exec.Command("/proc/self/exe", "child")

package main

import (
        "flag"
        "os"
        "os/exec"
        "syscall"

        "github.com/sirupsen/logrus"
)

func main() {
        var nsShell, nsHostName, rootPath string
        flag.StringVar(&nsShell, "nsshell", "/bin/bash", "The path to the shell where the namespace is running")
        flag.StringVar(&nsHostName, "nshostname", "nshost", "Path to the shell to use")
        //~/docker/container/rootfs会报错
        flag.StringVar(&rootPath, "rootfs", "/root/docker/container/rootfs/", "Path to the root filesystem to use")
        flag.Parse()
        switch os.Args[1] {
        case "run":
                nsRun(nsShell, nsHostName, rootPath)
        case "child":
                chRoot(nsShell, rootPath)
        default:
                logrus.Errorf("wrong command")
                return
        }

}

//nsInit ns初始化
func nsInit(command, hostname, newRootPath string) {
        //check(mountRoot(newRootPath))
        nsRun(command, hostname, newRootPath)
}

func nsRun(command, hostname, newRootPath string) {
        cmd := exec.Command("/proc/self/exe", "child")
        cmd.Stdin = os.Stdin
        cmd.Stdout = os.Stdout
        cmd.Stderr = os.Stderr
        cmd.SysProcAttr = &syscall.SysProcAttr{
                Cloneflags: syscall.CLONE_NEWUTS | syscall.CLONE_NEWPID,
        }
        check(syscall.Sethostname([]byte(hostname)))
        check(cmd.Run())
}

func chRoot(command, newroot string) {
        cmd := exec.Command(command)
        cmd.Stdin = os.Stdin
        cmd.Stdout = os.Stdout
        cmd.Stderr = os.Stderr
        check(syscall.Chroot(newroot))
        check(os.Chdir("/"))
        check(syscall.Mount("proc", "proc", "proc", 0, ""))
        check(cmd.Run())
        check(syscall.Unmount("proc", 0))
}

func check(err error) {
        if err != nil {
                logrus.Errorln(err)
        }
}

root@ubuntu:/home/ubuntu/test/learning/namespaces/PID_001# go run PID_001.go run
root@nshost:/# ps -a
PID   USER     TIME  COMMAND
    1 root      0:00 /proc/self/exe child
    6 root      0:00 /bin/bash
    7 root      0:00 ps -a
root@nshost:/# hostname
nshost
root@nshost:/#

network没有隔离

host上