eth0 %s", vethChild, err)
+	}
+	if err := SetInterfaceIp("eth0", config.Address); err != nil {
+		return fmt.Errorf("set eth0 ip %s", err)
+	}
+	if err := SetMtu("eth0", config.Mtu); err != nil {
+		return fmt.Errorf("set eth0 mtu to %d %s", config.Mtu, err)
+	}
+	if err := InterfaceUp("eth0"); err != nil {
+		return fmt.Errorf("eth0 up %s", err)
+	}
+	if err := SetMtu("lo", config.Mtu); err != nil {
+		return fmt.Errorf("set lo mtu to %d %s", config.Mtu, err)
+	}
+	if err := InterfaceUp("lo"); err != nil {
+		return fmt.Errorf("lo up %s", err)
+	}
+	if config.Gateway != "" {
+		if err := SetDefaultGateway(config.Gateway); err != nil {
+			return fmt.Errorf("set gateway to %s %s", config.Gateway, err)
+		}
+	}
+	return nil
+}
+
+// createVethPair will automatically generage two random names for
+// the veth pair and ensure that they have been created
+func createVethPair(prefix string) (name1 string, name2 string, err error) {
+	name1, err = utils.GenerateRandomName(prefix, 4)
+	if err != nil {
+		return
+	}
+	name2, err = utils.GenerateRandomName(prefix, 4)
+	if err != nil {
+		return
+	}
+	if err = CreateVethPair(name1, name2); err != nil {
+		return
+	}
+	return
+}

pkg/libcontainer/nsinit/exec.go

@@ -3,10 +3,10 @@
 package nsinit
 
 import (
+	"encoding/json"
 	"fmt"
 	"github.com/dotcloud/docker/pkg/libcontainer"
 	"github.com/dotcloud/docker/pkg/libcontainer/network"
-	"github.com/dotcloud/docker/pkg/libcontainer/utils"
 	"github.com/dotcloud/docker/pkg/system"
 	"github.com/dotcloud/docker/pkg/term"
 	"io"
@@ -19,11 +19,11 @@ import (
 
 // Exec performes setup outside of a namespace so that a container can be
 // executed.  Exec is a high level function for working with container namespaces.
-func Exec(container *libcontainer.Container, stdin io.Reader, stdout, stderr io.Writer, master *os.File, logFile string, args []string) (int, error) {
+func Exec(container *libcontainer.Container, stdin io.Reader, stdout, stderr io.Writer,
+	master *os.File, logFile string, args []string) (int, error) {
 	var (
-		console string
+		console          string
-		err     error
+		err              error
-
 		inPipe           io.WriteCloser
 		outPipe, errPipe io.ReadCloser
 	)
@@ -46,7 +46,7 @@ func Exec(container *libcontainer.Container, stdin io.Reader, stdout, stderr io.
 
 	command := CreateCommand(container, console, logFile, r.Fd(), args)
 	if !container.Tty {
-		log.Printf("opening pipes on command")
+		log.Printf("opening std pipes")
 		if inPipe, err = command.StdinPipe(); err != nil {
 			return -1, err
 		}
@@ -78,15 +78,9 @@ func Exec(container *libcontainer.Container, stdin io.Reader, stdout, stderr io.
 			return -1, err
 		}
 	}
-
+	if err := InitializeNetworking(container, command.Process.Pid, w); err != nil {
-	if container.Network != nil {
+		command.Process.Kill()
-		log.Printf("creating veth pair")
+		return -1, err
-		vethPair, err := InitializeContainerVeth(container.Network.Bridge, container.Network.Mtu, command.Process.Pid)
-		if err != nil {
-			return -1, err
-		}
-		log.Printf("sending %s as veth pair name", vethPair)
-		SendVethName(w, vethPair)
 	}
 
