Update nsinit to be nicer to work with and test
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
This commit is contained in:
Michael Crosby
parent
2b0cb56eb9
commit
4e51c8b41f
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@ -0,0 +1,74 @@
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package main
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import (
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"fmt"
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"log"
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"os"
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"os/exec"
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"os/signal"
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"github.com/codegangsta/cli"
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"github.com/dotcloud/docker/pkg/libcontainer"
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"github.com/dotcloud/docker/pkg/libcontainer/namespaces"
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)
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var execCommand = cli.Command{
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Name: "exec",
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Usage: "execute a new command inside a container",
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Action: execAction,
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}
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func execAction(context *cli.Context) {
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var (
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err error
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nspid, exitCode int
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)
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if nspid, err = readPid(); err != nil && !os.IsNotExist(err) {
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log.Fatalf("unable to read pid: %s", err)
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}
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if nspid > 0 {
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exitCode, err = namespaces.ExecIn(container, nspid, []string(context.Args()))
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} else {
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term := namespaces.NewTerminal(os.Stdin, os.Stdout, os.Stderr, container.Tty)
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exitCode, err = startContainer(container, term, dataPath, []string(context.Args()))
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}
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if err != nil {
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log.Fatalf("failed to exec: %s", err)
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}
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os.Exit(exitCode)
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}
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// startContainer starts the container. Returns the exit status or -1 and an
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// error.
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//
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// Signals sent to the current process will be forwarded to container.
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func startContainer(container *libcontainer.Container, term namespaces.Terminal, dataPath string, args []string) (int, error) {
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var (
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cmd *exec.Cmd
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sigc = make(chan os.Signal, 10)
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)
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signal.Notify(sigc)
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createCommand := func(container *libcontainer.Container, console, rootfs, dataPath, init string, pipe *os.File, args []string) *exec.Cmd {
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cmd = namespaces.DefaultCreateCommand(container, console, rootfs, dataPath, init, pipe, args)
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if logPath != "" {
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cmd.Env = append(cmd.Env, fmt.Sprintf("log=%s", logPath))
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}
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return cmd
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}
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startCallback := func() {
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go func() {
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for sig := range sigc {
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cmd.Process.Signal(sig)
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}
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}()
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}
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return namespaces.Exec(container, term, "", dataPath, args, createCommand, startCallback)
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}
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@ -0,0 +1,43 @@
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package main
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import (
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"log"
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"os"
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"strconv"
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"github.com/codegangsta/cli"
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"github.com/dotcloud/docker/pkg/libcontainer/namespaces"
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)
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var (
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dataPath = os.Getenv("data_path")
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console = os.Getenv("console")
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rawPipeFd = os.Getenv("pipe")
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initCommand = cli.Command{
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Name: "init",
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Usage: "runs the init process inside the namespace",
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Action: initAction,
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}
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)
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func initAction(context *cli.Context) {
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rootfs, err := os.Getwd()
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if err != nil {
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log.Fatal(err)
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}
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pipeFd, err := strconv.Atoi(rawPipeFd)
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if err != nil {
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log.Fatal(err)
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}
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syncPipe, err := namespaces.NewSyncPipeFromFd(0, uintptr(pipeFd))
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if err != nil {
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log.Fatalf("unable to create sync pipe: %s", err)
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}
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if err := namespaces.Init(container, rootfs, console, syncPipe, []string(context.Args())); err != nil {
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log.Fatalf("unable to initialize for container: %s", err)
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}
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}
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231
nsinit/main.go
231
nsinit/main.go
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@ -1,220 +1,45 @@
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package main
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"os/signal"
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"path/filepath"
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"strconv"
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"github.com/codegangsta/cli"
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"github.com/dotcloud/docker/pkg/libcontainer"
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"github.com/dotcloud/docker/pkg/libcontainer/cgroups/fs"
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"github.com/dotcloud/docker/pkg/libcontainer/namespaces"
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)
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var (
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dataPath = os.Getenv("data_path")
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console = os.Getenv("console")
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rawPipeFd = os.Getenv("pipe")
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container *libcontainer.Container
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logPath = os.Getenv("log")
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)
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func preload(context *cli.Context) (err error) {
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container, err = loadContainer()
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if err != nil {
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return err
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}
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if logPath != "" {
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}
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return nil
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}
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func main() {
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if len(os.Args) < 2 {
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log.Fatalf("invalid number of arguments %d", len(os.Args))
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app := cli.NewApp()
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app.Name = "nsinit"
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app.Version = "0.1"
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app.Author = "libcontainer maintainers"
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app.Before = preload
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app.Commands = []cli.Command{
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execCommand,
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initCommand,
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statsCommand,
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specCommand,
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}
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switch os.Args[1] {
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case "exec": // this is executed outside of the namespace in the cwd
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container, err := loadContainer()
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if err != nil {
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log.Fatalf("unable to load container: %s", err)
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}
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var nspid, exitCode int
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if nspid, err = readPid(); err != nil && !os.IsNotExist(err) {
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log.Fatalf("unable to read pid: %s", err)
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}
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if nspid > 0 {
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err = namespaces.ExecIn(container, nspid, os.Args[2:])
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} else {
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term := namespaces.NewTerminal(os.Stdin, os.Stdout, os.Stderr, container.Tty)
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exitCode, err = startContainer(container, term, dataPath, os.Args[2:])
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}
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if err != nil {
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log.Fatalf("failed to exec: %s", err)
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}
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os.Exit(exitCode)
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case "nsenter": // this is executed inside the namespace.
