runc/init.go

package main

import (
	"os"
	"runtime"
	"strconv"

	"github.com/opencontainers/runc/libcontainer"
	_ "github.com/opencontainers/runc/libcontainer/nsenter"
	"github.com/sirupsen/logrus"
	"github.com/urfave/cli"
)

func init() {
	if len(os.Args) > 1 && os.Args[1] == "init" {
		runtime.GOMAXPROCS(1)
		runtime.LockOSThread()

		// in child process, we need to retrieve the log pipe
		envLogPipe := os.Getenv("_LIBCONTAINER_LOGPIPE")
		logPipeFd, err := strconv.Atoi(envLogPipe)

		if err != nil {
			return
		}
		logPipe := os.NewFile(uintptr(logPipeFd), "logpipe")
		logrus.SetOutput(logPipe)
		logrus.SetFormatter(&logrus.JSONFormatter{})
		logrus.SetLevel(logrus.DebugLevel)
		logrus.Debug("child process in init()")
	}
}

var initCommand = cli.Command{
	Name:  "init",
	Usage: `initialize the namespaces and launch the process (do not call it outside of runc)`,
	Action: func(context *cli.Context) error {
		factory, _ := libcontainer.New("")
		if err := factory.StartInitialization(); err != nil {
			// as the error is sent back to the parent there is no need to log
			// or write it to stderr because the parent process will handle this
			os.Exit(1)
		}
		panic("libcontainer: container init failed to exec")
	},
}