Merge pull request #6207 from crosbymichael/nsinit-cli

Make nsinit nicer to work with libcontainer

libcontainer/nsinit/exec.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"os/signal"
+
+	"github.com/codegangsta/cli"
+	"github.com/dotcloud/docker/pkg/libcontainer"
+	"github.com/dotcloud/docker/pkg/libcontainer/namespaces"
+)
+
+var execCommand = cli.Command{
+	Name:   "exec",
+	Usage:  "execute a new command inside a container",
+	Action: execAction,
+}
+
+func execAction(context *cli.Context) {
+	var nspid, exitCode int
+
+	container, err := loadContainer()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if nspid, err = readPid(); err != nil && !os.IsNotExist(err) {
+		log.Fatalf("unable to read pid: %s", err)
+	}
+
+	if nspid > 0 {
+		err = namespaces.ExecIn(container, nspid, []string(context.Args()))
+	} else {
+		term := namespaces.NewTerminal(os.Stdin, os.Stdout, os.Stderr, container.Tty)
+		exitCode, err = startContainer(container, term, dataPath, []string(context.Args()))
+	}
+
+	if err != nil {
+		log.Fatalf("failed to exec: %s", err)
+	}
+
+	os.Exit(exitCode)
+}
+
+// startContainer starts the container. Returns the exit status or -1 and an
+// error.
+//
+// Signals sent to the current process will be forwarded to container.
+func startContainer(container *libcontainer.Container, term namespaces.Terminal, dataPath string, args []string) (int, error) {
+	var (
+		cmd  *exec.Cmd
+		sigc = make(chan os.Signal, 10)
+	)
+
+	signal.Notify(sigc)
+
+	createCommand := func(container *libcontainer.Container, console, rootfs, dataPath, init string, pipe *os.File, args []string) *exec.Cmd {
+		cmd = namespaces.DefaultCreateCommand(container, console, rootfs, dataPath, init, pipe, args)
+		if logPath != "" {
+			cmd.Env = append(cmd.Env, fmt.Sprintf("log=%s", logPath))
+		}
+		return cmd
+	}
+
+	startCallback := func() {
+		go func() {
+			for sig := range sigc {
+				cmd.Process.Signal(sig)
+			}
+		}()
+	}
+
+	return namespaces.Exec(container, term, "", dataPath, args, createCommand, startCallback)
+}

libcontainer/nsinit/init.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"log"
+	"os"
+	"strconv"
+
+	"github.com/codegangsta/cli"
+	"github.com/dotcloud/docker/pkg/libcontainer/namespaces"
+)
+
+var (
+	dataPath  = os.Getenv("data_path")
+	console   = os.Getenv("console")
+	rawPipeFd = os.Getenv("pipe")
+
+	initCommand = cli.Command{
+		Name:   "init",
+		Usage:  "runs the init process inside the namespace",
+		Action: initAction,
+	}
+)
+
+func initAction(context *cli.Context) {
+	container, err := loadContainer()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	rootfs, err := os.Getwd()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	pipeFd, err := strconv.Atoi(rawPipeFd)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	syncPipe, err := namespaces.NewSyncPipeFromFd(0, uintptr(pipeFd))
+	if err != nil {
+		log.Fatalf("unable to create sync pipe: %s", err)
+	}
+
+	if err := namespaces.Init(container, rootfs, console, syncPipe, []string(context.Args())); err != nil {
+		log.Fatalf("unable to initialize for container: %s", err)
+	}
+}

libcontainer/nsinit/main.go

@@ -1,220 +1,40 @@
 package main
 
 import (
-	"encoding/json"
-	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
-	"os/exec"
-	"os/signal"
-	"path/filepath"
-	"strconv"
 
-	"github.com/dotcloud/docker/pkg/libcontainer"
+	"github.com/codegangsta/cli"
-	"github.com/dotcloud/docker/pkg/libcontainer/cgroups/fs"
-	"github.com/dotcloud/docker/pkg/libcontainer/namespaces"
 )
 
