runtime.go - third_party/github.com/moby/moby - Git at Google

 package docker

 import (
 	"container/list"
 	"fmt"
 	"github.com/dotcloud/docker/utils"
 	"io"
 	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
 	"path"
 	"sort"
 	"strings"
 	"time"
 )

 var defaultDns = []string{"8.8.8.8", "8.8.4.4"}

 type Capabilities struct {
 	MemoryLimit            bool
 	SwapLimit              bool
 	IPv4ForwardingDisabled bool
 }

 type Runtime struct {
 	root           string
 	repository     string
 	containers     *list.List
 	networkManager *NetworkManager
 	graph          *Graph
 	repositories   *TagStore
 	idIndex        *utils.TruncIndex
 	capabilities   *Capabilities
 	kernelVersion  *utils.KernelVersionInfo
 	autoRestart    bool
 	volumes        *Graph
 	srv            *Server
 	Dns            []string
 }

 var sysInitPath string

 func init() {
 	sysInitPath = utils.SelfPath()
 }

 // List returns an array of all containers registered in the runtime.
 func (runtime *Runtime) List() []*Container {
 	containers := new(History)
 	for e := runtime.containers.Front(); e != nil; e = e.Next() {
 		containers.Add(e.Value.(*Container))
 	}
 	return *containers
 }

 func (runtime *Runtime) getContainerElement(id string) *list.Element {
 	for e := runtime.containers.Front(); e != nil; e = e.Next() {
 		container := e.Value.(*Container)
 		if container.ID == id {
 			return e
 		}
 	}
 	return nil
 }

 // Get looks for a container by the specified ID or name, and returns it.
 // If the container is not found, or if an error occurs, nil is returned.
 func (runtime *Runtime) Get(name string) *Container {
 	id, err := runtime.idIndex.Get(name)
 	if err != nil {
 		return nil
 	}
 	e := runtime.getContainerElement(id)
 	if e == nil {
 		return nil
 	}
 	return e.Value.(*Container)
 }

 // Exists returns a true if a container of the specified ID or name exists,
 // false otherwise.
 func (runtime *Runtime) Exists(id string) bool {
 	return runtime.Get(id) != nil
 }

 func (runtime *Runtime) containerRoot(id string) string {
 	return path.Join(runtime.repository, id)
 }

 // Load reads the contents of a container from disk and registers
 // it with Register.
 // This is typically done at startup.
 func (runtime *Runtime) Load(id string) (*Container, error) {
 	container := &Container{root: runtime.containerRoot(id)}
 	if err := container.FromDisk(); err != nil {
 		return nil, err
 	}
 	if container.ID != id {
 		return container, fmt.Errorf("Container %s is stored at %s", container.ID, id)
 	}
 	if container.State.Running {
 		container.State.Ghost = true
 	}
 	if err := runtime.Register(container); err != nil {
 		return nil, err
 	}
 	return container, nil
 }

 // Register makes a container object usable by the runtime as <container.ID>
 func (runtime *Runtime) Register(container *Container) error {
 	if container.runtime != nil || runtime.Exists(container.ID) {
 		return fmt.Errorf("Container is already loaded")
 	}
 	if err := validateID(container.ID); err != nil {
 		return err
 	}

 	// init the wait lock
 	container.waitLock = make(chan struct{})

 	container.runtime = runtime

 	// Attach to stdout and stderr
 	container.stderr = utils.NewWriteBroadcaster()
 	container.stdout = utils.NewWriteBroadcaster()
 	// Attach to stdin
 	if container.Config.OpenStdin {
 		container.stdin, container.stdinPipe = io.Pipe()
 	} else {
 		container.stdinPipe = utils.NopWriteCloser(ioutil.Discard) // Silently drop stdin
 	}
 	// done
 	runtime.containers.PushBack(container)
 	runtime.idIndex.Add(container.ID)

 	// When we actually restart, Start() do the monitoring.
 	// However, when we simply 'reattach', we have to restart a monitor
 	nomonitor := false

