/
driver.go
325 lines (281 loc) · 6.8 KB
/
driver.go
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package lxc
import (
"fmt"
"github.com/dotcloud/docker/execdriver"
"github.com/dotcloud/docker/utils"
"io/ioutil"
"log"
"os"
"os/exec"
"path"
"strconv"
"strings"
"syscall"
"time"
)
const DriverName = "lxc"
func init() {
execdriver.RegisterInitFunc(DriverName, func(args *execdriver.InitArgs) error {
if err := setupHostname(args); err != nil {
return err
}
if err := setupNetworking(args); err != nil {
return err
}
if err := setupCapabilities(args); err != nil {
return err
}
if err := setupWorkingDirectory(args); err != nil {
return err
}
if err := changeUser(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)
}
panic("Unreachable")
})
}
type driver struct {
root string // root path for the driver to use
apparmor bool
sharedRoot bool
}
func NewDriver(root string, apparmor bool) (*driver, error) {
// setup unconfined symlink
if err := linkLxcStart(root); err != nil {
return nil, err
}
return &driver{
apparmor: apparmor,
root: root,
sharedRoot: rootIsShared(),
}, nil
}
func (d *driver) Name() string {
version := d.version()
return fmt.Sprintf("%s-%s", DriverName, version)
}
func (d *driver) Run(c *execdriver.Command, startCallback execdriver.StartCallback) (int, error) {
configPath, err := d.generateLXCConfig(c)
if err != nil {
return -1, err
}
params := []string{
"lxc-start",
"-n", c.ID,
"-f", configPath,
"--",
c.InitPath,
"-driver",
DriverName,
}
if c.Network != nil {
params = append(params,
"-g", c.Network.Gateway,
"-i", fmt.Sprintf("%s/%d", c.Network.IPAddress, c.Network.IPPrefixLen),
"-mtu", strconv.Itoa(c.Network.Mtu),
)
}
if c.User != "" {
params = append(params, "-u", c.User)
}
if c.Privileged {
if d.apparmor {
params[0] = path.Join(d.root, "lxc-start-unconfined")
}
params = append(params, "-privileged")
}
if c.WorkingDir != "" {
params = append(params, "-w", c.WorkingDir)
}
params = append(params, "--", c.Entrypoint)
params = append(params, c.Arguments...)
if d.sharedRoot {
// lxc-start really needs / to be non-shared, or all kinds of stuff break
// when lxc-start unmount things and those unmounts propagate to the main
// mount namespace.
// What we really want is to clone into a new namespace and then
// mount / MS_REC|MS_SLAVE, but since we can't really clone or fork
// without exec in go we have to do this horrible shell hack...
shellString :=
"mount --make-rslave /; exec " +
utils.ShellQuoteArguments(params)
params = []string{
"unshare", "-m", "--", "/bin/sh", "-c", shellString,
}
}
var (
name = params[0]
arg = params[1:]
)
aname, err := exec.LookPath(name)
if err != nil {
aname = name
}
c.Path = aname
c.Args = append([]string{name}, arg...)
if err := c.Start(); err != nil {
return -1, err
}
var (
waitErr error
waitLock = make(chan struct{})
)
go func() {
if err := c.Wait(); err != nil {
waitErr = err
}
close(waitLock)
}()
// Poll lxc for RUNNING status
if err := d.waitForStart(c, waitLock); err != nil {
return -1, err
}
if startCallback != nil {
startCallback(c)
}
<-waitLock
return c.GetExitCode(), waitErr
}
func (d *driver) Kill(c *execdriver.Command, sig int) error {
return d.kill(c, sig)
}
func (d *driver) Restore(c *execdriver.Command) error {
for {
output, err := exec.Command("lxc-info", "-n", c.ID).CombinedOutput()
if err != nil {
return err
}
if !strings.Contains(string(output), "RUNNING") {
return nil
}
time.Sleep(500 * time.Millisecond)
}
}
func (d *driver) version() string {
version := ""
if output, err := exec.Command("lxc-version").CombinedOutput(); err == nil {
outputStr := string(output)
if len(strings.SplitN(outputStr, ":", 2)) == 2 {
version = strings.TrimSpace(strings.SplitN(outputStr, ":", 2)[1])
}
}
return version
}
func (d *driver) kill(c *execdriver.Command, sig int) error {
output, err := exec.Command("lxc-kill", "-n", c.ID, strconv.Itoa(sig)).CombinedOutput()
if err != nil {
return fmt.Errorf("Err: %s Output: %s", err, output)
}
return nil
}
func (d *driver) waitForStart(c *execdriver.Command, waitLock chan struct{}) error {
var (
err error
output []byte
)
// We wait for the container to be fully running.
// Timeout after 5 seconds. In case of broken pipe, just retry.
// Note: The container can run and finish correctly before
// the end of this loop
for now := time.Now(); time.Since(now) < 5*time.Second; {
select {
case <-waitLock:
// If the process dies while waiting for it, just return
return nil
if c.ProcessState != nil && c.ProcessState.Exited() {
return nil
}
default:
}
output, err = d.getInfo(c.ID)
if err != nil {
output, err = d.getInfo(c.ID)
if err != nil {
return err
}
}
if strings.Contains(string(output), "RUNNING") {
return nil
}
time.Sleep(50 * time.Millisecond)
}
return execdriver.ErrNotRunning
}
func (d *driver) getInfo(id string) ([]byte, error) {
return exec.Command("lxc-info", "-s", "-n", id).CombinedOutput()
}
type info struct {
ID string
driver *driver
}
func (i *info) IsRunning() bool {
var running bool
output, err := i.driver.getInfo(i.ID)
if err != nil {
panic(err)
}
if strings.Contains(string(output), "RUNNING") {
running = true
}
return running
}
func (d *driver) Info(id string) execdriver.Info {
return &info{
ID: id,
driver: d,
}
}
func linkLxcStart(root string) error {
sourcePath, err := exec.LookPath("lxc-start")
if err != nil {
return err
}
targetPath := path.Join(root, "lxc-start-unconfined")
if _, err := os.Lstat(targetPath); err != nil && !os.IsNotExist(err) {
return err
} else if err == nil {
if err := os.Remove(targetPath); err != nil {
return err
}
}
return os.Symlink(sourcePath, targetPath)
}
// TODO: This can be moved to the mountinfo reader in the mount pkg
func rootIsShared() bool {
if data, err := ioutil.ReadFile("/proc/self/mountinfo"); err == nil {
for _, line := range strings.Split(string(data), "\n") {
cols := strings.Split(line, " ")
if len(cols) >= 6 && cols[4] == "/" {
return strings.HasPrefix(cols[6], "shared")
}
}
}
// No idea, probably safe to assume so
return true
}
func (d *driver) generateLXCConfig(c *execdriver.Command) (string, error) {
root := path.Join(d.root, "containers", c.ID, "config.lxc")
fo, err := os.Create(root)
if err != nil {
return "", err
}
defer fo.Close()
if err := LxcTemplateCompiled.Execute(fo, struct {
*execdriver.Command
AppArmor bool
}{
Command: c,
AppArmor: d.apparmor,
}); err != nil {
return "", err
}
return root, nil
}