-var (
+var logPath = os.Getenv("log")
-	dataPath  = os.Getenv("data_path")
+
-	console   = os.Getenv("console")
+func preload(context *cli.Context) error {
-	rawPipeFd = os.Getenv("pipe")
+	if logPath != "" {
-)
+		if err := openLog(logPath); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
 
 func main() {
-	if len(os.Args) < 2 {
+	app := cli.NewApp()
-		log.Fatalf("invalid number of arguments %d", len(os.Args))
+	app.Name = "nsinit"
+	app.Version = "0.1"
+	app.Author = "libcontainer maintainers"
+
+	app.Before = preload
+	app.Commands = []cli.Command{
+		execCommand,
+		initCommand,
+		statsCommand,
+		specCommand,
+		nsenterCommand,
 	}
 
-	switch os.Args[1] {
+	if err := app.Run(os.Args); err != nil {
-	case "exec": // this is executed outside of the namespace in the cwd
+		log.Fatal(err)
-		container, err := loadContainer()
-		if err != nil {
-			log.Fatalf("unable to load container: %s", err)
-		}
-
-		var nspid, exitCode int
-		if nspid, err = readPid(); err != nil && !os.IsNotExist(err) {
-			log.Fatalf("unable to read pid: %s", err)
-		}
-
-		if nspid > 0 {
-			err = namespaces.ExecIn(container, nspid, os.Args[2:])
-		} else {
-			term := namespaces.NewTerminal(os.Stdin, os.Stdout, os.Stderr, container.Tty)
-			exitCode, err = startContainer(container, term, dataPath, os.Args[2:])
-		}
-
-		if err != nil {
-			log.Fatalf("failed to exec: %s", err)
-		}
-		os.Exit(exitCode)
-	case "nsenter": // this is executed inside the namespace.
-		// nsinit nsenter <pid> <process label> <container JSON> <cmd>...
-		if len(os.Args) < 6 {
-			log.Fatalf("incorrect usage: nsinit nsenter <pid> <process label> <container JSON> <cmd>...")
-		}
-
-		container, err := loadContainerFromJson(os.Args[4])
-		if err != nil {
-			log.Fatalf("unable to load container: %s", err)
-		}
-
-		nspid, err := strconv.Atoi(os.Args[2])
-		if err != nil {
-			log.Fatalf("unable to read pid: %s from %q", err, os.Args[2])
-		}
-
-		if nspid <= 0 {
-			log.Fatalf("cannot enter into namespaces without valid pid: %q", nspid)
-		}
-
-		err = namespaces.NsEnter(container, os.Args[3], nspid, os.Args[5:])
-		if err != nil {
-			log.Fatalf("failed to nsenter: %s", err)
-		}
-	case "init": // this is executed inside of the namespace to setup the container
-		container, err := loadContainer()
-		if err != nil {
-			log.Fatalf("unable to load container: %s", err)
-		}
-
-		// by default our current dir is always our rootfs
-		rootfs, err := os.Getwd()
-		if err != nil {
-			log.Fatal(err)
-		}
-
-		pipeFd, err := strconv.Atoi(rawPipeFd)
-		if err != nil {
-			log.Fatal(err)
-		}
-		syncPipe, err := namespaces.NewSyncPipeFromFd(0, uintptr(pipeFd))
-		if err != nil {
-			log.Fatalf("unable to create sync pipe: %s", err)
-		}
-
-		if err := namespaces.Init(container, rootfs, console, syncPipe, os.Args[2:]); err != nil {
-			log.Fatalf("unable to initialize for container: %s", err)
-		}
-	case "stats":
-		container, err := loadContainer()
-		if err != nil {
-			log.Fatalf("unable to load container: %s", err)