 	// FIXME: if the container is supposed to be running but is not, auto restart it?
 	//        if so, then we need to restart monitor and init a new lock
 	// If the container is supposed to be running, make sure of it
 	if container.State.Running {
 		output, err := exec.Command("lxc-info", "-n", container.ID).CombinedOutput()
 		if err != nil {
 			return err
 		}
 		if !strings.Contains(string(output), "RUNNING") {
 			utils.Debugf("Container %s was supposed to be running be is not.", container.ID)
 			if runtime.autoRestart {
 				utils.Debugf("Restarting")
 				container.State.Ghost = false
 				container.State.setStopped(0)
 				hostConfig := &HostConfig{}
 				if err := container.Start(hostConfig); err != nil {
 					return err
 				}
 				nomonitor = true
 			} else {
 				utils.Debugf("Marking as stopped")
 				container.State.setStopped(-127)
 				if err := container.ToDisk(); err != nil {
 					return err
 				}
 			}
 		}
 	}

 	// If the container is not running or just has been flagged not running
 	// then close the wait lock chan (will be reset upon start)
 	if !container.State.Running {
 		close(container.waitLock)
 	} else if !nomonitor {
 		container.allocateNetwork()
 		go container.monitor()
 	}
 	return nil
 }

 func (runtime *Runtime) LogToDisk(src *utils.WriteBroadcaster, dst, stream string) error {
 	log, err := os.OpenFile(dst, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0600)
 	if err != nil {
 		return err
 	}
 	src.AddWriter(log, stream)
 	return nil
 }

 // Destroy unregisters a container from the runtime and cleanly removes its contents from the filesystem.
 func (runtime *Runtime) Destroy(container *Container) error {
 	if container == nil {
 		return fmt.Errorf("The given container is <nil>")
 	}

 	element := runtime.getContainerElement(container.ID)
 	if element == nil {
 		return fmt.Errorf("Container %v not found - maybe it was already destroyed?", container.ID)
 	}

 	if err := container.Stop(3); err != nil {
 		return err
 	}
 	if mounted, err := container.Mounted(); err != nil {
 		return err
 	} else if mounted {
 		if err := container.Unmount(); err != nil {
 			return fmt.Errorf("Unable to unmount container %v: %v", container.ID, err)
 		}
 	}
 	// Deregister the container before removing its directory, to avoid race conditions
 	runtime.idIndex.Delete(container.ID)
 	runtime.containers.Remove(element)
 	if err := os.RemoveAll(container.root); err != nil {
 		return fmt.Errorf("Unable to remove filesystem for %v: %v", container.ID, err)
 	}
 	return nil
 }

 func (runtime *Runtime) restore() error {
 	wheel := "-\\|/"
 	if os.Getenv("DEBUG") == "" && os.Getenv("TEST") == "" {
 		fmt.Printf("Loading containers:  ")
 	}
 	dir, err := ioutil.ReadDir(runtime.repository)
 	if err != nil {
 		return err
 	}
 	for i, v := range dir {
 		id := v.Name()
 		container, err := runtime.Load(id)
 		if i%21 == 0 && os.Getenv("DEBUG") == "" && os.Getenv("TEST") == "" {
 			fmt.Printf("\b%c", wheel[i%4])
 		}
 		if err != nil {
 			utils.Debugf("Failed to load container %v: %v", id, err)
 			continue
 		}
 		utils.Debugf("Loaded container %v", container.ID)
 	}
 	if os.Getenv("DEBUG") == "" && os.Getenv("TEST") == "" {
 		fmt.Printf("\bdone.\n")
 	}
 	return nil
 }

 // FIXME: comment please!
 func (runtime *Runtime) UpdateCapabilities(quiet bool) {
 	if cgroupMemoryMountpoint, err := utils.FindCgroupMountpoint("memory"); err != nil {
 		if !quiet {
 			log.Printf("WARNING: %s\n", err)
 		}
 	} else {
 		_, err1 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.limit_in_bytes"))
 		_, err2 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.soft_limit_in_bytes"))
 		runtime.capabilities.MemoryLimit = err1 == nil && err2 == nil
 		if !runtime.capabilities.MemoryLimit && !quiet {
 			log.Printf("WARNING: Your kernel does not support cgroup memory limit.")
 		}

