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Remove statewriter interface, export more libcontainer funcs

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This temp. expands the Exec method's signature but adds a more robust
way to know when the container's process is actually released and begins
to run.  The network interfaces are not guaranteed to be up yet but this
provides a more accurate view with a single callback at this time.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
This commit is contained in:
Michael Crosby 2014-04-30 15:52:40 -07:00
parent f98f4455b9
commit 3fde553297
5 changed files with 45 additions and 52 deletions
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49
libcontainer/nsinit/exec.go
View file

@ -3,8 +3,11 @@
package nsinit
import (
"fmt"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"syscall"
"github.com/dotcloud/docker/pkg/cgroups"
@ -17,7 +20,7 @@ import (
// Exec performes setup outside of a namespace so that a container can be
// executed. Exec is a high level function for working with container namespaces.
func (ns *linuxNs) Exec(container *libcontainer.Container, term Terminal, args []string) (int, error) {
func (ns *linuxNs) Exec(container *libcontainer.Container, term Terminal, pidRoot string, args []string, startCallback func()) (int, error) {
var (
master *os.File
console string
@ -53,24 +56,24 @@ func (ns *linuxNs) Exec(container *libcontainer.Container, term Terminal, args [
if err != nil {
return -1, err
}
if err := ns.stateWriter.WritePid(command.Process.Pid, started); err != nil {
if err := WritePid(pidRoot, command.Process.Pid, started); err != nil {
command.Process.Kill()
return -1, err
}
defer ns.stateWriter.DeletePid()
defer DeletePid(pidRoot)
// Do this before syncing with child so that no children
// can escape the cgroup
activeCgroup, err := ns.SetupCgroups(container, command.Process.Pid)
cleaner, err := SetupCgroups(container, command.Process.Pid)
if err != nil {
command.Process.Kill()
return -1, err
}
if activeCgroup != nil {
defer activeCgroup.Cleanup()
if cleaner != nil {
defer cleaner.Cleanup()
}
if err := ns.InitializeNetworking(container, command.Process.Pid, syncPipe); err != nil {
if err := InitializeNetworking(container, command.Process.Pid, syncPipe); err != nil {
command.Process.Kill()
return -1, err
}
@ -78,6 +81,10 @@ func (ns *linuxNs) Exec(container *libcontainer.Container, term Terminal, args [
// Sync with child
syncPipe.Close()
if startCallback != nil {
startCallback()
}
if err := command.Wait(); err != nil {
if _, ok := err.(*exec.ExitError); !ok {
return -1, err
@ -87,7 +94,9 @@ func (ns *linuxNs) Exec(container *libcontainer.Container, term Terminal, args [
return status, err
}
func (ns *linuxNs) SetupCgroups(container *libcontainer.Container, nspid int) (cgroups.ActiveCgroup, error) {
// SetupCgroups applies the cgroup restrictions to the process running in the contaienr based
// on the container's configuration
func SetupCgroups(container *libcontainer.Container, nspid int) (cgroups.ActiveCgroup, error) {
if container.Cgroups != nil {
c := container.Cgroups
if systemd.UseSystemd() {
@ -98,7 +107,9 @@ func (ns *linuxNs) SetupCgroups(container *libcontainer.Container, nspid int) (c
return nil, nil
}
func (ns *linuxNs) InitializeNetworking(container *libcontainer.Container, nspid int, pipe *SyncPipe) error {
// InitializeNetworking creates the container's network stack outside of the namespace and moves
// interfaces into the container's net namespaces if necessary
func InitializeNetworking(container *libcontainer.Container, nspid int, pipe *SyncPipe) error {
context := libcontainer.Context{}
for _, config := range container.Networks {
strategy, err := network.GetStrategy(config.Type)
@ -111,3 +122,23 @@ func (ns *linuxNs) InitializeNetworking(container *libcontainer.Container, nspid
}
return pipe.SendToChild(context)
}
// WritePid writes the namespaced processes pid to pid and it's start time
// to the path specified
func WritePid(path string, pid int, startTime string) error {
err := ioutil.WriteFile(filepath.Join(path, "pid"), []byte(fmt.Sprint(pid)), 0655)
if err != nil {
return err
}
return ioutil.WriteFile(filepath.Join(path, "start"), []byte(startTime), 0655)
}
// DeletePid removes the pid and started file from disk when the container's process
// dies and the container is cleanly removed
func DeletePid(path string) error {
err := os.Remove(filepath.Join(path, "pid"))
if serr := os.Remove(filepath.Join(path, "start")); err == nil {
err = serr
}
return err
}