Address code review feedback

Also make sure we copy the joining containers hosts and resolv.conf with
the hostname if we are joining it's network stack.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

daemon/container.go

@@ -338,7 +338,7 @@ func populateCommand(c *Container, env []string) error {
 		Interface: nil,
 	}
 
-	parts := strings.SplitN(c.hostConfig.NetworkMode, ":", 2)
+	parts := strings.SplitN(string(c.hostConfig.NetworkMode), ":", 2)
 	switch parts[0] {
 	case "none":
 	case "host":
@@ -354,9 +354,9 @@ func populateCommand(c *Container, env []string) error {
 			}
 		}
 	case "container":
-		nc := c.daemon.Get(parts[1])
+		nc, err := c.getNetworkedContainer()
-		if nc == nil {
+		if err != nil {
-			return fmt.Errorf("no such container to join network: %q", parts[1])
+			return err
 		}
 		en.ContainerID = nc.ID
 	default:
@@ -536,7 +536,8 @@ ff02::2		ip6-allrouters
 }
 
 func (container *Container) allocateNetwork() error {
-	if container.Config.NetworkDisabled || container.hostConfig.NetworkMode == "host" {
+	mode := container.hostConfig.NetworkMode
+	if container.Config.NetworkDisabled || mode.IsContainer() || mode.IsHost() {
 		return nil
 	}
 
@@ -1045,7 +1046,7 @@ func (container *Container) setupContainerDns() error {
 
 func (container *Container) initializeNetworking() error {
 	var err error
-	if container.hostConfig.NetworkMode == "host" {
+	if container.hostConfig.NetworkMode.IsHost() {
 		container.Config.Hostname, err = os.Hostname()
 		if err != nil {
 			return err
@@ -1059,6 +1060,16 @@ func (container *Container) initializeNetworking() error {
 		container.HostsPath = "/etc/hosts"
 
 		container.buildHostname()
+	} else if container.hostConfig.NetworkMode.IsContainer() {
+		// we need to get the hosts files from the container to join
+		nc, err := container.getNetworkedContainer()
+		if err != nil {
+			return err
+		}
+		container.HostsPath = nc.HostsPath
+		container.ResolvConfPath = nc.ResolvConfPath
+		container.Config.Hostname = nc.Config.Hostname
+		container.Config.Domainname = nc.Config.Domainname
 	} else if container.daemon.config.DisableNetwork {
 		container.Config.NetworkDisabled = true
 		container.buildHostnameAndHostsFiles("127.0.1.1")
@@ -1268,3 +1279,20 @@ func (container *Container) GetMountLabel() string {
 	}
 	return container.MountLabel
 }
+
+func (container *Container) getNetworkedContainer() (*Container, error) {
+	parts := strings.SplitN(string(container.hostConfig.NetworkMode), ":", 2)
+	switch parts[0] {
+	case "container":
+		nc := container.daemon.Get(parts[1])
+		if nc == nil {
+			return nil, fmt.Errorf("no such container to join network: %s", parts[1])
+		}
+		if !nc.State.IsRunning() {
+			return nil, fmt.Errorf("cannot join network of a non running container: %s", parts[1])
+		}
+		return nc, nil
+	default:
+		return nil, fmt.Errorf("network mode not set to container")
+	}
+}

runconfig/hostconfig.go

@@ -1,11 +1,24 @@
 package runconfig
 
 import (
+	"strings"
+
 	"github.com/dotcloud/docker/engine"
 	"github.com/dotcloud/docker/nat"
 	"github.com/dotcloud/docker/utils"
 )
 
+type NetworkMode string
+
+func (n NetworkMode) IsHost() bool {
+	return n == "host"
+}
+
+func (n NetworkMode) IsContainer() bool {
+	parts := strings.SplitN(string(n), ":", 2)
+	return len(parts) > 1 && parts[0] == "container"
+}
+
 type HostConfig struct {
 	Binds           []string
 	ContainerIDFile string
@@ -17,7 +30,7 @@ type HostConfig struct {
 	Dns             []string
 	DnsSearch       []string
 	VolumesFrom     []string
-	NetworkMode     string
+	NetworkMode     NetworkMode
 }
 
 func ContainerHostConfigFromJob(job *engine.Job) *HostConfig {
@@ -25,7 +38,7 @@ func ContainerHostConfigFromJob(job *engine.Job) *HostConfig {
 		ContainerIDFile: job.Getenv("ContainerIDFile"),
 		Privileged:      job.GetenvBool("Privileged"),
 		PublishAllPorts: job.GetenvBool("PublishAllPorts"),
-		NetworkMode:     job.Getenv("NetworkMode"),
+		NetworkMode:     NetworkMode(job.Getenv("NetworkMode")),
 	}
 	job.GetenvJson("LxcConf", &hostConfig.LxcConf)
 	job.GetenvJson("PortBindings", &hostConfig.PortBindings)

runconfig/parse.go

@@ -62,7 +62,7 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 		flUser            = cmd.String([]string{"u", "-user"}, "", "Username or UID")
 		flWorkingDir      = cmd.String([]string{"w", "-workdir"}, "", "Working directory inside the container")
 		flCpuShares       = cmd.Int64([]string{"c", "-cpu-shares"}, 0, "CPU shares (relative weight)")
-		flNetMode         = cmd.String([]string{"-net"}, "bridge", "Set the Network mode for the container ('bridge': creates a new network stack for the container on the docker bridge, 'none': no networking for this container, 'container:name_or_id': reuses another container network stack)")
+		flNetMode         = cmd.String([]string{"-net"}, "bridge", "Set the Network mode for the container ('bridge': creates a new network stack for the container on the docker bridge, 'none': no networking for this container, 'container:<name|id>': reuses another container network stack)")
 		// For documentation purpose
 		_ = cmd.Bool([]string{"#sig-proxy", "-sig-proxy"}, true, "Proxify all received signal to the process (even in non-tty mode)")
 		_ = cmd.String([]string{"#name", "-name"}, "", "Assign a name to the container")
@@ -200,7 +200,7 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 
 	netMode, err := parseNetMode(*flNetMode)
 	if err != nil {
-		return nil, nil, cmd, fmt.Errorf("-net: invalid net mode: %v", err)
+		return nil, nil, cmd, fmt.Errorf("--net: invalid net mode: %v", err)
 	}
 
 	config := &Config{
@@ -282,19 +282,16 @@ func parseKeyValueOpts(opts opts.ListOpts) ([]utils.KeyValuePair, error) {
 	return out, nil
 }
 
-func parseNetMode(netMode string) (string, error) {
+func parseNetMode(netMode string) (NetworkMode, error) {
 	parts := strings.Split(netMode, ":")
 	switch mode := parts[0]; mode {
-	case "bridge", "none":
+	case "bridge", "none", "host":
-		return mode, nil
 	case "container":
 		if len(parts) < 2 || parts[1] == "" {
-			return "", fmt.Errorf("'container:' netmode requires a container id or name", netMode)
+			return "", fmt.Errorf("invalid container format container:<name|id>")
 		}
-		return netMode, nil
-	case "host":
-		return netMode, nil
 	default:
-		return "", fmt.Errorf("invalid netmode: %q", netMode)
+		return "", fmt.Errorf("invalid --net: %s", netMode)
 	}
+	return NetworkMode(netMode), nil
 }