Merge pull request openshift#79 from rjnagal/cgroup_testing

Add a standalone test utility for cgroup package.

cgroups/cgutil/cgutil.go

@@ -0,0 +1,264 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"os"
+	"syscall"
+	"time"
+
+	"github.com/codegangsta/cli"
+	"github.com/docker/libcontainer/cgroups"
+	"github.com/docker/libcontainer/cgroups/fs"
+	"github.com/docker/libcontainer/cgroups/systemd"
+)
+
+var createCommand = cli.Command{
+	Name:  "create",
+	Usage: "Create a cgroup container using the supplied configuration and initial process.",
+	Flags: []cli.Flag{
+		cli.StringFlag{"config, c", "cgroup.json", "path to container configuration (cgroups.Cgroup object)"},
+		cli.IntFlag{"pid, p", 0, "pid of the initial process in the container"},
+	},
+	Action: createAction,
+}
+
+var destroyCommand = cli.Command{
+	Name:  "destroy",
+	Usage: "Destroy an existing cgroup container.",
+	Flags: []cli.Flag{
+		cli.StringFlag{"name, n", "", "container name"},
+		cli.StringFlag{"parent, p", "", "container parent"},
+	},
+	Action: destroyAction,
+}
+
+var statsCommand = cli.Command{
+	Name:  "stats",
+	Usage: "Get stats for cgroup",
+	Flags: []cli.Flag{
+		cli.StringFlag{"name, n", "", "container name"},
+		cli.StringFlag{"parent, p", "", "container parent"},
+	},
+	Action: statsAction,
+}
+
+var pauseCommand = cli.Command{
+	Name:  "pause",
+	Usage: "Pause cgroup",
+	Flags: []cli.Flag{
+		cli.StringFlag{"name, n", "", "container name"},
+		cli.StringFlag{"parent, p", "", "container parent"},
+	},
+	Action: pauseAction,
+}
+
+var resumeCommand = cli.Command{
+	Name:  "resume",
+	Usage: "Resume a paused cgroup",
+	Flags: []cli.Flag{
+		cli.StringFlag{"name, n", "", "container name"},
+		cli.StringFlag{"parent, p", "", "container parent"},
+	},
+	Action: resumeAction,
+}
+
+var psCommand = cli.Command{
+	Name:  "ps",
+	Usage: "Get list of pids for a cgroup",
+	Flags: []cli.Flag{
+		cli.StringFlag{"name, n", "", "container name"},
+		cli.StringFlag{"parent, p", "", "container parent"},
+	},
+	Action: psAction,
+}
+
+func getConfigFromFile(c *cli.Context) (*cgroups.Cgroup, error) {
+	f, err := os.Open(c.String("config"))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var config *cgroups.Cgroup
+	if err := json.NewDecoder(f).Decode(&config); err != nil {
+		log.Fatal(err)
+	}
+	return config, 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 getConfig(context *cli.Context) (*cgroups.Cgroup, error) {
+	name := context.String("name")
+	if name == "" {
+		log.Fatal(fmt.Errorf("Missing container name"))
+	}
+	parent := context.String("parent")
+	return &cgroups.Cgroup{
+		Name:   name,
+		Parent: parent,
+	}, nil
+}
+
+func killAll(config *cgroups.Cgroup) {
+	// We could use freezer here to prevent process spawning while we are trying
+	// to kill everything. But going with more portable solution of retrying for
+	// now.
+	pids := getPids(config)
+	retry := 10
+	for len(pids) != 0 || retry > 0 {
+		killPids(pids)
+		time.Sleep(100 * time.Millisecond)
+		retry--
+		pids = getPids(config)
+	}
+	if len(pids) != 0 {
+		log.Fatal(fmt.Errorf("Could not kill existing processes in the container."))
+	}
+}
+
+func getPids(config *cgroups.Cgroup) []int {
+	pids, err := fs.GetPids(config)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return pids
+}
+
+func killPids(pids []int) {
+	for _, pid := range pids {
+		// pids might go away on their own. Ignore errors.
+		syscall.Kill(pid, syscall.SIGKILL)
+	}
+}
+
+func setFreezerState(context *cli.Context, state cgroups.FreezerState) {
+	config, err := getConfig(context)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if systemd.UseSystemd() {
+		err = systemd.Freeze(config, state)
+	} else {
+		err = fs.Freeze(config, state)
+	}
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func createAction(context *cli.Context) {
+	config, err := getConfigFromFile(context)
+	if err != nil {
+		log.Fatal(err)
+	}
+	pid := context.Int("pid")
+	if pid <= 0 {
+		log.Fatal(fmt.Errorf("Invalid pid : %d", pid))
+	}
+	if systemd.UseSystemd() {
+		_, err := systemd.Apply(config, pid)
+		if err != nil {
+			log.Fatal(err)
+		}
+	} else {
+		_, err := fs.Apply(config, pid)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}
+
+func destroyAction(context *cli.Context) {
+	config, err := getConfig(context)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	killAll(config)
+	// Systemd will clean up cgroup state for empty container.
+	if !systemd.UseSystemd() {
+		err := fs.Cleanup(config)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+}
+
+func statsAction(context *cli.Context) {
+	config, err := getConfig(context)
+	if err != nil {
+		log.Fatal(err)
+	}
+	stats, err := fs.GetStats(config)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	out, err := json.MarshalIndent(stats, "", "\t")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Usage stats for '%s':\n %v\n", config.Name, string(out))
+}
+
+func pauseAction(context *cli.Context) {
+	setFreezerState(context, cgroups.Frozen)
+}
+
+func resumeAction(context *cli.Context) {
+	setFreezerState(context, cgroups.Thawed)
+}
+
+func psAction(context *cli.Context) {
+	config, err := getConfig(context)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	pids, err := fs.GetPids(config)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Pids in '%s':\n", config.Name)
+	fmt.Println(pids)
+}
+
+func main() {
+	logPath := os.Getenv("log")
+	if logPath != "" {
+		if err := openLog(logPath); err != nil {
+			log.Fatal(err)
+		}
+	}
+
+	app := cli.NewApp()
+	app.Name = "cgutil"
+	app.Usage = "Test utility for libcontainer cgroups package"
+	app.Version = "0.1"
+
+	app.Commands = []cli.Command{
+		createCommand,
+		destroyCommand,
+		statsCommand,
+		pauseCommand,
+		resumeCommand,
+		psCommand,
+	}
+
+	if err := app.Run(os.Args); err != nil {
+		log.Fatal(err)
+	}
+}

cgroups/cgutil/sample_cgroup.json

@@ -0,0 +1,10 @@
+{
+	"name": "luke",
+	"parent": "darth",
+	"allow_all_devices": true,
+	"memory": 1073741824,
+	"memory_swap": -1,
+	"cpu_shares": 2048,
+	"cpu_quota": 500000,
+	"cpu_period": 250000
+}