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// nsinit nsenter <pid> <process label> <container JSON> <cmd>...
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if len(os.Args) < 6 {
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log.Fatalf("incorrect usage: nsinit nsenter <pid> <process label> <container JSON> <cmd>...")
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}
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container, err := loadContainerFromJson(os.Args[4])
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if err != nil {
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log.Fatalf("unable to load container: %s", err)
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}
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nspid, err := strconv.Atoi(os.Args[2])
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if err != nil {
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log.Fatalf("unable to read pid: %s from %q", err, os.Args[2])
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}
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if nspid <= 0 {
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log.Fatalf("cannot enter into namespaces without valid pid: %q", nspid)
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}
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err = namespaces.NsEnter(container, os.Args[3], nspid, os.Args[5:])
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if err != nil {
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log.Fatalf("failed to nsenter: %s", err)
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}
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case "init": // this is executed inside of the namespace to setup the container
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container, err := loadContainer()
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if err != nil {
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log.Fatalf("unable to load container: %s", err)
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}
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// by default our current dir is always our rootfs
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rootfs, err := os.Getwd()
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if err != nil {
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log.Fatal(err)
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}
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pipeFd, err := strconv.Atoi(rawPipeFd)
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if err != nil {
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log.Fatal(err)
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}
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syncPipe, err := namespaces.NewSyncPipeFromFd(0, uintptr(pipeFd))
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if err != nil {
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log.Fatalf("unable to create sync pipe: %s", err)
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}
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if err := namespaces.Init(container, rootfs, console, syncPipe, os.Args[2:]); err != nil {
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log.Fatalf("unable to initialize for container: %s", err)
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}
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case "stats":
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container, err := loadContainer()
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if err != nil {
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log.Fatalf("unable to load container: %s", err)
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}
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// returns the stats of the current container.
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stats, err := getContainerStats(container)
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if err != nil {
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log.Printf("Failed to get stats - %v\n", err)
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os.Exit(1)
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}
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fmt.Printf("Stats:\n%v\n", stats)
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os.Exit(0)
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case "spec":
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container, err := loadContainer()
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if err != nil {
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log.Fatalf("unable to load container: %s", err)
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}
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// returns the spec of the current container.
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spec, err := getContainerSpec(container)
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if err != nil {
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log.Printf("Failed to get spec - %v\n", err)
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os.Exit(1)
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}
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fmt.Printf("Spec:\n%v\n", spec)
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os.Exit(0)
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default:
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log.Fatalf("command not supported for nsinit %s", os.Args[1])
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if err := app.Run(os.Args); err != nil {
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log.Fatal(err)
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}
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}
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func loadContainer() (*libcontainer.Container, error) {
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f, err := os.Open(filepath.Join(dataPath, "container.json"))
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if err != nil {
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log.Printf("Path: %q", filepath.Join(dataPath, "container.json"))
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return nil, err
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}
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defer f.Close()
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var container *libcontainer.Container
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if err := json.NewDecoder(f).Decode(&container); err != nil {
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return nil, err
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}
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return container, nil
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}
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func loadContainerFromJson(rawData string) (*libcontainer.Container, error) {
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container := &libcontainer.Container{}
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err := json.Unmarshal([]byte(rawData), container)
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if err != nil {
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return nil, err
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}
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return container, nil
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}
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func readPid() (int, error) {
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data, err := ioutil.ReadFile(filepath.Join(dataPath, "pid"))
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if err != nil {
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return -1, err
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}
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pid, err := strconv.Atoi(string(data))
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if err != nil {
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return -1, err
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}
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return pid, nil
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}
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// startContainer starts the container. Returns the exit status or -1 and an
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// error.