 		_, err = ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.memsw.limit_in_bytes"))
 		runtime.capabilities.SwapLimit = err == nil
 		if !runtime.capabilities.SwapLimit && !quiet {
 			log.Printf("WARNING: Your kernel does not support cgroup swap limit.")
 		}
 	}

 	content, err3 := ioutil.ReadFile("/proc/sys/net/ipv4/ip_forward")
 	runtime.capabilities.IPv4ForwardingDisabled = err3 != nil || len(content) == 0 || content[0] != '1'
 	if runtime.capabilities.IPv4ForwardingDisabled && !quiet {
 		log.Printf("WARNING: IPv4 forwarding is disabled.")
 	}
 }

 // Create creates a new container from the given configuration.
 func (runtime *Runtime) Create(config *Config) (*Container, error) {
 	// Lookup image
 	img, err := runtime.repositories.LookupImage(config.Image)
 	if err != nil {
 		return nil, err
 	}

 	if img.Config != nil {
 		MergeConfig(config, img.Config)
 	}

 	if len(config.Entrypoint) != 0 && config.Cmd == nil {
 		config.Cmd = []string{}
 	} else if config.Cmd == nil || len(config.Cmd) == 0 {
 		return nil, fmt.Errorf("No command specified")
 	}

 	// Generate id
 	id := GenerateID()
 	// Generate default hostname
 	// FIXME: the lxc template no longer needs to set a default hostname
 	if config.Hostname == "" {
 		config.Hostname = id[:12]
 	}

 	var args []string
 	var entrypoint string

 	if len(config.Entrypoint) != 0 {
 		entrypoint = config.Entrypoint[0]
 		args = append(config.Entrypoint[1:], config.Cmd...)
 	} else {
 		entrypoint = config.Cmd[0]
 		args = config.Cmd[1:]
 	}

 	container := &Container{
 		// FIXME: we should generate the ID here instead of receiving it as an argument
 		ID:              id,
 		Created:         time.Now(),
 		Path:            entrypoint,
 		Args:            args, //FIXME: de-duplicate from config
 		Config:          config,
 		Image:           img.ID, // Always use the resolved image id
 		NetworkSettings: &NetworkSettings{},
 		// FIXME: do we need to store this in the container?
 		SysInitPath: sysInitPath,
 	}
 	container.root = runtime.containerRoot(container.ID)
 	// Step 1: create the container directory.
 	// This doubles as a barrier to avoid race conditions.
 	if err := os.Mkdir(container.root, 0700); err != nil {
 		return nil, err
 	}

 	resolvConf, err := utils.GetResolvConf()
 	if err != nil {
 		return nil, err
 	}

 	if len(config.Dns) == 0 && len(runtime.Dns) == 0 && utils.CheckLocalDns(resolvConf) {
 		//"WARNING: Docker detected local DNS server on resolv.conf. Using default external servers: %v", defaultDns
 		runtime.Dns = defaultDns
 	}

 	// If custom dns exists, then create a resolv.conf for the container
 	if len(config.Dns) > 0 || len(runtime.Dns) > 0 {
 		var dns []string
 		if len(config.Dns) > 0 {
 			dns = config.Dns
 		} else {
 			dns = runtime.Dns
 		}
 		container.ResolvConfPath = path.Join(container.root, "resolv.conf")
 		f, err := os.Create(container.ResolvConfPath)
 		if err != nil {
 			return nil, err
 		}
 		defer f.Close()
 		for _, dns := range dns {
 			if _, err := f.Write([]byte("nameserver " + dns + "\n")); err != nil {
 				return nil, err
 			}
 		}
 	} else {
 		container.ResolvConfPath = "/etc/resolv.conf"
 	}

 	// Step 2: save the container json
 	if err := container.ToDisk(); err != nil {
 		return nil, err
 	}

 	// Step 3: if hostname, build hostname and hosts files
 	container.HostnamePath = path.Join(container.root, "hostname")
 	ioutil.WriteFile(container.HostnamePath, []byte(container.Config.Hostname+"\n"), 0644)

 	hostsContent := []byte(`
 127.0.0.1	localhost
 ::1		localhost ip6-localhost ip6-loopback
 fe00::0		ip6-localnet
 ff00::0		ip6-mcastprefix
 ff02::1		ip6-allnodes
 ff02::2		ip6-allrouters
 `)

 	container.HostsPath = path.Join(container.root, "hosts")