 	// Sync with child
@@ -104,7 +98,7 @@ func Exec(container *libcontainer.Container, stdin io.Reader, stdout, stderr io.
 			command.Process.Kill()
 			return -1, err
 		}
-		defer term.RestoreTerminal(uintptr(syscall.Stdin), state)
+		defer term.RestoreTerminal(os.Stdin.Fd(), state)
 	} else {
 		log.Printf("starting copy for std pipes")
 		go func() {
@@ -125,39 +119,34 @@ func Exec(container *libcontainer.Container, stdin io.Reader, stdout, stderr io.
 	return command.ProcessState.Sys().(syscall.WaitStatus).ExitStatus(), nil
 }
 
-// SendVethName writes the veth pair name to the child's stdin then closes the
+func InitializeNetworking(container *libcontainer.Container, nspid int, pipe io.Writer) error {
-// pipe so that the child stops waiting for more data
+	if container.Network != nil {
-func SendVethName(pipe io.Writer, name string) {
+		log.Printf("creating host network configuration type %s", container.Network.Type)
-	fmt.Fprint(pipe, name)
+		strategy, err := network.GetStrategy(container.Network.Type)
+		if err != nil {
+			return err
+		}
+		networkContext, err := strategy.Create(container.Network, nspid)
+		if err != nil {
+			return err
+		}
+		log.Printf("sending %v as network context", networkContext)
+		if err := SendContext(pipe, networkContext); err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
-// initializeContainerVeth will create a veth pair and setup the host's
+// SendContext writes the veth pair name to the child's stdin then closes the
-// side of the pair by setting the specified bridge as the master and bringing
+// pipe so that the child stops waiting for more data
-// up the interface.
+func SendContext(pipe io.Writer, context libcontainer.Context) error {
-//
+	data, err := json.Marshal(context)
-// Then will with set the other side of the veth pair into the container's namespaced
-// using the pid and returns the veth's interface name to provide to the container to
-// finish setting up the interface inside the namespace
-func InitializeContainerVeth(bridge string, mtu, nspid int) (string, error) {
-	name1, name2, err := createVethPair()
 	if err != nil {
-		return "", err
+		return err
 	}
-	log.Printf("veth pair created %s <> %s", name1, name2)
+	pipe.Write(data)
-	if err := network.SetInterfaceMaster(name1, bridge); err != nil {
+	return nil
-		return "", err
-	}
-	if err := network.SetMtu(name1, mtu); err != nil {
-		return "", err
-	}
-	if err := network.InterfaceUp(name1); err != nil {
-		return "", err
-	}
-	log.Printf("setting %s inside %d namespace", name2, nspid)
-	if err := network.SetInterfaceInNamespacePid(name2, nspid); err != nil {
-		return "", err
-	}
-	return name2, nil
 }
 
 // SetupWindow gets the parent window size and sets the master
@@ -190,29 +179,13 @@ func CreateMasterAndConsole() (*os.File, string, error) {
 	return master, console, nil
 }
 
-// createVethPair will automatically generage two random names for
-// the veth pair and ensure that they have been created
-func createVethPair() (name1 string, name2 string, err error) {
-	name1, err = utils.GenerateRandomName("dock", 4)
-	if err != nil {
-		return
-	}
-	name2, err = utils.GenerateRandomName("dock", 4)
-	if err != nil {
-		return
-	}
-	if err = network.CreateVethPair(name1, name2); err != nil {
-		return
-	}
-	return
-}
-
 // writePidFile writes the namespaced processes pid to .nspid in the rootfs for the container
 func writePidFile(command *exec.Cmd) error {
 	return ioutil.WriteFile(".nspid", []byte(fmt.Sprint(command.Process.Pid)), 0655)
 }
 
 func deletePidFile() error {
+	log.Printf("removing .nspid file")
 	return os.Remove(".nspid")
 }
 

pkg/libcontainer/nsinit/init.go

@@ -3,6 +3,7 @@
 package nsinit
 
 import (
+	"encoding/json"
 	"fmt"
 	"github.com/dotcloud/docker/pkg/libcontainer"
 	"github.com/dotcloud/docker/pkg/libcontainer/capabilities"
@@ -27,13 +28,10 @@ func Init(container *libcontainer.Container, uncleanRootfs, console string, pipe
 	log.Printf("initializing namespace at %s", rootfs)
 