-		}
-
-		// returns the stats of the current container.
-		stats, err := getContainerStats(container)
-		if err != nil {
-			log.Printf("Failed to get stats - %v\n", err)
-			os.Exit(1)
-		}
-		fmt.Printf("Stats:\n%v\n", stats)
-		os.Exit(0)
-
-	case "spec":
-		container, err := loadContainer()
-		if err != nil {
-			log.Fatalf("unable to load container: %s", err)
-		}
-
-		// returns the spec of the current container.
-		spec, err := getContainerSpec(container)
-		if err != nil {
-			log.Printf("Failed to get spec - %v\n", err)
-			os.Exit(1)
-		}
-		fmt.Printf("Spec:\n%v\n", spec)
-		os.Exit(0)
-
-	default:
-		log.Fatalf("command not supported for nsinit %s", os.Args[1])
 	}
 }
-
-func loadContainer() (*libcontainer.Container, error) {
-	f, err := os.Open(filepath.Join(dataPath, "container.json"))
-	if err != nil {
-		log.Printf("Path: %q", filepath.Join(dataPath, "container.json"))
-		return nil, err
-	}
-	defer f.Close()
-
-	var container *libcontainer.Container
-	if err := json.NewDecoder(f).Decode(&container); err != nil {
-		return nil, err
-	}
-	return container, nil
-}
-
-func loadContainerFromJson(rawData string) (*libcontainer.Container, error) {
-	container := &libcontainer.Container{}
-	err := json.Unmarshal([]byte(rawData), container)
-	if err != nil {
-		return nil, err
-	}
-	return container, nil
-}
-
-func readPid() (int, error) {
-	data, err := ioutil.ReadFile(filepath.Join(dataPath, "pid"))
-	if err != nil {
-		return -1, err
-	}
-	pid, err := strconv.Atoi(string(data))
-	if err != nil {
-		return -1, err
-	}
-	return pid, nil
-}
-
-// startContainer starts the container. Returns the exit status or -1 and an
-// error.
-//
-// Signals sent to the current process will be forwarded to container.
-func startContainer(container *libcontainer.Container, term namespaces.Terminal, dataPath string, args []string) (int, error) {
-	var (
-		cmd  *exec.Cmd
-		sigc = make(chan os.Signal, 10)
-	)
-
-	signal.Notify(sigc)
-
-	createCommand := func(container *libcontainer.Container, console, rootfs, dataPath, init string, pipe *os.File, args []string) *exec.Cmd {
-		cmd = namespaces.DefaultCreateCommand(container, console, rootfs, dataPath, init, pipe, args)
-		return cmd
-	}
-
-	startCallback := func() {
-		go func() {
-			for sig := range sigc {
-				cmd.Process.Signal(sig)
-			}
-		}()
-	}
-
-	return namespaces.Exec(container, term, "", dataPath, args, createCommand, startCallback)
-}
-
-// returns the container stats in json format.
-func getContainerStats(container *libcontainer.Container) (string, error) {
-	stats, err := fs.GetStats(container.Cgroups)
-	if err != nil {
-		return "", err
-	}
-	out, err := json.MarshalIndent(stats, "", "\t")
-	if err != nil {
-		return "", err
-	}
-	return string(out), nil
-}
-
-// returns the container spec in json format.
-func getContainerSpec(container *libcontainer.Container) (string, error) {
-	spec, err := json.MarshalIndent(container, "", "\t")
-	if err != nil {
-		return "", err
-	}
-	return string(spec), nil
-}