 	if container.Config.Domainname != "" {
 		hostsContent = append([]byte(fmt.Sprintf("::1\t\t%s.%s %s\n", container.Config.Hostname, container.Config.Domainname, container.Config.Hostname)), hostsContent...)
 		hostsContent = append([]byte(fmt.Sprintf("127.0.0.1\t%s.%s %s\n", container.Config.Hostname, container.Config.Domainname, container.Config.Hostname)), hostsContent...)
 	} else {
 		hostsContent = append([]byte(fmt.Sprintf("::1\t\t%s\n", container.Config.Hostname)), hostsContent...)
 		hostsContent = append([]byte(fmt.Sprintf("127.0.0.1\t%s\n", container.Config.Hostname)), hostsContent...)
 	}

 	ioutil.WriteFile(container.HostsPath, hostsContent, 0644)

 	// Step 4: register the container
 	if err := runtime.Register(container); err != nil {
 		return nil, err
 	}
 	return container, nil
 }

 // Commit creates a new filesystem image from the current state of a container.
 // The image can optionally be tagged into a repository
 func (runtime *Runtime) Commit(container *Container, repository, tag, comment, author string, config *Config) (*Image, error) {
 	// FIXME: freeze the container before copying it to avoid data corruption?
 	// FIXME: this shouldn't be in commands.
 	if err := container.EnsureMounted(); err != nil {
 		return nil, err
 	}

 	rwTar, err := container.ExportRw()
 	if err != nil {
 		return nil, err
 	}
 	// Create a new image from the container's base layers + a new layer from container changes
 	img, err := runtime.graph.Create(rwTar, container, comment, author, config)
 	if err != nil {
 		return nil, err
 	}
 	// Register the image if needed
 	if repository != "" {
 		if err := runtime.repositories.Set(repository, tag, img.ID, true); err != nil {
 			return img, err
 		}
 	}
 	return img, nil
 }

 // FIXME: harmonize with NewGraph()
 func NewRuntime(flGraphPath string, autoRestart bool, dns []string) (*Runtime, error) {
 	runtime, err := NewRuntimeFromDirectory(flGraphPath, autoRestart)
 	if err != nil {
 		return nil, err
 	}
 	runtime.Dns = dns

 	if k, err := utils.GetKernelVersion(); err != nil {
 		log.Printf("WARNING: %s\n", err)
 	} else {
 		runtime.kernelVersion = k
 		if utils.CompareKernelVersion(k, &utils.KernelVersionInfo{Kernel: 3, Major: 8, Minor: 0}) < 0 {
 			log.Printf("WARNING: You are running linux kernel version %s, which might be unstable running docker. Please upgrade your kernel to 3.8.0.", k.String())
 		}
 	}
 	runtime.UpdateCapabilities(false)
 	return runtime, nil
 }

 func NewRuntimeFromDirectory(root string, autoRestart bool) (*Runtime, error) {
 	runtimeRepo := path.Join(root, "containers")

 	if err := os.MkdirAll(runtimeRepo, 0700); err != nil && !os.IsExist(err) {
 		return nil, err
 	}

 	g, err := NewGraph(path.Join(root, "graph"))
 	if err != nil {
 		return nil, err
 	}
 	volumes, err := NewGraph(path.Join(root, "volumes"))
 	if err != nil {
 		return nil, err
 	}
 	repositories, err := NewTagStore(path.Join(root, "repositories"), g)
 	if err != nil {
 		return nil, fmt.Errorf("Couldn't create Tag store: %s", err)
 	}
 	if NetworkBridgeIface == "" {
 		NetworkBridgeIface = DefaultNetworkBridge
 	}
 	netManager, err := newNetworkManager(NetworkBridgeIface)
 	if err != nil {
 		return nil, err
 	}
 	runtime := &Runtime{
 		root:           root,
 		repository:     runtimeRepo,
 		containers:     list.New(),
 		networkManager: netManager,
 		graph:          g,
 		repositories:   repositories,
 		idIndex:        utils.NewTruncIndex(),
 		capabilities:   &Capabilities{},
 		autoRestart:    autoRestart,
 		volumes:        volumes,
 	}

 	if err := runtime.restore(); err != nil {
 		return nil, err
 	}
 	return runtime, nil
 }