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//
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// Signals sent to the current process will be forwarded to container.
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func startContainer(container *libcontainer.Container, term namespaces.Terminal, dataPath string, args []string) (int, error) {
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var (
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cmd *exec.Cmd
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sigc = make(chan os.Signal, 10)
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)
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signal.Notify(sigc)
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createCommand := func(container *libcontainer.Container, console, rootfs, dataPath, init string, pipe *os.File, args []string) *exec.Cmd {
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cmd = namespaces.DefaultCreateCommand(container, console, rootfs, dataPath, init, pipe, args)
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return cmd
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}
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startCallback := func() {
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go func() {
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for sig := range sigc {
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cmd.Process.Signal(sig)
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}
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}()
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}
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return namespaces.Exec(container, term, "", dataPath, args, createCommand, startCallback)
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}
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// returns the container stats in json format.
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func getContainerStats(container *libcontainer.Container) (string, error) {
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stats, err := fs.GetStats(container.Cgroups)
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if err != nil {
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return "", err
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}
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out, err := json.MarshalIndent(stats, "", "\t")
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if err != nil {
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return "", err
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}
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return string(out), nil
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}
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// returns the container spec in json format.
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func getContainerSpec(container *libcontainer.Container) (string, error) {
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spec, err := json.MarshalIndent(container, "", "\t")
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if err != nil {
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return "", err
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}
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return string(spec), nil
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}
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@ -0,0 +1,38 @@
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package main
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import (
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"encoding/json"
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"fmt"
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"log"
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"os"
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"github.com/codegangsta/cli"
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"github.com/dotcloud/docker/pkg/libcontainer"
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)
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var specCommand = cli.Command{
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Name: "spec",
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Usage: "display the container specification",
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Action: specAction,
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}
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func specAction(context *cli.Context) {
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// returns the spec of the current container.
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spec, err := getContainerSpec(container)
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if err != nil {
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log.Printf("Failed to get spec - %v\n", err)
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os.Exit(1)
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}
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fmt.Printf("Spec:\n%v\n", spec)
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os.Exit(0)
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}
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// returns the container spec in json format.
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func getContainerSpec(container *libcontainer.Container) (string, error) {
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spec, err := json.MarshalIndent(container, "", "\t")
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if err != nil {
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return "", err
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}
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return string(spec), nil
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}
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@ -0,0 +1,42 @@
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package main
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import (
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"encoding/json"
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"fmt"
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"log"
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"os"
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"github.com/codegangsta/cli"
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"github.com/dotcloud/docker/pkg/libcontainer"
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"github.com/dotcloud/docker/pkg/libcontainer/cgroups/fs"
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)
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var statsCommand = cli.Command{
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Name: "stats",
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Usage: "display statistics for the container",
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Action: statsAction,
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}
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func statsAction(context *cli.Context) {
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// returns the stats of the current container.
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stats, err := getContainerStats(container)
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if err != nil {
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log.Printf("Failed to get stats - %v\n", err)
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os.Exit(1)
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}
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fmt.Printf("Stats:\n%v\n", stats)
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os.Exit(0)
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}
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// returns the container stats in json format.
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func getContainerStats(container *libcontainer.Container) (string, error) {
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stats, err := fs.GetStats(container.Cgroups)
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if err != nil {
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return "", err
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}
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out, err := json.MarshalIndent(stats, "", "\t")
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if err != nil {
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return "", err
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}
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return string(out), nil
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}
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@ -0,0 +1,52 @@
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package main
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import (
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"encoding/json"
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"io/ioutil"
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"log"
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"os"
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"path/filepath"
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"strconv"
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"github.com/dotcloud/docker/pkg/libcontainer"
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)
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func loadContainer() (*libcontainer.Container, error) {
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f, err := os.Open(filepath.Join(dataPath, "container.json"))
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if err != nil {
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return nil, err
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}
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defer f.Close()
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var container *libcontainer.Container
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if err := json.NewDecoder(f).Decode(&container); err != nil {
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return nil, err
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}
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return container, nil
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}
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func readPid() (int, error) {
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data, err := ioutil.ReadFile(filepath.Join(dataPath, "pid"))
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if err != nil {
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return -1, err
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}
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pid, err := strconv.Atoi(string(data))
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if err != nil {
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return -1, err
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}
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return pid, nil
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}
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func openLog(name string) error {
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f, err := os.OpenFile(name, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0755)
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if err != nil {
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return err
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}
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log.SetOutput(f)
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return nil
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}
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