 	// We always read this as it is a way to sync with the parent as well
-	tempVethName, err := getVethName(pipe)
+	context, err := GetContextFromParent(pipe)
 	if err != nil {
 		return err
 	}
-	if tempVethName != "" {
-		log.Printf("received veth name %s", tempVethName)
-	}
 	if console != "" {
 		log.Printf("setting up console for %s", console)
 		// close pipes so that we can replace it with the pty
@@ -62,7 +60,7 @@ func Init(container *libcontainer.Container, uncleanRootfs, console string, pipe
 	if err := setupNewMountNamespace(rootfs, console, container.ReadonlyFs); err != nil {
 		return fmt.Errorf("setup mount namespace %s", err)
 	}
-	if err := setupVethNetwork(container.Network, tempVethName); err != nil {
+	if err := setupNetwork(container.Network, context); err != nil {
 		return fmt.Errorf("setup networking %s", err)
 	}
 	if err := system.Sethostname(container.Hostname); err != nil {
@@ -145,46 +143,29 @@ func openTerminal(name string, flag int) (*os.File, error) {
 // setupVethNetwork uses the Network config if it is not nil to initialize
 // the new veth interface inside the container for use by changing the name to eth0
 // setting the MTU and IP address along with the default gateway
-func setupVethNetwork(config *libcontainer.Network, tempVethName string) error {
+func setupNetwork(config *libcontainer.Network, context libcontainer.Context) error {
 	if config != nil {
-		if err := network.InterfaceDown(tempVethName); err != nil {
+		strategy, err := network.GetStrategy(config.Type)
-			return fmt.Errorf("interface down %s %s", tempVethName, err)
+		if err != nil {
-		}
+			return err
-		if err := network.ChangeInterfaceName(tempVethName, "eth0"); err != nil {
-			return fmt.Errorf("change %s to eth0 %s", tempVethName, err)
-		}
-		if err := network.SetInterfaceIp("eth0", config.Address); err != nil {
-			return fmt.Errorf("set eth0 ip %s", err)
-		}
-		if err := network.SetMtu("eth0", config.Mtu); err != nil {
-			return fmt.Errorf("set eth0 mtu to %d %s", config.Mtu, err)
-		}
-		if err := network.InterfaceUp("eth0"); err != nil {
-			return fmt.Errorf("eth0 up %s", err)
-		}
-		if err := network.SetMtu("lo", config.Mtu); err != nil {
-			return fmt.Errorf("set lo mtu to %d %s", config.Mtu, err)
-		}
-		if err := network.InterfaceUp("lo"); err != nil {
-			return fmt.Errorf("lo up %s", err)
-		}
-		if config.Gateway != "" {
-			if err := network.SetDefaultGateway(config.Gateway); err != nil {
-				return fmt.Errorf("set gateway to %s %s", config.Gateway, err)
-			}
 		}
+		return strategy.Initialize(config, context)
 	}
 	return nil
 }
 
-// getVethName reads from Stdin the temp veth name
+func GetContextFromParent(pipe io.ReadCloser) (libcontainer.Context, error) {
-// sent by the parent processes after the veth pair
-// has been created and setup
-func getVethName(pipe io.ReadCloser) (string, error) {
 	defer pipe.Close()
 	data, err := ioutil.ReadAll(pipe)
 	if err != nil {
-		return "", fmt.Errorf("error reading from stdin %s", err)
+		return nil, fmt.Errorf("error reading from stdin %s", err)
 	}
-	return string(data), nil
+	var context libcontainer.Context
+	if len(data) > 0 {
+		if err := json.Unmarshal(data, &context); err != nil {
+			return nil, err
+		}
+		log.Printf("received context %v", context)
+	}
+	return context, nil
 }