 // History is a convenience type for storing a list of containers,
 // ordered by creation date.
 type History []*Container

 func (history *History) Len() int {
 	return len(*history)
 }

 func (history *History) Less(i, j int) bool {
 	containers := *history
 	return containers[j].When().Before(containers[i].When())
 }

 func (history *History) Swap(i, j int) {
 	containers := *history
 	tmp := containers[i]
 	containers[i] = containers[j]
 	containers[j] = tmp
 }

 func (history *History) Add(container *Container) {
 	*history = append(*history, container)
 	sort.Sort(history)
 }
	package docker

	import (
	"container/list"
	"fmt"
	"github.com/dotcloud/docker/utils"
	"io"
	"io/ioutil"
	"log"
	"os"
	"os/exec"
	"path"
	"sort"
	"strings"
	"time"
	)

	var defaultDns = []string{"8.8.8.8", "8.8.4.4"}

	type Capabilities struct {
	MemoryLimit bool
	SwapLimit bool
	IPv4ForwardingDisabled bool
	}

	type Runtime struct {
	root string
	repository string
	containers *list.List
	networkManager *NetworkManager
	graph *Graph
	repositories *TagStore
	idIndex *utils.TruncIndex
	capabilities *Capabilities
	kernelVersion *utils.KernelVersionInfo
	autoRestart bool
	volumes *Graph
	srv *Server
	Dns []string
	}

	var sysInitPath string

	func init() {
	sysInitPath = utils.SelfPath()
	}

	// List returns an array of all containers registered in the runtime.
	func (runtime Runtime) List() []Container {
	containers := new(History)
	for e := runtime.containers.Front(); e != nil; e = e.Next() {
	containers.Add(e.Value.(*Container))
	}
	return *containers
	}

	func (runtime Runtime) getContainerElement(id string) list.Element {
	for e := runtime.containers.Front(); e != nil; e = e.Next() {
	container := e.Value.(*Container)
	if container.ID == id {
	return e
	}
	}
	return nil
	}

	// Get looks for a container by the specified ID or name, and returns it.
	// If the container is not found, or if an error occurs, nil is returned.
	func (runtime Runtime) Get(name string) Container {
	id, err := runtime.idIndex.Get(name)
	if err != nil {
	return nil
	}
	e := runtime.getContainerElement(id)
	if e == nil {
	return nil
	}
	return e.Value.(*Container)
	}

	// Exists returns a true if a container of the specified ID or name exists,
	// false otherwise.
	func (runtime *Runtime) Exists(id string) bool {
	return runtime.Get(id) != nil
	}

	func (runtime *Runtime) containerRoot(id string) string {
	return path.Join(runtime.repository, id)
	}

	// Load reads the contents of a container from disk and registers
	// it with Register.
	// This is typically done at startup.
	func (runtime Runtime) Load(id string) (Container, error) {
	container := &Container{root: runtime.containerRoot(id)}
	if err := container.FromDisk(); err != nil {
	return nil, err
	}
	if container.ID != id {
	return container, fmt.Errorf("Container %s is stored at %s", container.ID, id)
	}
	if container.State.Running {
	container.State.Ghost = true
	}
	if err := runtime.Register(container); err != nil {
	return nil, err
	}
	return container, nil
	}

	// Register makes a container object usable by the runtime as <container.ID>
	func (runtime Runtime) Register(container Container) error {
	if container.runtime != nil \|\| runtime.Exists(container.ID) {
	return fmt.Errorf("Container is already loaded")
	}
	if err := validateID(container.ID); err != nil {
	return err
	}

	// init the wait lock
	container.waitLock = make(chan struct{})

	container.runtime = runtime

	// Attach to stdout and stderr
	container.stderr = utils.NewWriteBroadcaster()
	container.stdout = utils.NewWriteBroadcaster()
	// Attach to stdin
	if container.Config.OpenStdin {
	container.stdin, container.stdinPipe = io.Pipe()
	} else {
	container.stdinPipe = utils.NopWriteCloser(ioutil.Discard) // Silently drop stdin
	}
	// done
	runtime.containers.PushBack(container)
	runtime.idIndex.Add(container.ID)

	// When we actually restart, Start() do the monitoring.
	// However, when we simply 'reattach', we have to restart a monitor
	nomonitor := false

