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moby--moby/daemon/execdriver/lxc/init.go
John Howard 10e2dbf375 Windows: Factor out LXC
Signed-off-by: John Howard <jhoward@microsoft.com>
2015-04-30 14:28:35 -07:00

145 lines
3.1 KiB
Go

// +build linux
package lxc
import (
"encoding/json"
"flag"
"fmt"
"log"
"os"
"os/exec"
"runtime"
"strings"
"syscall"
"github.com/docker/docker/pkg/reexec"
)
// Args provided to the init function for a driver
type InitArgs struct {
User string
Gateway string
Ip string
WorkDir string
Privileged bool
Env []string
Args []string
Mtu int
Console string
Pipe int
Root string
CapAdd string
CapDrop string
}
func init() {
// like always lxc requires a hack to get this to work
reexec.Register("/.dockerinit", dockerInititalizer)
}
func dockerInititalizer() {
initializer()
}
// initializer is the lxc driver's init function that is run inside the namespace to setup
// additional configurations
func initializer() {
runtime.LockOSThread()
args := getArgs()
if err := setupNamespace(args); err != nil {
log.Fatal(err)
}
}
func setupNamespace(args *InitArgs) error {
if err := setupEnv(args); err != nil {
return err
}
if err := finalizeNamespace(args); err != nil {
return err
}
path, err := exec.LookPath(args.Args[0])
if err != nil {
log.Printf("Unable to locate %v", args.Args[0])
os.Exit(127)
}
if err := syscall.Exec(path, args.Args, os.Environ()); err != nil {
return fmt.Errorf("dockerinit unable to execute %s - %s", path, err)
}
return nil
}
func getArgs() *InitArgs {
var (
// Get cmdline arguments
user = flag.String("u", "", "username or uid")
gateway = flag.String("g", "", "gateway address")
ip = flag.String("i", "", "ip address")
workDir = flag.String("w", "", "workdir")
privileged = flag.Bool("privileged", false, "privileged mode")
mtu = flag.Int("mtu", 1500, "interface mtu")
capAdd = flag.String("cap-add", "", "capabilities to add")
capDrop = flag.String("cap-drop", "", "capabilities to drop")
)
flag.Parse()
return &InitArgs{
User: *user,
Gateway: *gateway,
Ip: *ip,
WorkDir: *workDir,
Privileged: *privileged,
Args: flag.Args(),
Mtu: *mtu,
CapAdd: *capAdd,
CapDrop: *capDrop,
}
}
// Clear environment pollution introduced by lxc-start
func setupEnv(args *InitArgs) error {
// Get env
var env []string
dockerenv, err := os.Open(".dockerenv")
if err != nil {
return fmt.Errorf("Unable to load environment variables: %v", err)
}
defer dockerenv.Close()
if err := json.NewDecoder(dockerenv).Decode(&env); err != nil {
return fmt.Errorf("Unable to decode environment variables: %v", err)
}
// Propagate the plugin-specific container env variable
env = append(env, "container="+os.Getenv("container"))
args.Env = env
os.Clearenv()
for _, kv := range args.Env {
parts := strings.SplitN(kv, "=", 2)
if len(parts) == 1 {
parts = append(parts, "")
}
os.Setenv(parts[0], parts[1])
}
return nil
}
// Setup working directory
func setupWorkingDirectory(args *InitArgs) error {
if args.WorkDir == "" {
return nil
}
if err := syscall.Chdir(args.WorkDir); err != nil {
return fmt.Errorf("Unable to change dir to %v: %v", args.WorkDir, err)
}
return nil
}