libcontainer/nsinit/nsenter.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"log"
+	"strconv"
+
+	"github.com/codegangsta/cli"
+	"github.com/dotcloud/docker/pkg/libcontainer/namespaces"
+)
+
+var nsenterCommand = cli.Command{
+	Name:   "nsenter",
+	Usage:  "init process for entering an existing namespace",
+	Action: nsenterAction,
+}
+
+func nsenterAction(context *cli.Context) {
+	args := context.Args()
+	if len(args) < 4 {
+		log.Fatalf("incorrect usage: <pid> <process label> <container JSON> <cmd>...")
+	}
+
+	container, err := loadContainerFromJson(args.Get(2))
+	if err != nil {
+		log.Fatalf("unable to load container: %s", err)
+	}
+
+	nspid, err := strconv.Atoi(args.Get(0))
+	if err != nil {
+		log.Fatalf("unable to read pid: %s from %q", err, args.Get(0))
+	}
+
+	if nspid <= 0 {
+		log.Fatalf("cannot enter into namespaces without valid pid: %q", nspid)
+	}
+
+	if err := namespaces.NsEnter(container, args.Get(1), nspid, args[3:]); err != nil {
+		log.Fatalf("failed to nsenter: %s", err)
+	}
+}

libcontainer/nsinit/spec.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+
+	"github.com/codegangsta/cli"
+	"github.com/dotcloud/docker/pkg/libcontainer"
+)
+
+var specCommand = cli.Command{
+	Name:   "spec",
+	Usage:  "display the container specification",
+	Action: specAction,
+}
+
+func specAction(context *cli.Context) {
+	container, err := loadContainer()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	spec, err := getContainerSpec(container)
+	if err != nil {
+		log.Fatalf("Failed to get spec - %v\n", err)
+	}
+
+	fmt.Printf("Spec:\n%v\n", spec)
+}
+
+// returns the container spec in json format.
+func getContainerSpec(container *libcontainer.Container) (string, error) {
+	spec, err := json.MarshalIndent(container, "", "\t")
+	if err != nil {
+		return "", err
+	}
+
+	return string(spec), nil
+}

libcontainer/nsinit/stats.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+
+	"github.com/codegangsta/cli"
+	"github.com/dotcloud/docker/pkg/libcontainer"
+	"github.com/dotcloud/docker/pkg/libcontainer/cgroups/fs"
+)
+
+var statsCommand = cli.Command{
+	Name:   "stats",
+	Usage:  "display statistics for the container",
+	Action: statsAction,
+}
+
+func statsAction(context *cli.Context) {
+	container, err := loadContainer()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	stats, err := getContainerStats(container)
+	if err != nil {
+		log.Fatalf("Failed to get stats - %v\n", err)
+	}
+
+	fmt.Printf("Stats:\n%v\n", stats)
+}
+
+// returns the container stats in json format.
+func getContainerStats(container *libcontainer.Container) (string, error) {
+	stats, err := fs.GetStats(container.Cgroups)
+	if err != nil {
+		return "", err
+	}
+
+	out, err := json.MarshalIndent(stats, "", "\t")
+	if err != nil {
+		return "", err
+	}
+
+	return string(out), nil
+}

libcontainer/nsinit/utils.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strconv"
+
+	"github.com/dotcloud/docker/pkg/libcontainer"
+)
+
+func loadContainer() (*libcontainer.Container, error) {
+	f, err := os.Open(filepath.Join(dataPath, "container.json"))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var container *libcontainer.Container
+	if err := json.NewDecoder(f).Decode(&container); err != nil {
+		return nil, err
+	}
+
+	return container, nil
+}
+
+func readPid() (int, error) {
+	data, err := ioutil.ReadFile(filepath.Join(dataPath, "pid"))
+	if err != nil {
+		return -1, err
+	}
+
+	pid, err := strconv.Atoi(string(data))
+	if err != nil {
+		return -1, err
+	}
+
+	return pid, nil
+}
+
+func openLog(name string) error {
+	f, err := os.OpenFile(name, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0755)
+	if err != nil {
+		return err
+	}
+
+	log.SetOutput(f)
+
+	return nil
+}
+
+func loadContainerFromJson(rawData string) (*libcontainer.Container, error) {
+	var container *libcontainer.Container
+
+	if err := json.Unmarshal([]byte(rawData), &container); err != nil {
+		return nil, err
+	}
+
+	return container, nil
+}