	// FIXME: if the container is supposed to be running but is not, auto restart it?
	// if so, then we need to restart monitor and init a new lock
	// If the container is supposed to be running, make sure of it
	if container.State.Running {
	output, err := exec.Command("lxc-info", "-n", container.ID).CombinedOutput()
	if err != nil {
	return err
	}
	if !strings.Contains(string(output), "RUNNING") {
	utils.Debugf("Container %s was supposed to be running be is not.", container.ID)
	if runtime.autoRestart {
	utils.Debugf("Restarting")
	container.State.Ghost = false
	container.State.setStopped(0)
	hostConfig := &HostConfig{}
	if err := container.Start(hostConfig); err != nil {
	return err
	}
	nomonitor = true
	} else {
	utils.Debugf("Marking as stopped")
	container.State.setStopped(-127)
	if err := container.ToDisk(); err != nil {
	return err
	}
	}
	}
	}

	// If the container is not running or just has been flagged not running
	// then close the wait lock chan (will be reset upon start)
	if !container.State.Running {
	close(container.waitLock)
	} else if !nomonitor {
	container.allocateNetwork()
	go container.monitor()
	}
	return nil
	}

	func (runtime Runtime) LogToDisk(src utils.WriteBroadcaster, dst, stream string) error {
	log, err := os.OpenFile(dst, os.O_RDWR\|os.O_APPEND\|os.O_CREATE, 0600)
	if err != nil {
	return err
	}
	src.AddWriter(log, stream)
	return nil
	}

	// Destroy unregisters a container from the runtime and cleanly removes its contents from the filesystem.
	func (runtime Runtime) Destroy(container Container) error {
	if container == nil {
	return fmt.Errorf("The given container is <nil>")
	}

	element := runtime.getContainerElement(container.ID)
	if element == nil {
	return fmt.Errorf("Container %v not found - maybe it was already destroyed?", container.ID)
	}

	if err := container.Stop(3); err != nil {
	return err
	}
	if mounted, err := container.Mounted(); err != nil {
	return err
	} else if mounted {
	if err := container.Unmount(); err != nil {
	return fmt.Errorf("Unable to unmount container %v: %v", container.ID, err)
	}
	}
	// Deregister the container before removing its directory, to avoid race conditions
	runtime.idIndex.Delete(container.ID)
	runtime.containers.Remove(element)
	if err := os.RemoveAll(container.root); err != nil {
	return fmt.Errorf("Unable to remove filesystem for %v: %v", container.ID, err)
	}
	return nil
	}

	func (runtime *Runtime) restore() error {
	wheel := "-\\\|/"
	if os.Getenv("DEBUG") == "" && os.Getenv("TEST") == "" {
	fmt.Printf("Loading containers: ")
	}
	dir, err := ioutil.ReadDir(runtime.repository)
	if err != nil {
	return err
	}
	for i, v := range dir {
	id := v.Name()
	container, err := runtime.Load(id)
	if i%21 == 0 && os.Getenv("DEBUG") == "" && os.Getenv("TEST") == "" {
	fmt.Printf("\b%c", wheel[i%4])
	}
	if err != nil {
	utils.Debugf("Failed to load container %v: %v", id, err)
	continue
	}
	utils.Debugf("Loaded container %v", container.ID)
	}
	if os.Getenv("DEBUG") == "" && os.Getenv("TEST") == "" {
	fmt.Printf("\bdone.\n")
	}
	return nil
	}

	// FIXME: comment please!
	func (runtime *Runtime) UpdateCapabilities(quiet bool) {
	if cgroupMemoryMountpoint, err := utils.FindCgroupMountpoint("memory"); err != nil {
	if !quiet {
	log.Printf("WARNING: %s\n", err)
	}
	} else {
	_, err1 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.limit_in_bytes"))
	_, err2 := ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.soft_limit_in_bytes"))
	runtime.capabilities.MemoryLimit = err1 == nil && err2 == nil
	if !runtime.capabilities.MemoryLimit && !quiet {
	log.Printf("WARNING: Your kernel does not support cgroup memory limit.")
	}

