main.go

package main

import (
	"context"
	"fmt"
	"net"
	"os"
	"os/signal"
	"runtime"
	"time"

	gocontext "golang.org/x/net/context"

	"github.com/Sirupsen/logrus"
	"github.com/containerd/containerd/log"
	"github.com/containerd/containerd/server"
	"github.com/containerd/containerd/sys"
	"github.com/containerd/containerd/version"
	"github.com/pkg/errors"
	"github.com/urfave/cli"
)

const usage = `
                    __        _                     __
  _________  ____  / /_____ _(_)___  ___  _________/ /
 / ___/ __ \/ __ \/ __/ __ ` + "`" + `/ / __ \/ _ \/ ___/ __  /
/ /__/ /_/ / / / / /_/ /_/ / / / / /  __/ /  / /_/ /
\___/\____/_/ /_/\__/\__,_/_/_/ /_/\___/_/   \__,_/

high performance container runtime
`

func init() {
	cli.VersionPrinter = func(c *cli.Context) {
		fmt.Println(c.App.Name, version.Package, c.App.Version)
	}
}

func main() {
	app := cli.NewApp()
	app.Name = "containerd"
	app.Version = version.Version
	app.Usage = usage
	app.Flags = []cli.Flag{
		cli.StringFlag{
			Name:  "config,c",
			Usage: "path to the configuration file",
			Value: defaultConfigPath,
		},
		cli.StringFlag{
			Name:  "log-level,l",
			Usage: "set the logging level [debug, info, warn, error, fatal, panic]",
		},
		cli.StringFlag{
			Name:  "address,a",
			Usage: "address for containerd's GRPC server",
		},
		cli.StringFlag{
			Name:  "root",
			Usage: "containerd root directory",
		},
	}
	app.Commands = []cli.Command{
		configCommand,
	}
	app.Action = func(context *cli.Context) error {
		var (
			start   = time.Now()
			signals = make(chan os.Signal, 2048)
			ctx     = log.WithModule(gocontext.Background(), "containerd")
			config  = defaultConfig()
		)
		// start the signal handler as soon as we can to make sure that
		// we don't miss any signals during boot
		signal.Notify(signals, handledSignals...)

		if err := server.LoadConfig(context.GlobalString("config"), config); err != nil && !os.IsNotExist(err) {
			return err
		}
		// apply flags to the config
		if err := applyFlags(context, config); err != nil {
			return err
		}
		address := config.GRPC.Address
		if address == "" {
			return errors.New("grpc address cannot be empty")
		}
		log.G(ctx).Info("starting containerd boot...")

		server, err := server.New(ctx, config)
		if err != nil {
			return err
		}
		if config.Debug.Address != "" {
			l, err := sys.GetLocalListener(config.Debug.Address, config.Debug.Uid, config.Debug.Gid)
			if err != nil {
				return errors.Wrapf(err, "failed to get listener for debug endpoint")
			}
			serve(log.WithModule(ctx, "debug"), l, server.ServeDebug)
		}
		if config.Metrics.Address != "" {
			l, err := net.Listen("tcp", config.Metrics.Address)
			if err != nil {
				return errors.Wrapf(err, "failed to get listener for metrics endpoint")
			}
			serve(log.WithModule(ctx, "metrics"), l, server.ServeMetrics)
		}

		l, err := sys.GetLocalListener(address, config.GRPC.Uid, config.GRPC.Gid)
		if err != nil {
			return errors.Wrapf(err, "failed to get listener for main endpoint")
		}
		serve(log.WithModule(ctx, "grpc"), l, server.ServeGRPC)

		log.G(ctx).Infof("containerd successfully booted in %fs", time.Since(start).Seconds())
		return handleSignals(ctx, signals, server)
	}
	if err := app.Run(os.Args); err != nil {
		fmt.Fprintf(os.Stderr, "containerd: %s\n", err)
		os.Exit(1)
	}
}

func serve(ctx context.Context, l net.Listener, serveFunc func(net.Listener) error) {
	path := l.Addr().String()
	log.G(ctx).WithField("address", path).Info("serving...")
	go func() {
		defer l.Close()
		if err := serveFunc(l); err != nil {
			log.G(ctx).WithError(err).WithField("address", path).Fatal("serve failure")
		}
	}()
}

func applyFlags(context *cli.Context, config *server.Config) error {
	// the order for config vs flag values is that flags will always override
	// the config values if they are set
	if err := setLevel(context, config); err != nil {
		return err
	}
	for _, v := range []struct {
		name string
		d    *string
	}{
		{
			name: "root",
			d:    &config.Root,
		},
		{
			name: "address",
			d:    &config.GRPC.Address,
		},
	} {
		if s := context.GlobalString(v.name); s != "" {
			*v.d = s
		}
	}
	return nil
}

func setLevel(context *cli.Context, config *server.Config) error {
	l := context.GlobalString("log-level")
	if l == "" {
		l = config.Debug.Level
	}
	if l != "" {
		lvl, err := logrus.ParseLevel(l)
		if err != nil {
			return err
		}
		logrus.SetLevel(lvl)
	}
	return nil
}

func dumpStacks() {
	var (
		buf       []byte
		stackSize int
	)
	bufferLen := 16384
	for stackSize == len(buf) {
		buf = make([]byte, bufferLen)
		stackSize = runtime.Stack(buf, true)
		bufferLen *= 2
	}
	buf = buf[:stackSize]
	logrus.Infof("=== BEGIN goroutine stack dump ===\n%s\n=== END goroutine stack dump ===", buf)
}