	_, err = ioutil.ReadFile(path.Join(cgroupMemoryMountpoint, "memory.memsw.limit_in_bytes"))
	runtime.capabilities.SwapLimit = err == nil
	if !runtime.capabilities.SwapLimit && !quiet {
	log.Printf("WARNING: Your kernel does not support cgroup swap limit.")
	}
	}

	content, err3 := ioutil.ReadFile("/proc/sys/net/ipv4/ip_forward")
	runtime.capabilities.IPv4ForwardingDisabled = err3 != nil \|\| len(content) == 0 \|\| content[0] != '1'
	if runtime.capabilities.IPv4ForwardingDisabled && !quiet {
	log.Printf("WARNING: IPv4 forwarding is disabled.")
	}
	}

	// Create creates a new container from the given configuration.
	func (runtime Runtime) Create(config Config) (*Container, error) {
	// Lookup image
	img, err := runtime.repositories.LookupImage(config.Image)
	if err != nil {
	return nil, err
	}

	if img.Config != nil {
	MergeConfig(config, img.Config)
	}

	if len(config.Entrypoint) != 0 && config.Cmd == nil {
	config.Cmd = []string{}
	} else if config.Cmd == nil \|\| len(config.Cmd) == 0 {
	return nil, fmt.Errorf("No command specified")
	}

	// Generate id
	id := GenerateID()
	// Generate default hostname
	// FIXME: the lxc template no longer needs to set a default hostname
	if config.Hostname == "" {
	config.Hostname = id[:12]
	}

	var args []string
	var entrypoint string

	if len(config.Entrypoint) != 0 {
	entrypoint = config.Entrypoint[0]
	args = append(config.Entrypoint[1:], config.Cmd...)
	} else {
	entrypoint = config.Cmd[0]
	args = config.Cmd[1:]
	}

	container := &Container{
	// FIXME: we should generate the ID here instead of receiving it as an argument
	ID: id,
	Created: time.Now(),
	Path: entrypoint,
	Args: args, //FIXME: de-duplicate from config
	Config: config,
	Image: img.ID, // Always use the resolved image id
	NetworkSettings: &NetworkSettings{},
	// FIXME: do we need to store this in the container?
	SysInitPath: sysInitPath,
	}
	container.root = runtime.containerRoot(container.ID)
	// Step 1: create the container directory.
	// This doubles as a barrier to avoid race conditions.
	if err := os.Mkdir(container.root, 0700); err != nil {
	return nil, err
	}

	resolvConf, err := utils.GetResolvConf()
	if err != nil {
	return nil, err
	}

	if len(config.Dns) == 0 && len(runtime.Dns) == 0 && utils.CheckLocalDns(resolvConf) {
	//"WARNING: Docker detected local DNS server on resolv.conf. Using default external servers: %v", defaultDns
	runtime.Dns = defaultDns
	}

	// If custom dns exists, then create a resolv.conf for the container
	if len(config.Dns) > 0 \|\| len(runtime.Dns) > 0 {
	var dns []string
	if len(config.Dns) > 0 {
	dns = config.Dns
	} else {
	dns = runtime.Dns
	}
	container.ResolvConfPath = path.Join(container.root, "resolv.conf")
	f, err := os.Create(container.ResolvConfPath)
	if err != nil {
	return nil, err
	}
	defer f.Close()
	for _, dns := range dns {
	if _, err := f.Write([]byte("nameserver " + dns + "\n")); err != nil {
	return nil, err
	}
	}
	} else {
	container.ResolvConfPath = "/etc/resolv.conf"
	}

	// Step 2: save the container json
	if err := container.ToDisk(); err != nil {
	return nil, err
	}

	// Step 3: if hostname, build hostname and hosts files
	container.HostnamePath = path.Join(container.root, "hostname")
	ioutil.WriteFile(container.HostnamePath, []byte(container.Config.Hostname+"\n"), 0644)

	hostsContent := []byte(`
	127.0.0.1 localhost
	::1 localhost ip6-localhost ip6-loopback
	fe00::0 ip6-localnet
	ff00::0 ip6-mcastprefix
	ff02::1 ip6-allnodes
	ff02::2 ip6-allrouters
	`)

	container.HostsPath = path.Join(container.root, "hosts")

	if container.Config.Domainname != "" {
	hostsContent = append([]byte(fmt.Sprintf("::1\t\t%s.%s %s\n", container.Config.Hostname, container.Config.Domainname, container.Config.Hostname)), hostsContent...)
	hostsContent = append([]byte(fmt.Sprintf("127.0.0.1\t%s.%s %s\n", container.Config.Hostname, container.Config.Domainname, container.Config.Hostname)), hostsContent...)
	} else {
	hostsContent = append([]byte(fmt.Sprintf("::1\t\t%s\n", container.Config.Hostname)), hostsContent...)
	hostsContent = append([]byte(fmt.Sprintf("127.0.0.1\t%s\n", container.Config.Hostname)), hostsContent...)
	}

	ioutil.WriteFile(container.HostsPath, hostsContent, 0644)

	// Step 4: register the container
	if err := runtime.Register(container); err != nil {
	return nil, err
	}
	return container, nil
	}

	// Commit creates a new filesystem image from the current state of a container.
	// The image can optionally be tagged into a repository
	func (runtime Runtime) Commit(container Container, repository, tag, comment, author string, config Config) (Image, error) {
	// FIXME: freeze the container before copying it to avoid data corruption?
	// FIXME: this shouldn't be in commands.
	if err := container.EnsureMounted(); err != nil {
	return nil, err
	}

	rwTar, err := container.ExportRw()
	if err != nil {
	return nil, err
	}
	// Create a new image from the container's base layers + a new layer from container changes
	img, err := runtime.graph.Create(rwTar, container, comment, author, config)
	if err != nil {
	return nil, err
	}
	// Register the image if needed
	if repository != "" {
	if err := runtime.repositories.Set(repository, tag, img.ID, true); err != nil {
	return img, err
	}
	}
	return img, nil
	}

	// FIXME: harmonize with NewGraph()
	func NewRuntime(flGraphPath string, autoRestart bool, dns []string) (*Runtime, error) {
	runtime, err := NewRuntimeFromDirectory(flGraphPath, autoRestart)
	if err != nil {
	return nil, err
	}
	runtime.Dns = dns

	if k, err := utils.GetKernelVersion(); err != nil {
	log.Printf("WARNING: %s\n", err)
	} else {
	runtime.kernelVersion = k
	if utils.CompareKernelVersion(k, &utils.KernelVersionInfo{Kernel: 3, Major: 8, Minor: 0}) < 0 {
	log.Printf("WARNING: You are running linux kernel version %s, which might be unstable running docker. Please upgrade your kernel to 3.8.0.", k.String())
	}
	}
	runtime.UpdateCapabilities(false)
	return runtime, nil
	}

	func NewRuntimeFromDirectory(root string, autoRestart bool) (*Runtime, error) {
	runtimeRepo := path.Join(root, "containers")

	if err := os.MkdirAll(runtimeRepo, 0700); err != nil && !os.IsExist(err) {
	return nil, err
	}

	g, err := NewGraph(path.Join(root, "graph"))
	if err != nil {
	return nil, err
	}
	volumes, err := NewGraph(path.Join(root, "volumes"))
	if err != nil {
	return nil, err
	}
	repositories, err := NewTagStore(path.Join(root, "repositories"), g)
	if err != nil {
	return nil, fmt.Errorf("Couldn't create Tag store: %s", err)
	}
	if NetworkBridgeIface == "" {
	NetworkBridgeIface = DefaultNetworkBridge
	}
	netManager, err := newNetworkManager(NetworkBridgeIface)
	if err != nil {
	return nil, err
	}
	runtime := &Runtime{
	root: root,
	repository: runtimeRepo,
	containers: list.New(),
	networkManager: netManager,
	graph: g,
	repositories: repositories,
	idIndex: utils.NewTruncIndex(),
	capabilities: &Capabilities{},
	autoRestart: autoRestart,
	volumes: volumes,
	}

	if err := runtime.restore(); err != nil {
	return nil, err
	}
	return runtime, nil
	}

	// History is a convenience type for storing a list of containers,
	// ordered by creation date.
	type History []*Container

	func (history *History) Len() int {
	return len(*history)
	}

	func (history *History) Less(i, j int) bool {
	containers := *history
	return containers[j].When().Before(containers[i].When())
	}

	func (history *History) Swap(i, j int) {
	containers := *history
	tmp := containers[i]
	containers[i] = containers[j]
	containers[j] = tmp
	}

	func (history History) Add(container Container) {
	history = append(history, container)
	sort.Sort(history)
	}